North America
North America
Geologic history North America in the Archean eon
North America in the Proterozoic eon
Eastern and southern borders of North America
Western border of North America
Modern geologic events in North America
The landmass occupied by the present–day countries of Canada, the United States, and the Republic of Mexico make up North America. Greenland (Kalaallit Nunaat), an island landmass to the northeast of Canada, is also included in North America, for it has been attached to Canada for almost two billion years.
Plate tectonics is the main force of nature responsible for the geologic history of North America. Over ages of geologic time, the plates have come together to form the continents, including North America. Other processes, such as sedimentation and erosion, modify the shape of the land that has been forged by platetectonics.
North American geologic history includes several types of mountain ranges as a result of plate tectonics. When the edge of a plate of earth’s crust runs over another plate, forcing the lower plate deep into Earth’s elastic interior, a long, curved mountain chain of volcanos usually forms on the forward–moving edge of the upper plate. When this border between two plates forms in the middle of the ocean, the volcanic mountains form a string of islands, or archipelago, such as the Antilles and the Aleutians. This phenomenon is called an island arc.
When the upper plate is carrying a continent on its forward edge, a mountain chain, like the Cascades, forms right on the forward edge. This edge, heavily populated with volcanos, is called a continental arc. The volcanic mountains on the plate border described above can run into a continent, shatter the collision area and stack up the pieces into a mountain range. This is how the Appalachians were formed. Imagine how high your school would reach if it were squeezed by bulldozers so it remained the same length east to west as it is now, but from north to south measured the width of a convenience store restroom. The result would be a tall wall of fractured rubble, and that is just what a collisional mountain belt is.
When a continent–sized “layer cake” of rock is pushed, the upper layers move more readily than the lower layers. The layers separate from each other, and the upper few miles of rock move on ahead, floating on fluid pressure between the upper and lower sections of the crust like a fully loaded tractor trailer gliding effortlessly along an icy road. The flat surface where moving layers of crust slide along the top of the layers beneath it is called a thrust fault, and the mountains that are heaved up where the thrust fault reaches the surface are one kind of fault block mountains. The mountains of Glacier National Park slid along the Lewis thrust fault over younger rocks, and out onto the Great Plains.
Another kind of fault block mountains comes from stretching of Earth’s crust. A model of this kind of mountains could be made by compacting a 6–in (15–cm) thick layer of moist sand on top of a rubber (not rubberized) sheet. When the sheet stretches, mimicking the elastic properties of the lower crust, the sand will crack along lines perpendicular to the direction the sheet is being pulled. Some of the surface will remain the same height, and some blocks will slide down the sides of the blocks which remain stable. This is particularly noticeable if the top surface of the compacted sand has been dusted with powder. This is a model of the process that formed the mountains in the Basin and Range province.
Mountain ranges start being torn down by physical and chemical forces while they are still rising. North America has been criss–crossed by one immense range of mountains after another throughout its almost four–billion–year history.
A range of mountains may persist for hundreds of millions of years, like the Appalachians. On repeated occasions, the warped, folded rocks of the Appalachians were brought up out of the continent’s basement and raised thousands of feet by tectonic forces. If mountains are not continuously uplifted, they are worn down by erosion in a few million years. In North America’s geologic past, eroded particles from its mountains were carried by streams and dumped into the continent’s inland seas, some of which were as large as the present–day Mediterranean. Those rivers and seas are gone from the continent, but the sediments that filled them remain, like dirt in a bathtub when the water is drained. The roots of all the mountain ranges that have ever stood in North America all still exist, and much of the sand and clay into which the mountains were transformed still exists also, as rock or soil formations.
Geologic history North America in the Archean eon
North America was not formed in one piece, or at one time, the way a cake is baked from batter. Various parts of it were formed all over the world, at various times over four billion years, and were brought together and assembled into one continent by the endless process of plate tectonics. What is now called North America began to form in the first two and one–half billion years of Earth’s history, a period of time called the Archean eon.
Some geologists speculate that the earth that created the oldest parts of North America barely resembled the middle–aged planet on which we live. The planet of four billion years ago had cooled enough to have a solid crust, and oceans of liquid water. But the crust may have included hundreds of small tectonic plates, moving perhaps ten times faster than plates move today. These small plates, carrying what are now the most ancient rocks, scudded across the oceans of a frantic crazy–quilt planet. Active volcanos and rifts played a role in rock formation on the Archean Earth. The oldest regions in North America were formed in this hyperactive world. These regions are in Greenland, Labrador, Minnesota, and Wyoming.
Earth changed over the next billion years. A sudden surge of continental construction created much of North America. Between three and four billion years ago, great basalt plateaus gradually built up under the oceans. As the planet cooled, the rock on the undersides of these plateaus changed from basalt to eclogite. Basalt floats on Earth’s mantle, but the heavier eclogite sinks into it. All over the world, the eclogite tore away from the basalt plateaus and sank into Earth’s hot mantle. Vast amounts of magma liquefied from the eclogite slabs as they sank into the hot mantle. This phenomenon is called partial melting, and it resembles what happens to cheese in a microwave oven. Solid cheese separates into melted fat and hard milk solids. The eclogite is the leftover solid cheese; the liquid magma is the melted fat. This magma rose through the basalt and formed 50% of what would become North America’s continental crust. But in the Archean eon, these pieces were still widely scattered on the planet.
In the late Archean eon, the plates of Earth’s crust may have continued to move at a relatively high speed. Evidence of these wild times can be found in the ancient core of North America. The scars of tectonic events appear as rock outcrops throughout the part of northern North America called the Canadian Shield. One example of this kind of scar, a greenstone belt, may be the mangled remains of ancient island arcs or rifts within continents. Gold and chromium are found in the greenstone belts, and deposits of copper, zinc, and nickel. Formations of ironore also began to form in the Archean eon, and fossils of microscopic cyano–bacteria–the first life on Earth—are found imbedded in them.
North America in the Proterozoic eon
North America’s little Archean continents slammed together in a series of mountain–building collisions. The core of the modern continent was formed 1,850 million years ago when five of these collisions occurred at once around northeastern Canada. This unified piece of ancient continental crust, called a craton, lies exposed at the surface in the Canadian Shield, and forms a solid foundation under much of the rest of the continent.
In the two billion years of the Proterozoic eon (2,500–570 million years ago), North America’s geologic setting became more like the world as we know it. The cores of the modern continents were assembled, and the first collections of continents, or supercontinents, appeared. Life, however, was limited to bacteria and algae, and unbreatheable gases filled the atmosphere. Rampant erosion filled the rivers with mud and sand, because no land plants protected Earth’s barren surface from the action of rain, wind, heat, and cold.
Sometimes tectonic stresses pulled the forming continents apart, creating cracks hundreds of miles or kilometers long in the crust. These cracks quickly filled with upwellingmagma to form dikes of solid rock. There are so many of these dikes of black rock that they are collectively called dike swarms.
Rich accumulations of both rare and common metallic elements make Proterozoic rocks a significant source of mineral wealth for North America, as on other continents. Chromium, nickel, copper, tin, titanium, vanadium, and platinum ores are found together in the onion–like layers of crystallized igneous rocks called layered intrusions. Greenstone belts are mined for copper, lead, and zinc, each of which is mixed with sulfur to form a sulfide mineral. Sulfide minerals of lead and zinc are found in limestones formed in shallow seas, while mines in the ancient continental river and delta sediments uncover buried vanadium, copper, and uranium ores.
Most of the steel framework for buildings and machines and tools comes from the processing of a rich and peculiar legacy of the Precambrian environment. Volcanos under the seas of Archean and Proterozoic time erupted huge amounts of ferric iron (Fe2+) into water filled with dissolved oxygen. The iron minerals that formed from the reaction of ferric iron and oxygen, hematite and iron hydroxides and sulfides, settled gently on the floors of lakes and quiet seas, season after season, for more than two billion years. The layers of ironminerals and chert formed amazing evenly striped rocks which have provided the world with its iron for more than a century. These banded iron formations are found in Greenland, Canada, and the Mesabi Range of Minnesota.
The banded iron formations disappear from the rock record at around 1.7 billion years ago, about the same time that oxides (minerals formed by reaction with oxygen) appeared abundantly in stream deposits. Some geologists theorize that previous to 1.7 billion years ago, oxygen was busy oxidizing iron in the sea to enter the atmosphere, and when the iron supply ran out, then the oxygen–rich atmosphere bubbled up out of the sea.
Somewhat similar to a continent–sized zipper, a huge rift opened from Kansas to Michigan’s upper peninsula around 1,150 million years ago. Its tectonic activity shut down before tearing the continent in half, but left a trough 93 mi (150 km) wide filled with up to 10 mi (15 km) of stacked basalt lava flows and stream sediments. The rift is exposed today in the Keweenaw peninsula in upper Michigan. It once contained giant boulders of pure copper, some weighing several tons.
During the middle to late Proterozoic eon, continental collisions attached new pieces of continental crust to North America’s southern, eastern, and western borders. Between 30% and 40% of North America joined the continent in the Proterozoic. The crust underlying the continental United States east of Nevada joined the craton, as well as the crust underlying the Sierra Madre Occidental of Sonora, Chihuahua, and Durango in Mexico. The Mazatzal Mountains, whose rootoutcrop in the Grand Canyon’s inner gorge, rose in these mountain–building times in southern and central North America.
Phanerozoic time
North America experienced the sea washing over its boundaries many times during the three billion–plus years of its Archean and Proterozoic history. Life had flourished in the shallow tidewater. Algae, a long–term resident of North America, was joined later by worms and other soft–bodied animals. Little is known of early soft–bodied organisms, because they left no skeletons to become fossils. Only a handful of good fossils remain from the entire world’s immense Precambrian rock record.
Then, about 570 million years ago, several unrelated lineages of shell–bearing sea animals appeared. This was the beginning of the Phanerozoic eon of earth history, which has lasted from 570 million years ago to the present day. Vast seas covered much of North America in the early Phanerozoic, their shorelines changing from one million–year interval to the next. The seas teemed with creatures whose bones and shells we have come to know in the fossil record. These oceanic events are memorialized in the layers of stone each sea left behind, lying flat in the continent’s heartland and folded and broken in the cordilleras. Geologists have surveyed the stacked sheets of stone left by ancient North American seas and have made maps of the deposits of each continental sea. The stacked layers are divided into sequences, each named for the sea that laid it down. Each sequence consisted of a slow and complex flooding of the continent. Sea level mountain uplift, the growth of deltas, and other factors continually changed the shape of the continental sea.
Eastern and southern borders of North America
The eastern coast of North America was once part of an ancient “Ring of Fire” surrounding an ocean that has disappeared forever from Earth. From Greenland to Georgia, and through the Gulf coast states into Mexico, the collision of continents raised mountains comparable to the Himalayas and Alps of today. Several ranges were raised up on the eastern border of North America between 480–230 million years ago.
The Taconic mountains rose 480 million years ago, wrinkled under pressure like the hood of a wrecked car, from Maryland to the Gaspe Peninsula of Quebec. The compressed rocks from this mountain–building event are exposed in the Taconic Range of New York, and in eastern Pennsylvania. But by 410 million years ago the peaks that had towered over the east coast had been eroded away, and the sea washed over their exposed roots and covered them with level deposits of limestone. As these mountains wore down, the resulting sediment filled a shallow sea basin running from New York southward to Alabama, in layers up to 1,000 ft (300 m) thick.
Another collision about 450 million years ago created the Acadian mountain range, whose roots are exposed today in Newfoundland. These mountains began to be torn down by rain and wind, and by the time they had worn down to nothing, more than 63,000 cubic miles of sediment made from them had been dumped into the shallow continental sea between New York and Virginia–about the same amount of rock as the Sierra Nevada mountains of today. The bones of amphibians, the first land animals, are found in the rocks laid down by the streams of East Greenland.
The sleepless crust under North America’s Pennsylvanian–age borders tossed and turned in complex ways. Three hundred million years ago, North America sat on the equator, its vast inland sea surrounded by rain forests whose fossilized remains are the coal deposits of the eastern United States. Small mountain ranges rose out of the sea that covered the center of the continent in Colorado, Oklahoma, and Texas. The Ouachitas stood in the Gulf coast states, the last great mountain range to stand there. In the eastern United States, the Allegheny mountain range stood where the Acadian and Taconic ranges had stood before.
The Ouachitas welded South America to the Gulf coast, at roughly the same time as the Alleghenies welded the East coast of North America to West Africa. The Ouachitas and Alleghenies stretched, unbroken, all the way around the eastern and southern coasts of North America. This joining of the world’s continents formed Pangaea, the most recent supercontinent in geologic history. Pangaea’s 150 million year history ended with the birth of the Atlantic Ocean and the separation of North and South America. As South America and Africa tore away from North America, Florida was left behind, attached to the intersection of the Allegheny and Ouachita mountains. Another legacy of this cracking of Earth’s crust is the New Madrid fault, which runs through the North American Plate under the Mississippi valley.
Western border of North America
The tectonic story begun on the western border of North America around 340 million years ago continues in the present day. Land masses created far away from North America began to collide with the continent. Off the western coast, the tectonic forces began moving in a new direction, and a long quiet interval came to an end. These are some of the phenomena that resulted:
Around 340 million years ago, an offshore island arc, called the Antler Arc, struck the shores about where Nevada and Idaho now are (then the westernmost part of the continent), extending the shoreline of North America a hundred miles westward.
By 245 million years ago, the beginning of the age of dinosaurs, another island arc had run into the American west. The Golconda Arc added a Sumatra–sized piece of land to North America, and the continent bulged out to present–day northern California.
After the Golconda Arc piled onto the West Coast of that time, the crust broke beneath the continent’s border, and the ocean’s plate ran under North America’s west coast like a speeding low–slung sport coupe might run under the rear bumper of a tractor–trailer. A continental arc was born around 230 million years ago in western North America, and its volcanos have been erupting frequently from the dawn of the age of dinosaurs (the Mesozoic era) until today.
Several more island arcs struck western North America since the middle Jurassic period. The granite mountains of the Sierra Nevada are the roots of one of these island arcs. Landmasses created on the Pacific Plate have been scraped off it like the roof of the sports coupe mentioned earlier would be scraped off as it crammed itself under the rear bumper of a tractor–trailer. This mechanism is the origin of the west coast’s ranges, the Cascades, and much of British Columbia and Alaska’s southern coast.
A range of fault block mountains rose far inland as the continent was squeezed from west to east. The Sevier mountains stood west of the Cretaceous period’s interior seaway, in what is now Montana, Idaho, Nevada, and Utah. The dinosaurs of that time (80–130 million years ago) left their tracks and remains in the mud and sand worn off these mountains.
In the same manner as large island chains were carried to North America on moving plates of oceanic crust, small pieces of land came to the coasts in this way as well. Numerous “exotic terrains,” impacting on the western coasts during the Mesozoic and Cenozoic eras, added large areas now covered by British Columbia, Washington, Oregon, California, and Mexico. These little rafts of continental crust were formed far from their present location, for the fossils in them are of creatures that lived halfway around the world–but never in North America. A sizeable piece of continental crust–southern Mexico as far south as the Isthmus of Tehuantepec–joined northern Mexico between 180–140 million years ago.
Interior West
Starting 80 million years ago, new forces began to act on the inland west. Geologists do not know exactly what happened beneath the crust to cause these changes, but the features created on the surface by tectonic action underneath the crust are well known.
At the same time as the Sevier mountains ceased to rise, a similar range, facing the opposite direction, began to move upward. Earth’s upper crust beneath the Rocky mountain states was shoved westward in the Laramide orogeny, lifting the Rocky mountains for the first time.
These first modern Rocky Mountains drained the continent’s last great shallow sea of inland North America as they rose. Huge mountains now stood in places where seas had rolled over Colorado, Wyoming, Utah, Idaho, Montana, and Alberta. In Mexico, the Laramide orogeny raised the Sierra Madre Occidental, and formed the mineral deposits that enrich Sonora, Chihuahua, Durango, and Zacatecas. In Colorado, Wyoming, and neighboring states, the Rocky Mountains began to erode away, and by 55 million years ago, the first Rockies had disappeared from the surface—the mountains’ roots were buried in sediment from the eroded mountain tops. More recent uplift again exposed the Rockies, and ice age glaciers sculpted their tops into today’s sharp peaks.
Twenty–five million years ago, after a quiet interlude, North America’s western continental arc awoke, and its abundant volcanos again added new rock to the continent from British Columbia to Texas and down the mountainous spine of Mexico. The only area in the Southwest in which volcanos were uncommon was the Colorado Plateau, whose immunity to the tectonic forces around it is still a mystery. Around the borders of the Colorado Plateau’s remarkably thick crust, one volcanic catastrophe after another covered the land. In this time the San Juan mountains were formed in Colorado. The Rocky Mountains began to slide westward and rose again on the thrust faults beneath them.
Ten million years ago, the Great Basin area of the United States was much shorter when measured east to west than it is today. It was then a mountainous highland. Some geologists propose that Nevada was an alpine plateau like Tibet is today—perhaps more than 10,000 ft (3,048 m) high. Starting then and continuing for five million years, this area began to be pulled apart. Long faults opened in the crust, and mountain–sized wedges slowly fell between ridges that were still standing on the unbroken basement rock miles below. Sediment from the erosion of these new ridges filled the valleys, enabling the valleys to become reservoirs of underground water, or aquifers. The low parts got so low that the area is indeed a basin; water does not flow out of it. Some geologists believe that the Basin and Range province stretches around the Colorado Plateau, into Texas, and extends down the Sierra Madre Occidental as far south as Oaxaca.
Another kind of pulling–apart of the continent happened in New Mexico’s Rio Grande rift. As at the Keweenaw rift a billion years before, tectonic forces from beneath Earth’s crust began pulling the surface apart just as east Africa is being pulled apart today. The broad rift’s mountainous walls eroded, and the sediment from that erosion piled up in the ever–widening valley. A new ocean was about to be formed in the southwest. Lava poured from fissures in the crust near Taos, New Mexico, filling the valley floor. Also like the Keweenaw rift, the Rio Grande rift stopped growing after a few million years, as the tectonic processes ceased pulling the continent apart. The modern Rio Grande was born as a consequence of this rift, and still runs through the rift valley.
A cataclysmic volcanic event happened in Oregon and Washington 17 million years ago. For an unknown reason, perhaps a disturbance deep in Earth’s mantle, or a meteor impact, lava began pouring out of cracks in Earth. So much lava poured onto the surface at once that it ran from southeastern Oregon down the Columbia river valley to the Pacific Ocean. Huge cracks in the ground called fissures flooded broad areas with basalt lava over about 500,000 years. This flood of basalt is called the Columbia river plateau. A hot spot, or an upwelling of molten rock from Earth’s mantle, appears to have caused the Columbia River plateau. As the North American plate moved westward between then and now, the hot spot stayed in one place, scorching holes in Earth’s crust under Idaho and erupting the lava that makes the Snake River Plain a fertile farmland. This hot spot is assumed to be the heat source that powers the geysers of Yellowstone National Park.
Arctic region
In the early Jurassic period, 200 million years ago, the northernmost edge of North America tore away from the continent and began rotating counterclockwise. This part of the continent came to rest to the northwest of North America, forming the original piece of Alaska–its northernmost mountains, the Brooks Range. In the late Cretaceous period, the farthest part of this landmass from North America struck the edge of Siberia, and became the Chukotsk Peninsula. The remaining land–mass of Alaska joined North America bit by bit, in the form of exotic terrains. The Aleutians, a classic island arc, formed in the Tertiary period. The about 40 active volcanos of the Aleutians have erupted numerous times in the twentieth century, including several eruptions in the last decade from Mt. Augustine, Pavlov, Shishaldin, and Mt. Redoubt.
The Ice Age in North America
For reasons that are not yet fully understood, Earth periodically enters a time of planet–wide cooling. Large areas of the land and seas are covered in ice sheets thousands of feet thick, that remain unmelted for thousands or hundreds of thousands of years. Today, only Greenland and Antarctica lie beneath continent–sized glaciers. But in the very recent geologic past, North America’s northern regions, including the entire landmass of Canada, were ground and polished by an oceanic amount of water frozen into a single mass of ice. This ice began to accumulate as the planet’sweather cooled, and began to stay frozen all year round. As it built up higher and higher, it began to move out from the piled–high center, flowing while still solid.
Vast amounts of Canadian soil and rock, called glacial till, rode on the ice sheets as they moved, or surfed slowly before the front of the ice wall. Some of the richest farmland in the United States midwest and northeast arrived in its present location in this way–as well as boulders that must be removed from fields before plowing. In the unusual geographic conditions following the retreat of the ice sheets, barren soil lay on the landscape, no longer held down by the glacier. Windstorms moved tremendous amounts of this soil far from where the glacier left it, to settle out of the sky as a layer of fertile soil, called loess in German and English. Loess soils settled in the Mississippi and Missouri valleys, and also Washington, Oregon, Oklahoma, and Texas.
This continental glaciation happened seven times over the last 2.2 million years. Warm intervals, some of them hundreds of thousands of years long, stretched between these planetary deep–freezes. Geologists do not agree whether the ice will return or not. Even if the present day is in a warm period between glaciations, tens or hundreds of thousands of years may elapse before the next advance of the ice sheets.
Modern geologic events in North America
California lies between two different kinds of plate boundaries. To the south, the crust under California is growing; to the north it is shrinking. The part of California that sits on the Pacific plate between these two forces is moved northward in sudden increments of a few feet, which are felt as earthquakes. A few feet at a time, in earthquakes that happen every few decades, the part of California west of the San Andreas Fault will move northward along the coast.
Active faults also exist elsewhere in the United States, in the midwest and in South Carolina. The last sizeable earthquakes in these regions occurred more than a hundred years ago, and geologists assume that earthquakes will probably occur within the next hundred years. The Pacific Northwest and Alaska, sitting atop active tectonic environments, will
KEY TERMS
Archean eon —The interval of geologic time from 3.8 billion years ago to 2.5 billion years ago.
Canadian shield —The oldest part of North America, made of rocks formed between 3.8 and 2.5 billion years ago, that underlies much of northern and eastern Canada.
Collisional mountain belt —A mountain range, like the Appalachians, caused by one continent running into another continent.
Continental arc —A volcanic mountain range, like the Cascades, that forms on the tectonically active edge of a continent, over a subduction zone.
Craton —A piece of a continent that has remained intact since Earth’s earliest history, and which functions as a foundation, or basement, for more recent pieces of a continent.
Fault block mountains —A mountain range, like the Front Range of the Rocky Mountains, caused by horizontal forces that squeeze a continent, fracturing its crust and pushing blocks of crust up to form mountains. Also, a mountain range, like the Shoshone Range of Nevada, caused by horizontal forces that stretch a continent, fracturing the crust and causing some blocks of crust to sink down, leaving other blocks standing at high elevations above the valleys.
Glacial till —Rocks, soil and other sediments transported by a glacier then deposited along its line of farthest advance.
Island arc —A volcanic mountain range, like the Aleutians, built on a tectonically active plate boundary in the sea, which appears as islands.
Phanerozoic eon —The interval of geologic time beginning 570 million years ago, the rocks of which contain an abundant record of fossilized life.
Plate tectonics —The interactions of the plates of Earth’s crust, which float on top of Earth’s mantle, and whose movements through geologic time have caused the major features of the continents.
Precambrian era —The combined Archean and Proterozoic eons, the first four billion years of Earth’s history.
Proterozoic eon —The interval of geologic time beginning 2.5 billion years ago and ending 570 million years ago.
certainly be shaken by earthquakes for millions of years to come. The Great Basin, the western Rocky Mountains, and the United States northeast are all considered tectonically active enough for earthquakes to be considered possible.
North America’s volcanic mountain ranges, the Cascades, and the relatively recent Mexican volcanic belt, have erupted often in the recent geologic past. These mountains will certainly continue to erupt in the near geologic future.
Resources
BOOKS
Colbert, E., ed. Our Continent. Washington, DC: The National Geographic Society, 1976.
Hancock, P. L., and Skinner B. J., eds. The Oxford Companion to the Earth. Oxford: Oxford University Press, 2001.
Menzies, Gavin. 1421: The Year China Discovered America. New York: William Morrow & Co., 2003.
PERIODICALS
Bokelmann, G.H.R. “Which Forces Drive North America?” Geology 30, no. 11 (2002): 1027–1030.
Clinton Crowley
North America
NORTH AMERICA
In the seventeenth and eighteenth centuries, France's North American colonies stretched westward from the Gulf of St. Lawrence to the Great Lakes and southward from the Great Lakes to the Gulf of Mexico. The early proprietary governments gave way to a royal regime in the mid-seventeenth century, although the proprietary model was resuscitated on a limited basis in the eighteenth century. Forms of social organization varied from colony to colony, but everywhere there were new realities, belying the characterization of New France as an archaic feudal society. Economically the colonies differed from one another as well, but in general the absence of a labor-intensive staple such as tobacco or sugar precluded large-scale immigration. Recent estimates of the volume of immigration range from 33,500 for the St. Lawrence Valley to 7,000 for the Canadian Maritimes and 14,000 for Louisiana (half of them African slaves). While these figures are larger than was originally thought, the staying power of the immigrants—most often single young men from urban backgrounds—was notoriously poor. At the time of the British conquest, New France in its entirely had fewer than 100,000 European or African inhabitants, compared to nearly 2 million in British North America.
THE PROCESS OF COLONIZATION
Although there were abortive attempts to found colonies in Canada and Florida in the mid-sixteenth century, the first permanent French settlements in North America were Acadia in 1604 and Quebec in 1608. The initiative for both came from Pierre Du Gua de Monts, an officer who was then the exclusive proprietor of New France. The charter he received from Henry IV granted him seigneurial rights and a commercial monopoly over eastern North America from Philadelphia to Newfoundland, in return for which he agreed to shoulder the expenses of colonization.
De Monts abandoned the settlement of Port Royal (today Annapolis Royal in Nova Scotia) in 1607; however, French Acadia survived owing to the first subinfeudation practiced within a proprietary colony. Using his authority as proprietor, De Monts granted the land as a seigneurie to Jean Biencourt de Poutrincourt, a nobleman who had accompanied the first expedition to Port Royal. With Poutrincourt, settlement resumed and colonization entered a new phase. From the responsibility of a single overlord in possession of a commercial monopoly, it became the shared responsibility of the overlord and his seigneur. The return on the latter's investments would come not from trade but from seigneurial revenues (feudal rents collected from peasant farmers), so a successful enterprise would require agricultural settlement.
Unfortunately for the colony, Poutrincourt died a pauper in 1615, bequeathing his seigneurie to his equally impoverished son Biencourt. At Biencourt's death in 1623, Port Royal remained a trading post with no more than twenty year-round residents, none of them women.
Meanwhile the Canadian monopoly passed from de Monts, who lost it as the result of merchant complaints, to a succession of members of the upper nobility. All but one of the new proprietors (now known as viceroys) worked in tandem with a company of merchants, but colonization proceeded slowly nonetheless. In 1627, when Cardinal Richelieu revoked the most recent charter, Quebec had a total population of eighty-five, of whom only two dozen were true settlers.
Richelieu, who was anxious to transform the fledgling settlements into an important colony, created the Company of New France, more commonly known as the Company of the Hundred Associates. Differing from earlier companies in scope rather than structure, it received a perpetual monopoly on the fur trade and a fifteen-year monopoly on all other trade except the fisheries. During those fifteen years, it agreed to transport four thousand French Catholics of both sexes to New France. Yet the new proprietors experienced disastrous luck from the beginning. Their first fleet, which departed France with three hundred colonists, was captured by the British, who went on to occupy Quebec from 1629 to 1632. After the occupation, financial constraints obliged the company to subcontract the monopoly. Colonization continued under the aegis of subcontractors and seigneurs, but in 1663, when Louis XIV revoked the company's charter, New France had barely 3,500 French inhabitants. Moreover, several hundred of them lived in Acadia, under British occupation since 1654.
Louis XIV, seconded by minister Jean-Baptiste Colbert, brought the colony directly under royal administration. In the first ten years of royal control, Canada received about four thousand new colonists at the king's expense, after which funds and interest waned again. Nonetheless, New France continued to expand geographically in the first half of the eighteenth century. Acadia, returned to France by treaty in 1667, was ceded back to Britain in 1713. In reaction France moved to colonize her remaining territories in the Gulf of St. Lawrence: Cape Breton Island and Île Saint-Jean, now Prince Edward Island. At the same time, the French moved westward into the Great Lakes, founding Detroit in 1701, and southward into the Mississippi Valley. The Illinois country, an extension of the Great Lakes via the Mississippi and Illinois rivers, was the only French colony in North America established spontaneously by colonists rather than as a result of royal policy. Louisiana, on the other hand, was a royal creation designed to prevent the British or Spanish from controlling the mouth of the Mississippi. Founded in 1699 by Pierre Le Moyne d'Iberville, it was conceded to a proprietor, financier Antoine Crozat, in 1712, then transferred to John Law's Company of the Occident (later called the Company of the Indies) in 1717. The collapse of Law's system saw the return of royal rule in the 1720s as well as the transfer of the seat of government from Mobile to New Orleans.
POLITICAL ORGANIZATION
New France arose coincidentally with France's absolutist state and had substantially the same architects. Both Richelieu and Colbert wanted to increase the power of France by means of a dynamic colonial empire. As a result of their attentions, New France would become a laboratory of state-of-theart political and social practices.
The government of French North America was always authoritarian. Before 1627 there were five different proprietors or viceroys, all of whom delegated their powers to the same individual in Quebec, Samuel de Champlain (c. 1567–1635). Champlain continued to administer New France until his death in 1635, in the final years as Richelieu's lieutenant. His successors (appointed by the king upon recommendation of the Hundred Associates) gained the formal title of governor of New France. There were also regional governors in Acadia, Three Rivers, and Montreal, the latter appointed by the Notre Dame Society, the missionary organization that founded the settlement and served as its seigneur. Finally, in 1647 the crown established a Council in Quebec consisting of the governor general, the governor of Montreal, and the Jesuit superior; it was expanded to seven members the following year.
With the imposition of royal rule in 1663, the government acquired the contours it would retain until the end of the French regime. The king appointed not only a governor general whose primary tasks were military and diplomatic, but an intendant responsible for civil administration. A new Sovereign Council (later called Superior Council) became the highest court in the land. It brought together the governor general, the intendant, the bishop, and five (later seven, then twelve) additional councillors. In theory the authority of the governor general and intendant extended beyond the St. Lawrence, but as New France expanded, the outlying colonies gained de facto administrative independence. In Île Royale (Cape Breton) and Louisiana the governors took orders directly from France, the commissaires ordonnateurs were intendants in all but name, and the Superior Councils filled the same function as the council in Quebec.
Because venality of office did not exist in New France, all high-level administrators served at the king's pleasure. The colonial government was thus a purer expression of French absolutism than its metropolitan counterpart. Some historians have judged this regime harshly for stifling freedom and initiative, while others have praised its efficiency and paternalism. Yet it is noteworthy how often arbitrary power worked, in the colonial context, to level the traditional orders of the ancien régime. Indeed, many administrative decisions reflect the almost physiocratic repugnance for intermediary bodies and paternalist regulation that historians associate with enlightened despotism.
COLONIAL SOCIETY
Traditionally, historians portrayed New France as a backward feudal society, but that interpretation has been challenged, or at least qualified significantly, in recent decades. To be sure the three estates—clergy, nobility, and commons—were recognized in French North America, but privilege was largely meaningless there since even commoners owed no taxes. Social advancement could also be more rapid in the colonies. Nicolas Juchereau, the son of a merchant turned Canadian seigneur, acceded to the nobility in 1692, a century before his cousins in the French branch of the family. In the St. Lawrence Valley, the seigneurial system did siphon off a larger part of the agricultural surplus as time went on. On the other hand, seigneurialism in Acadia existed largely on paper before succumbing to British occupation. There was no seigneurial system and virtually no agriculture on Île Royale, while Louisiana and the Illinois country had plantations worked by African and Indian slaves.
Despite their seigneurs, Canadian habitants (a term adopted by colonial farmers to distinguish themselves from mere peasants) managed to speculate in land, practice a highly individualist agriculture, and even occasionally achieve upward social mobility. In the towns tradesmen were free to pursue their own interest, since there were no guilds, and corporatist association was strictly limited. New France boasted a number of successful businesswomen, not all of them widows or religious.
New France was also a multicultural society. There were reserves for Christian Indians right in the heart of the St. Lawrence Valley, where domiciled Indians made up about 10 percent of the colonial population. Several hundred slaves of either Indian or African origin labored in Montreal, as did hundreds of captives taken from the British colonies during the French and Indian Wars.
Beyond the St. Lawrence Valley, much of New France remained, in essence, Native-controlled territory. In the Great Lakes, French sovereignty was represented only by the young agricultural settlement at Detroit, together with widely scattered trading, missionary, and military outposts. Although Louisiana had a population of four thousand Europeans and five thousand Africans by the mid-eighteenth century, at that time there were still some seventy thousand Indians living in the lower Mississippi Valley. Intercultural relations were numerous and are symbolized by the coureurs de bois, French fur traders who ventured into Indian country to obtain their wares. Numbering in the hundreds as early as the 1680s, the coureurs de bois were Frenchmen who voluntarily adopted an Indian way of life. During their voyages they relied upon Native technologies, Native languages, and the services (sexual as well as economic) of Native women. It was the coureurs de bois who initiated French settlement in the Illinois country, through their marriages to Indian women beginning in the 1690s.
ECONOMIC DEVELOPMENT AND IMMIGRATION
Despite the importance of the fur trade (a vogue for felt hats created demand for beaver pelts in Europe), New France never met the economic expectations of its promoters. Neither fur nor cod, the other Canadian staple, required a large colonial labor force, so from the outset transporting immigrants was a financial liability rather than a source of profit. Only when the state or state-supported companies intervened did immigration attain significant proportions. Even then the rate of permanent settlement was low, so demographic growth was gradual. In the absence of large colonial populations, agricultural and industrial development occurred slowly, limiting demand for further immigration.
At Richelieu's behest, the Company of the Hundred Associates arranged for the passage of an estimated 7,300 people to New France, probably 4,700 to the St. Lawrence Valley and 2,600 to Acadia. Many of them, however, moved on to other destinations, roughly half of those sent to the St. Lawrence and nearly everyone in Acadia. While the unstable political situation was a factor, especially in Acadia, so was the nature of the labor supply. Apart from a few of the seigneurs, who recruited in situ among people known to them in France, most of the company's recruiting agents worked out of La Rochelle, Dieppe, or Rouen, major towns with large populations of single migrant laborers. What historians call "metropolitan migration," the sort least likely to have staying power, clearly predominated in this migration stream. (The typical metropolitan migrant was a young urban tradesman seeking employment.)
The immigrants of the period 1663–1673 included eight hundred marriageable women, recruited largely from charity hospitals. Thanks to these filles du roi (king's daughters), the immigrant sex ratio became more balanced, fostering population growth through natural increase. In the eighteenth century, most royal recruits for Canada were either soldiers or prisoners. The St. Lawrence Valley received perhaps 33,500 immigrants in all, of whom no more than 10,000 founded families in the colony. An estimated 7,000 French immigrants passed through the Canadian Maritimes, yet today's Acadians descend from only a few hundred founding families.
In Louisiana, John Law's Company of the Occident pursued the most dynamic immigration policy in the history of New France. From 1717 to 1720, it deported over 1,400 men and women from prisons and large cities, where they had been arrested as vagabonds. Although deportations ceased in response to riots against "Louisiana slavery" (an ironic reference since the first African slaves were also shipped to Louisiana in these years—two thousand between 1719 and 1721), the company blanketed France with propaganda promoting immigration. The campaign had limited success there due to the colony's already poor reputation in the Atlantic ports that were the natural reservoirs of colonial migration. On the other hand, translated into German, Law's brochures created a sensation in the Rhine Valley, where four thousand people packed their bags for Louisiana. These recruits were "provincial migrants" fleeing rural areas undergoing agricultural modernization. They were more likely to travel in families and, like religious refugees, more apt to settle than footloose urban laborers. Had Richelieu and Louis XIV been as tolerant of foreigners and Protestants as the Company of the Occident, perhaps the return rate of immigrants to Canada would have been lower.
By the mid-eighteenth century, the St. Lawrence Valley was a land of self-sufficient family farms that exported surplus wheat to Île Royale and the Caribbean. Acadian farms were also prosperous, although they no longer belonged to New France. Illinois farmers, who produced foodstuffs for Louisiana, used the labor of African slaves, as did Louisiana's fledgling tobacco and indigo plantations. Yet most of Louisiana's small population still participated in the frontier exchange economy, a patchwork of commercial and subsistence endeavors. The most vigorous colonial economy was that of Île Royale, whose capital, Louisbourg, quickly became both a major base for the North Atlantic fishery and a busy entrepôt in the triangular trade among Europe, North America, and the West Indies, in rivalry with New England.
BRITISH CONQUEST
After the loss of Acadia to Britain in 1713, the next military setback for New France occurred during the War of the Austrian Succession (1740–1748). In 1745 New England forces, with the help of the Royal Navy, laid siege to Louisbourg, which surrendered after a seven-week bombardment. Although Île Royale was returned to France by treaty in 1748, New Englanders were furious, and their complaints helped bring about an all-out British offensive against New France during the Seven Years' War (1756–1763).
The most controversial act of the conquest was actually a prelude to it. In 1755 the British expropriated and deported the Acadians, despite their declared neutrality. Some deportees landed in England, while others were scattered across the thirteen colonies. More than one thousand victims of this Grand Dérangement (Great Disturbance) eventually made their way to Louisiana after the war.
Louisbourg fell a second time in 1758, and Quebec followed suit after the Battle of the Plains of Abraham, a dramatic but successful gamble on the part of British commander James Wolfe, in 1759. By the Treaty of Paris (1763), the French ceded Louisiana to Spain and the rest of New France to Britain. They retained only fishing rights on the Newfoundland coast and two tiny islands, St. Pierre and Miquelon, in the Gulf of St. Lawrence. Today these two islands, still under French sovereignty, are all that remains of France's empire in North America.
See also Austrian Succession, War of the (1740–1748) ; British Colonies: North America ; Colbert, Jean-Baptiste ; Colonialism ; Fur Trade: North America ; Law's System ; Louis XIV (France) ; Richelieu, Armand-Jean Du Plessis, cardinal ; Seven Years' War (1756–1763) .
BIBLIOGRAPHY
Boleda, Mario. "Trente mille Français à la conquête du Saint-Laurent." Histoire sociale/Social History 23 (1990): 153–177. The author has raised this estimate of immigration to 33,500 based on his current research.
Carpin, Gervais. Le réseau du Canada: Étude du mode migratoire de la France vers la Nouvelle France (1628–1662). Sillery, Quebec, and Paris, 2001.
Charbonneau, Hubert, et al., with the collaboration of Réal Bates and Mario Boleda. The First French Canadians: Pioneers in the St. Lawrence Valley. Translated by Paola Colozzo. Newark, Del., and London, 1993.
Choquette, Leslie. Frenchmen into Peasants: Modernity and Tradition in the Peopling of French Canada. Cambridge, Mass., and London, 1997.
Dechêne, Louise. Habitants and Merchants in Seventeenth-Century Montreal. Translated by Liana Vardi. Montreal and Buffalo, 1992.
Eccles, W. J. France in America. New York, 1972.
Greer, Allan. The People of New France. Toronto and Buffalo, 1997.
Griffiths, Naomi E. S. The Contexts of Acadian History, 1686–1784. Montreal and Buffalo, 1992.
Krause, Eric, Carol Corbin, and William O'Shea, eds. Aspects of Louisbourg: Essays on the History of an Eighteenth-Century French Community in North America. Sydney, Nova Scotia, 1995.
Moogk, Peter. La Nouvelle France: The Making of French Canada. A Cultural History. East Lansing, Mich., 2000.
Moore, Christopher. Louisbourg Portraits: Life in an Eighteenth-Century Garrison Town. Toronto, 1982.
Usner, Daniel. Indians, Settlers, and Slaves in a Frontier Exchange Economy: The Lower Mississippi Valley Before 1783. Chapel Hill, N.C., 1992.
White, Richard. The Middle Ground: Indians, Empires, and Republics in the Great Lakes Region. Cambridge, U.K., and New York, 1991.
Leslie Choquette
North America
North America
The landmass occupied by the present-day countries of Canada, the United States, and the Republic of Mexico make up North America. Greenland (Kalaallit Nunaat), an island landmass to the northeast of Canada, is also included in North America, for it has been attached to Canada for almost two billion years.
Plate tectonics is the main force of nature responsible for the geologic history of North America. Over ages of geologic time , the plates have come together to form the continents, including North America. Other processes, such as sedimentation and erosion , modify the shape of the land that has been forged by platetectonics.
North American geologic history includes several types of mountain ranges as a result of plate tectonics . When the edge of a plate of Earth's crust runs over another plate, forcing the lower plate deep into Earth's elastic interior, a long, curved mountain chain of volcanos usually forms on the forward-moving edge of the upper plate. When this border between two plates forms in the middle of the ocean , the volcanic mountains form a string of islands, or archipelago, such as the Antilles and the Aleutians. This phenomenon is called an island arc.
When the upper plate is carrying a continent on its forward edge, a mountain chain, like the Cascades, forms right on the forward edge. This edge, heavily populated with volcanos, is called a continental arc. The volcanic mountains on the plate border described above can run into a continent, shatter the collision area and stack up the pieces into a mountain range. This is how the Appalachians were formed. Imagine how high your school would reach if it were squeezed by bulldozers so it remained the same length east to west as it is now, but from north to south measured the width of a convenience store restroom. The result would be a tall wall of fractured rubble, and that is just what a collisional mountain belt is.
When a continent-sized "layer cake" of rock is pushed, the upper layers move more readily than the lower layers. The layers separate from each other, and the upper few miles of rock move on ahead, floating on fluid pressure between the upper and lower sections of the crust like a fully loaded tractor trailer gliding effortlessly along an icy road. The flat surface where moving layers of crust slide along the top of the layers beneath it is called a thrust fault , and the mountains that are heaved up where the thrust fault reaches the surface are one kind of fault block mountains. The mountains of Glacier National Park slid along the Lewis thrust fault over younger rocks , and out onto the Great Plains.
Another kind of fault block mountains comes from stretching of Earth's crust. A model of this kind of mountains could be made by compacting a 6-in (15-cm) thick layer of moist sand on top of a rubber (not rubberized) sheet. When the sheet stretches, mimicking the elastic properties of the lower crust, the sand will crack along lines perpendicular to the direction the sheet is being pulled. Some of the surface will remain the same height, and some blocks will slide down the sides of the blocks which remain stable. This is particularly noticeable if the top surface of the compacted sand has been dusted with powder. This is a model of the process that formed the mountains in the Basin and Range province.
Mountain ranges start being torn down by physical and chemical forces while they are still rising. North America has been criss-crossed by one immense range of mountains after another throughout its almost four-billion-year history.
A range of mountains may persist for hundreds of millions of years, like the Appalachians. On repeated occasions, the warped, folded rocks of the Appalachians were brought up out of the continent's basement and raised thousands of feet by tectonic forces. If mountains are not continuously uplifted, they are worn down by erosion in a few million years. In North America's geologic past, eroded particles from its mountains were carried by streams and dumped into the continent's inland seas, some of which were as large as the present-day Mediterranean. Those rivers and seas are gone from the continent, but the sediments that filled them remain, like dirt in a bathtub when the water is drained. The roots of all the mountain ranges that have ever stood in North America all still exist, and much of the sand and clay into which the mountains were transformed still exists also, as rock or soil formations.
Geologic history
North America in the Archean eon
North America was not formed in one piece, or at one time, the way a cake is baked from batter. Various parts of it were formed all over the world, at various times over four billion years, and were brought together and assembled into one continent by the endless process of plate tectonics. What is now called North America began to form in the first two and one-half billion years of Earth's history, a period of time called the Archean eon.
Some geologists speculate that Earth that created the oldest parts of North America barely resembled the middle-aged planet on which we live. The planet of four billion years ago had cooled enough to have a solid crust, and oceans of liquid water. But the crust may have included hundreds of small tectonic plates, moving perhaps ten times faster than plates move today. These small plates, carrying what are now the most ancient rocks, scudded across the oceans of a frantic crazy-quilt planet. Active volcanos and rifts played a role in rock formation on the Archean Earth. The oldest regions in North America were formed in this hyperactive world. These regions are in Greenland, Labrador, Minnesota, and Wyoming.
Earth changed over the next billion years. A sudden surge of continental construction created much of North America. Between three and four billion years ago, great basalt plateaus gradually built up under the oceans. As the planet cooled, the rock on the undersides of these plateaus changed from basalt to eclogite. Basalt floats on Earth's mantle, but the heavier eclogite sinks into it. All over the world, the eclogite tore away from the basalt plateaus and sank into Earth's hot mantle. Vast amounts of magma liquefied from the eclogite slabs as they sank into the hot mantle. This phenomenon is called partial melting, and it resembles what happens to cheese in a microwave oven. Solid cheese separates into melted fat and hard milk solids. The eclogite is the leftover solid cheese; the liquid magma is the melted fat. This magma rose through the basalt and formed 50% of what would become North America's continental crust. But in the Archean eon, these pieces were still widely scattered on the planet.
In the late Archean eon, the plates of Earth's crust may have continued to move at a relatively high speed. Evidence of these wild times can be found in the ancient core of North America. The scars of tectonic events appear as rock outcrops throughout the part of northern North America called the Canadian Shield. One example of this kind of scar, a greenstone belt, may be the mangled remains of ancient island arcs or rifts within continents. Gold and chromium are found in the greenstone belts, and deposits of copper , zinc, and nickel. Formations of iron ore also began to form in the Archean eon, and fossils of microscopic cyanobacteria-the first life on Earth—are found imbedded in them.
North America in the Proterozoic eon
North America's little Archean continents slammed together in a series of mountain-building collisions. The core of the modern continent was formed 1,850 million years ago when five of these collisions occurred at once around northeastern Canada. This unified piece of ancient continental crust, called a craton, lies exposed at the surface in the Canadian Shield, and forms a solid foundation under much of the rest of the continent.
In the two billion years of the Proterozoic eon (2,500-570 million years ago), North America's geologic setting became more like the world as we know it. The cores of the modern continents were assembled, and the first collections of continents, or supercontinents, appeared. Life, however, was limited to bacteria and algae , and unbreatheable gases filled the atmosphere. Rampant erosion filled the rivers with mud and sand, because no land plants protected Earth's barren surface from the action of rain, wind , heat, and cold.
Sometimes tectonic stresses pulled the forming continents apart, creating cracks hundreds of miles or kilometers long in the crust. These cracks quickly filled with upwellingmagma to form dikes of solid rock. There are so many of these dikes of black rock that they are collectively called dike swarms.
Rich accumulations of both rare and common metallic elements make Proterozoic rocks a significant source of mineral wealth for North America, as on other continents. Chromium, nickel, copper, tin, titanium , vanadium, and platinum ores are found together in the onion-like layers of crystallized igneous rocks called layered intrusions. Greenstone belts are mined for copper, lead , and zinc, each of which is mixed with sulfur to form a sulfide mineral. Sulfide minerals of lead and zinc are found in limestones formed in shallow seas, while mines in the ancient continental river and delta sediments uncover buried vanadium, copper, and uranium ores.
Most of the steel framework for buildings and machines and tools comes from the processing of a rich and peculiar legacy of the Precambrian environment. Volcanos under the seas of Archean and Proterozoic time erupted huge amounts of ferric iron (Fe2+) into water filled with dissolved oxygen . The iron minerals that formed from the reaction of ferric iron and oxygen, hematite and iron hydroxides and sulfides, settled gently on the floors of lakes and quiet seas, season after season, for more than two billion years. The layers of ironminerals and chert formed amazing evenly striped rocks which have provided the world with its iron for more than a century. These banded iron formations are found in Greenland, Canada, and the Mesabi Range of Minnesota.
The banded iron formations disappear from the rock record at around 1.7 billion years ago, about the same time that oxides (minerals formed by reaction with oxygen) appeared abundantly in stream deposits. Some geologists theorize that previous to 1.7 billion years ago, oxygen was busy oxidizing iron in the sea to enter the atmosphere, and when the iron supply ran out, then the oxygen-rich atmosphere bubbled up out of the sea.
Somewhat similar to a continent-sized zipper, a huge rift opened from Kansas to Michigan's upper peninsula around 1,150 million years ago. Its tectonic activity shut down before tearing the continent in half, but left a trough 93 mi (150 km) wide filled with up to 10 mi (15 km) of stacked basalt lava flows and stream sediments. The rift is exposed today in the Keewenaw peninsula in upper Michigan. It once contained giant boulders of pure copper, some weighing several tons.
During the middle to late Proterozoic eon, continental collisions attached new pieces of continental crust to North America's southern, eastern, and western borders. Between 30% and 40% of North America joined the continent in the Proterozoic. The crust underlying the continental United States east of Nevada joined the craton, as well as the crust underlying the Sierra Madre Occidental of Sonora, Chihuahua, and Durango in Mexico. The Mazatzal Mountains, whose rootoutcrop in the Grand Canyon's inner gorge, rose in these mountain-building times in southern and central North America.
Phanerozoic time
North America experienced the sea washing over its boundaries many times during the three billion-plus years of its Archean and Proterozoic history. Life had flourished in the shallow tidewater. Algae, a long-term resident of North America, was joined later by worms and other soft-bodied animals. Little is known of early soft-bodied organisms, because they left no skeletons to become fossils. Only a handful of good fossils remain from the entire world's immense Precambrian rock record.
Then, about 570 million years ago, several unrelated lineages of shell-bearing sea animals appeared. This was the beginning of the Phanerozoic eon of Earth history, which has lasted from 570 million years ago to the present day. Vast seas covered much of North America in the early Phanerozoic, their shorelines changing from one million-year interval to the next. The seas teemed with creatures whose bones and shells we have come to know in the fossil record. These oceanic events are memorialized in the layers of stone each sea left behind, lying flat in the continent's heartland and folded and broken in the cordilleras. Geologists have surveyed the stacked sheets of stone left by ancient North American seas and have made maps of the deposits of each continental sea. The stacked layers are divided into sequences, each named for the sea that laid it down. Each sequence consisted of a slow and complex flooding of the continent. Sea level mountain uplift , the growth of deltas, and other factors continually changed the shape of the continental sea.
Eastern and southern borders of North America
The eastern coast of North America was once part of an ancient "Ring of Fire" surrounding an ocean that has disappeared forever from Earth. From Greenland to Georgia, and through the Gulf coast states into Mexico, the collision of continents raised mountains comparable to the Himalayas and Alps of today. Several ranges were raised up on the eastern border of North America between 480-230 million years ago.
The Taconic mountains rose 480 million years ago, wrinkled under pressure like the hood of a wrecked car, from Maryland to the Gaspe Peninsula of Quebec. The compressed rocks from this mountain-building event are exposed in the Taconic Range of New York, and in eastern Pennsylvania. But by 410 million years ago the peaks that had towered over the east coast had been eroded away, and the sea washed over their exposed roots and covered them with level deposits of limestone. As these mountains wore down, the resulting sediment filled a shallow sea basin running from New York southward to Alabama, in layers up to 1,000 ft (300 m) thick.
Another collision about 450 million years ago created the Acadian mountain range, whose roots are exposed today in Newfoundland. These mountains began to be torn down by rain and wind, and by the time they had worn down to nothing, more than 63,000 cubic miles of sediment made from them had been dumped into the shallow continental sea between New York and Virginia-about the same amount of rock as the Sierra Nevada mountains of today. The bones of amphibians , the first land animals, are found in the rocks laid down by the streams of East Greenland.
The sleepless crust under North America's Pennsylvanian-age borders tossed and turned in complex ways. Three hundred million years ago, North America sat on the equator, its vast inland sea surrounded by rain forests whose fossilized remains are the coal deposits of the eastern United States. Small mountain ranges rose out of the sea that covered the center of the continent in Colorado, Oklahoma, and Texas. The Ouachitas stood in the Gulf coast states, the last great mountain range to stand there. In the eastern United States, the Allegheny mountain range stood where the Acadian and Taconic ranges had stood before.
The Ouachitas welded South America to the Gulf coast, at roughly the same time as the Alleghenies welded the East coast of North America to West Africa . The Ouachitas and Alleghenies stretched, unbroken, all the way around the eastern and southern coasts of North America. This joining of the world's continents formed Pangaea, the most recent supercontinent in geologic history. Pangaea's 150 million year history ended with the birth of the Atlantic Ocean and the separation of North and South America. As South America and Africa tore away from North America, Florida was left behind, attached to the intersection of the Allegheny and Ouachita mountains. Another legacy of this cracking of Earth's crust is the New Madrid fault, which runs through the North American Plate under the Mississippi valley.
Western border of North America
The tectonic story begun on the western border of North America around 340 million years ago continues in the present day. Land masses created far away from North America began to collide with the continent. Off the western coast, the tectonic forces began moving in a new direction, and a long quiet interval came to an end. These are some of the phenomena that resulted:
Around 340 million years ago, an offshore island arc, called the Antler Arc, struck the shores about where Nevada and Idaho now are (then the westernmost part of the continent), extending the shoreline of North America a hundred miles westward.
By 245 million years ago, the beginning of the age of dinosaurs, another island arc had run into the American west. The Golconda Arc added a Sumatra-sized piece of land to North America, and the continent bulged out to present-day northern California.
After the Golconda Arc piled onto the West Coast of that time, the crust broke beneath the continent's border, and the ocean's plate ran under North America's west coast like a speeding low-slung sport coupe might run under the rear bumper of a tractor-trailer. A continental arc was born around 230 million years ago in western North America, and its volcanos have been erupting frequently from the dawn of the age of dinosaurs (the Mesozoic era) until today.
Several more island arcs struck western North America since the middle Jurassic period. The granite mountains of the Sierra Nevada are the roots of one of these island arcs. Landmasses created on the Pacific Plate have been scraped off it like the roof of the sports coupe mentioned earlier would be scraped off as it crammed itself under the rear bumper of a tractor-trailer. This mechanism is the origin of the west coast's ranges, the Cascades, and much of British Columbia and Alaska's southern coast.
A range of fault block mountains rose far inland as the continent was squeezed from west to east. The Sevier mountains stood west of the Cretaceous period's interior seaway, in what is now Montana, Idaho, Nevada, and Utah. The dinosaurs of that time (80-130 million years ago) left their tracks and remains in the mud and sand worn off these mountains.
In the same manner as large island chains were carried to North America on moving plates of oceanic crust, small pieces of land came to the coasts in this way as well. Numerous "exotic terrains," impacting on the western coasts during the Mesozoic and Cenozoic eras, added large areas now covered by British Columbia, Washington, Oregon, California, and Mexico. These little rafts of continental crust were formed far from their present location, for the fossils in them are of creatures that lived halfway around the world-but never in North America. A sizeable piece of continental crust-southern Mexico as far south as the Isthmus of Tehuantepec-joined northern Mexico between 180-140 million years ago.
Interior West
Starting 80 million years ago, new forces began to act on the inland west. Geologists do not know exactly what happened beneath the crust to cause these changes, but the features created on the surface by tectonic action underneath the crust are well known.
At the same time as the Sevier mountains ceased to rise, a similar range, facing the opposite direction, began to move upward. Earth's upper crust beneath the Rocky mountain states was shoved westward in the Laramide orogeny, lifting the Rocky mountains for the first time. These first modern Rocky Mountains drained the continent's last great shallow sea of inland North America as they rose. Huge mountains now stood in places where seas had rolled over Colorado, Wyoming, Utah, Idaho, Montana, and Alberta. In Mexico, the Laramide orogeny raised the Sierra Madre Occidental, and formed the mineral deposits that enrich Sonora, Chihuahua, Durango, and Zacatecas. In Colorado, Wyoming, and neighboring states, the Rocky Mountains began to erode away, and by 55 million years ago, the first Rockies had disappeared from the surface—the mountains' roots were buried in sediment from the eroded mountain tops. More recent uplift again exposed the Rockies, and ice age glaciers sculpted their tops into today's sharp peaks.
Twenty-five million years ago, after a quiet interlude, North America's western continental arc awoke, and its abundant volcanos again added new rock to the continent from British Columbia to Texas and down the mountainous spine of Mexico. The only area in the Southwest in which volcanos were uncommon was the Colorado Plateau, whose immunity to the tectonic forces around it is still a mystery. Around the borders of the Colorado Plateau's remarkably thick crust, one volcanic catastrophe after another covered the land. In this time the San Juan mountains were formed in Colorado. The Rocky Mountains began to slide westward and rose again on the thrust faults beneath them.
Ten million years ago, the Great Basin area of the United States was much shorter when measured east to west than it is today. It was then a mountainous highland. Some geologists propose that Nevada was an alpine plateau like Tibet is today—perhaps more than 10,000 ft (3,048 m) high. Starting then and continuing for five million years, this area began to be pulled apart. Long faults opened in the crust, and mountain-sized wedges slowly fell between ridges that were still standing on the unbroken basement rock miles below. Sediment from the erosion of these new ridges filled the valleys, enabling the valleys to become reservoirs of underground water, or aquifers. The low parts got so low that the area is indeed a basin; water does not flow out of it. Some geologists believe that the Basin and Range province stretches around the Colorado Plateau, into Texas, and extends down the Sierra Madre Occidental as far south as Oaxaca.
Another kind of pulling-apart of the continent happened in New Mexico's Rio Grande rift. As at the Keewenaw rift a billion years before, tectonic forces from beneath Earth's crust began pulling the surface apart just as east Africa is being pulled apart today. The broad rift's mountainous walls eroded, and the sediment from that erosion piled up in the ever-widening valley. A new ocean was about to be formed in the southwest. Lava poured from fissures in the crust near Taos, New Mexico, filling the valley floor. Also like the Keewenaw rift, the Rio Grande rift stopped growing after a few million years, as the tectonic processes ceased pulling the continent apart. The modern Rio Grande was born as a consequence of this rift, and still runs through the rift valley.
A cataclysmic volcanic event happened in Oregon and Washington 17 million years ago. For an unknown reason, perhaps a disturbance deep in Earth's mantle, or a meteor impact, lava began pouring out of cracks in Earth. So much lava poured onto the surface at once that it ran from southeastern Oregon down the Columbia river valley to the Pacific Ocean. Huge cracks in the ground called fissures flooded broad areas with basalt lava over about 500,000 years. This flood of basalt is called the Columbia river plateau. A hot spot , or an upwelling of molten rock from Earth's mantle, appears to have caused the Columbia River plateau. As the North American plate moved westward between then and now, the hot spot stayed in one place, scorching holes in Earth's crust under Idaho and erupting the lava that makes the Snake River Plain a fertile farmland. This hot spot is assumed to be the heat source that powers the geysers of Yellowstone National Park.
Arctic region
In the early Jurassic period, 200 million years ago, the northernmost edge of North America tore away from the continent and began rotating counterclockwise. This part of the continent came to rest to the northwest of North America, forming the original piece of Alaska-its northernmost mountains, the Brooks Range. In the late Cretaceous period, the farthest part of this landmass from North America struck the edge of Siberia, and became the Chukotsk Peninsula. The remaining landmass of Alaska joined North America bit by bit, in the form of exotic terrains. The Aleutians, a classic island arc, formed in the Tertiary period. The about 40 active volcanos of the Aleutians have erupted numerous times in the twentieth century, including several eruptions in the last decade from Mt. Augustine, Pavlov, Shishaldin, and Mt. Redoubt.
The Ice Age in North America
For reasons that are not yet fully understood, Earth periodically enters a time of planet-wide cooling. Large areas of the land and seas are covered in ice sheets thousands of feet thick, that remain unmelted for thousands or hundreds of thousands of years. Today, only Greenland and Antarctica lie beneath continent-sized glaciers. But in the very recent geologic past, North America's northern regions, including the entire landmass of Canada, were ground and polished by an oceanic amount of water frozen into a single mass of ice. This ice began to accumulate as the planet'sweather cooled, and began to stay frozen all year round. As it built up higher and higher, it began to move out from the piled-high center, flowing while still solid.
Vast amounts of Canadian soil and rock, called glacial till, rode on the ice sheets as they moved, or surfed slowly before the front of the ice wall. Some of the richest farmland in the United States midwest and northeast arrived in its present location in this way-as well as boulders that must be removed from fields before plowing. In the unusual geographic conditions following the retreat of the ice sheets, barren soil lay on the landscape, no longer held down by the glacier. Windstorms moved tremendous amounts of this soil far from where the glacier left it, to settle out of the sky as a layer of fertile soil, called loess in German and English. Loess soils settled in the Mississippi and Missouri valleys, and also Washington, Oregon, Oklahoma, and Texas.
This continental glaciation happened seven times over the last 2.2 million years. Warm intervals, some of them hundreds of thousands of years long, stretched between these planetary deep-freezes. Geologists do not agree whether the ice will return or not. Even if the present day is in a warm period between glaciations, tens or hundreds of thousands of years may elapse before the next advance of the ice sheets.
Modern geologic events in North America
California lies between two different kinds of plate boundaries. To the south, the crust under California is growing; to the north it is shrinking. The part of California that sits on the Pacific plate between these two forces is moved northward in sudden increments of a few feet which are felt as earthquakes. A few feet at a time, in earthquakes that happen every few decades, the part of California west of the San Andreas Fault will move northward along the coast.
Active faults also exist elsewhere in the United States, in the midwest and in South Carolina. The last sizeable earthquakes in these regions occurred more than a hundred years ago, and geologists assume that earthquakes will probably occur within the next hundred years. The Pacific Northwest and Alaska, sitting atop active tectonic environments, will certainly be shaken by earthquakes for millions of years to come. The Great Basin, the western Rocky Mountains, and the United States northeast are all considered tectonically active enough for earthquakes to be considered possible.
North America's volcanic mountain ranges, the Cascades, and the relatively recent Mexican volcanic belt, have erupted often in the recent geologic past. These mountains will certainly continue to erupt in the near geologic future.
Resources
books
Colbert, E., ed. Our Continent. Washington, DC: The National Geographic Society, 1976.
Hancock, P. L., and B. J. Skinner, eds. The Oxford Companion to the Earth. Oxford: Oxford University Press, 2000.
Harris, D., and E. Kiver. The Geologic Story of the NationalParks and Monuments. 4th ed. New York: John Wiley and Sons, 1985.
Menzies, Gavin. 1421: The Year China Discovered America. New York: William Morrow & Co., 2003.
Stetter, J., ed. Geology of the Great Basin. University of Nevada Press, 1986.
Sullivan, W. Landprints. New York: The New York Times Book Co. Inc., 1984.
periodicals
Bokelmann, G.H.R. "Which Forces Drive North America?" Geology 30, no. 11 (2002): 1027-1030.
Clinton Crowley
KEY TERMS
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
- Archean eon
—The interval of geologic time from 3.8 billion years ago to 2.5 billion years ago.
- Canadian shield
—The oldest part of North America, made of rocks formed between 3.8 and 2.5 billion years ago, that underlies much of northern and eastern Canada.
- Collisional mountain belt
—A mountain range, like the Appalachians, caused by one continent running into another continent.
- Continental arc
—A volcanic mountain range, like the Cascades, that forms on the tectonically active edge of a continent, over a subduction zone.
- Craton
—A piece of a continent that has remained intact since Earth's earliest history, and which functions as a foundation, or basement, for more recent pieces of a continent.
- Fault block mountains
—A mountain range, like the Front Range of the Rocky Mountains, caused by horizontal forces that squeeze a continent, fracturing its crust and pushing blocks of crust up to form mountains. Also, a mountain range, like the Shoshone Range of Nevada, caused by horizontal forces that stretch a continent, fracturing the crust and causing some blocks of crust to sink down, leaving other blocks standing at high elevations above the valleys.
- Glacial till
—Rocks, soil and other sediments transported by a glacier then deposited along its line of farthest advance.
- Island arc
—A volcanic mountain range, like the Aleutians, built on a tectonically active plate boundary in the sea, which appears as islands.
- Phanerozoic eon
—The interval of geologic time beginning 570 million years ago, the rocks of which contain an abundant record of fossilized life.
- Plate tectonics
—The interactions of the plates of Earth's crust, which float on top of Earth's mantle, and whose movements through geologic time have caused the major features of the continents.
- Precambrian era
—The combined Archean and Proterozoic eons, the first four billion years of Earth's history.
- Proterozoic eon
—The interval of geologic time beginning 2.5 billion years ago and ending 570 million years ago.
North America
NORTH AMERICA
English interest in North America began soon after Christopher Columbus's first discoveries when John Cabot (c. 1450–c. 1499), a Venetian sailor, was commissioned by Henry VII in 1497 to find a northwest route to the East. The voyage proved ineffectual and for the next seventy years England remained on the sidelines of westward exploration, largely because of political and religious divisions at home. Interest did not really revive until the fourth quarter of the sixteenth century, when the success of the Spanish and Portuguese empires demonstrated the economic and strategic value of having colonies. Since the North American continent remained largely free of European settlement, the new advocates of colonization, notably English geographer Richard Hakluyt (c. 1552–1616), argued that the settling of these territories would allow the production of valuable tropical products like sugar, silk, olives, spices, hardwoods, and vines. These items had to be purchased from foreign rivals, resulting in a trade deficit and loss of bullion. In addition, Hakluyt argued, the possession of colonies would increase the maritime power of England, making her a force to be reckoned with among the nation-states of Europe.
FIRST SETTLEMENTS
Since the crown lacked the resources for such ventures, it was initially left to individuals like Sir Walter Raleigh (1554–1618) to fulfill these dreams. Unfortunately, Raleigh's attempt to settle Roanoke Island along the North Carolina coast between 1585 and 1587 proved unsuccessful, mainly because he lacked the necessary resources. However, the development of joint stock companies promised to solve this problem by allowing funds to be pooled on a large scale. Not that these new entities found colonization easy, as the attempts of the Plymouth and Virginia companies proved. The former failed to establish its colony of Sagadahoc in 1607 on the coast of present-day Maine, while the latter had to struggle for twenty years to ensure the success of Jamestown, England's first permanent settlement on the mainland of North America. In reality, too little was known about the Chesapeake region when the first settlers arrived in 1607, and the project came close to collapse several times.
Despite these difficulties, other schemes duly followed, though the impulse was increasingly religious rather than commercial. England, like much of Europe, was experiencing religious turmoil, and America seemingly offered a refuge to those suffering persecution at home. Accordingly, in 1620 a group of Pilgrims led by the Separatist church leader William Brewster (1567–1644) set sail in the May-flower to establish the Plymouth colony, while from 1629 to 1640 twenty thousand Puritans left England to establish the colonies of Massachusetts Bay in 1630, Rhode Island and Connecticut in 1636, and New Haven in 1637. Nor were Protestants alone in this exodus. In 1632 George Calvert, the first baron Baltimore (c. 1580–1632), obtained a charter from Charles I for a colony allowing religious toleration for Roman Catholics, which he called Maryland in honor of the queen.
Baltimore's charter differed from those granted to the Virginia and Massachusetts Bay Companies in that authority was vested in a single proprietor. Otherwise, both types of charter gave the grantees extensive powers, including authority to make local ordinances for the better government of their territories, providing such ordinances were consistent with the laws of England. The crown also retained the right to a fifth of all precious minerals found in their settlements. However, in 1618 the Virginia Company decided to establish a local assembly as a more effective way of involving the inhabitants in the success of the venture. This pattern was soon adopted in other colonies, notably Massachusetts, not least because that colony's charter, based on the joint stock model, required its officers to be elected annually by the shareholders. Even the autocratic second baron Baltimore (Cecilius Calvert, 1605–1675) found it politic to give his settlers an assembly as a means of attracting support. The qualifications for voting varied. In Maryland and Virginia it was generally restricted to freeholders (meaning males with property), but in Massachusetts the Puritan leadership quickly substituted church membership as the criterion for participation in the affairs of the colony.
SECOND WAVE
Although English settlement of North America was interrupted at the outbreak of the English Civil War in 1641, the restoration of Charles II in 1660 allowed a second wave of colonization, beginning in 1664 with the conquest of the Dutch colony of New Netherland in present-day New York. It was seized partly for economic reasons, to secure entry to the northern fur trade; partly to create a patrimony for the duke of York, the king's younger brother; and partly as a strategy: to close a dangerous gap between the New England and Chesapeake Bay settlements. But even before the seizure of the Dutch colony, another scheme was afoot to settle the area south of Virginia. Here, too, the founding of the Carolinas was partly commercial, to tap the possibilities of exotic cash crops in a subtropical climate; partly strategic, to provide a buffer between Virginia and the Spanish in Florida; and partly an attempt to endow the eight proprietors sponsoring the scheme with the privileges of semifeudal palatine princes. Not that religious considerations were entirely forgotten after 1660. In 1682 William Penn (1644–1718) secured a proprietary charter to provide a haven for the Society of Friends, or Quakers, as they were more commonly known. But as was the case with the Carolinas, the colonization of Pennsylvania had a strong economic rationale: to exploit the rich potential of the Delaware River area. It was also intended to enhance the dynastic aspirations of the proprietary family.
For much of the seventeenth century, England's control of its burgeoning empire was necessarily weak, given the distance of the colonies from England and the confused state of the mother country. Compounding the problems was the fact that there was no common system of government in the various settlements. Virginia, the oldest colony, had a governor appointed by the crown, a council appointed by the governor, and an elective assembly representing the propertied classes, and this was to be the model most favored by the crown after 1689 as its best means of maintaining control. However, the New England colonies at this time were largely self-governing commonwealths, while the Carolinas, Pennsylvania, and New York were all under proprietary control.
Even so, the period was not without some tightening of the imperial reins. In 1651 the first Navigation Act was passed to protect England's growing trade with its empire in the West Indies and mainland North America, and this was followed by several similar such laws in the next twenty-five years. Then in 1680 New Hampshire was separated from Massachusetts and made into a royal colony on the Virginia model. More grandiosely, in the mid-1680s James II attempted to merge the northern colonies into one entity, the Dominion of New England, to allow a more effective defense and use of scarce resources. That scheme proved too unpopular and was discarded during England's 1689 Glorious Revolution, which limited sovereign power and ended the concept of the divine right of kings. Nevertheless, some changes were effected. Massachusetts now had to accept a charter on the Virginia model, albeit with the concession that the lower house still helped nominate the governor's council, as had been required under the old charter of 1629. The crown also had a further success in East and West Jersey in the early 1700s, when the proprietors decided to surrender their governmental rights over the territory. Finally, in the 1720s the crown, with Parliament's help, engineered a similar outcome in the Carolinas, after the proprietary government failed to defend those colonies successfully from Spanish and Indian attacks. However, Pennsylvania and Maryland remained proprietary colonies while Connecticut and Rhode Island anomalously retained their corporate charters, which had originally been granted by Parliament during the English Civil War.
DENOMINATIONS AND DIVERSITY
During the seventeenth century the colonies' population was overwhelmingly English in origin, with only a few pockets of non-English stock, most importantly in Pennsylvania, where Penn settled a group of lower Rhineland Pietists at Germantown in 1686, and in New York, where the Dutch remained a distinct group. But already there was a growing number of African slaves, especially in the South, and this trend toward a more diverse population continued during the eighteenth century, aided by the absence of any restrictive immigration laws. In 1707 the Act of Union between England and Scotland officially opened the way to Scottish emigration, while the cessation of the War of the Spanish Succession in Europe in 1714 permitted further German emigration from the Palatinate and Rhineland areas. In addition, large numbers of Scots Irish began to arrive after 1717 following the termination of their leases in Ireland. All these European peoples came seeking a better life where land was plentiful and religious discrimination was minimal. Prior to 1715 the New England region had been uniformly Congregational, the South largely Anglican, with the Dutch Reformed and Society of Friends preeminent in the Hudson and Delaware Valleys. Now, outside New England, there were Presbyterians, Baptists, Moravians, and German Reformed and Lutheran churches, all adding to the multireligious and multicultural nature of the colonies and establishing a trend that has continued ever since.
ECONOMY
The economy of Britain's North American colonies was similarly varied, primarily as the result of differences in the climate and soil. The relatively temperate climate of the New England and Mid-Atlantic colonies allowed their inhabitants to practice European-style farming in cereals, root crops, and animal husbandry. And as in Europe, most northern farms relied on their families to meet their labor requirements. In the South, on the other hand, the longer and warmer growing season permitted the cultivation of more exotic cash crops like tobacco in the Chesapeake Bay area and Albemarle Sound region of North Carolina and rice in the lower part ofNorth Carolina, South Carolina, and Georgia (after 1733). Since these crops were labor-intensive, their production presented a problem, not least because most Native Americans refused to acculturate to European-style production methods and were in any case too few in number. Initially the labor problem was solved in the Chesapeake region by the system of indentured servitude. However, indentured servants served for only a few years, after which they were free to compete with their former masters. As a result, southern planters began increasingly to use African slave labor, especially when the cost of doing so dropped toward the end of the seventeenth century. The early settlers in South Carolina, in any case, deployed African slaves, being familiar with their use from their previous experience as sugar planters in Barbados.
Another difference between the northern and southern economies was the North's greater diversification. The northern colonies had no high-value commodities to export other than those obtained through the extractive pursuits of fishing and lumbering. Consequently, they had to be more self-sufficient, which led to the development of craft industries and the beginnings of manufacturing in pottery and iron ware. Shipbuilding was also widespread, and commerce generally flourished, which in turn stimulated urban growth. By the mid-eighteenth century, Boston, New York, and Philadelphia all had populations of more than ten thousand, with Philadelphia ranking as the second-largest city in the British Empire. The South, by contrast, had only one town of any consequence: Charleston in South Carolina.
By 1750 the thirteen British mainland colonies had a population around 1.5 million (including 250,000 persons of African descent) who provided a third of all British trade.
THE CAUSES OF REVOLT
Thus, although the British had been late to enter the race for overseas colonies (compared to Spain and Portugal), their settlements now constituted perhaps the most valuable possessions of any European nation. It was this realization that led Britain to attempt a strengthening of the imperial ties after the Seven Years' War (1756–1763). Among the more important initiatives were the Proclamation of 1763, which attempted to limit westward expansion; the Sugar Act of 1764, to raise revenue and strengthen the laws of trade; and the Stamp Act of 1765, to raise additional revenue for the running of the empire. But far from strengthening imperial control, these measures antagonized the colonial population and led to disputes over the sovereignty of Parliament and the rights of the colonists, especially on matters of taxation. It was failure to resolve these issues, among others, that led to the Declaration of Independence in 1776 and creation of the United States, signaling an end to the first British Empire.
See also American Independence, War of (1775–1783) ; Boston ; Charleston ; Colonialism ; Commerce and Markets ; Divine Right Kingship ; Dutch Colonies: The Americas ; Exploration ; Navigation Acts ; New York ; Philadelphia ; Puritanism ; Quakers ; Slavery and the Slave Trade ; Taxation ; Triangular Trade Pattern.
BIBLIOGRAPHY
Andrews, Charles M. The Colonial Period of American History. 4 vols. New Haven, 1934–1938. Reprint, vols. 1–3, 2001.
Bailyn, Bernard. The Peopling of British North America: An Introduction. New York, 1986.
Bonwick, Colin. The American Revolution. Charlottesville, Va., 1991.
Butler, Jon. Becoming America: The Revolution before 1776. Cambridge, Mass., 2000.
Egnal, Marc. New World Economies: The Growth of the Thirteen Colonies and Early Canada. New York, 1998.
Kammen, Michael. Deputyes & Libertyes: The Origins of Representative Government in Colonial America. New York, 1969.
Meinig, Donald William. The Shaping of America: A Geographical Perspective on 500 Years of History. 3 vols. New Haven, 1986–1993. Volume one is Atlantic America, 1492–1800.
Middleton, Richard. Colonial America: A History, 1565– 1776. 3rd ed. Oxford, 2002.
Nash, Gary B. Red, White, and Black: The Peoples of Early America. Englewood Cliffs, N.J., 1974.
Vickers, Daniel. A Companion to Colonial America. Oxford, 2003.
Wood, Betty. The Origins of American Slavery: Freedom and Bondage in the English Colonies. New York, 1997.
Richard Middleton
North America
North America
The landmass occupied by the present-day countries of Canada, the United States, and the Republic of Mexico make up North America. Greenland (Kalaallit Nunaat), an island landmass to the northeast of Canada, is also included in North America, for it has been attached to Canada for almost two billion years.
Plate tectonics is the main force of nature responsible for the geologic history of North America. Over time, the plates have come together to form the continents, including North America. Other processes, such as sedimentation and erosion , modify the shape of the land that has been forged by plate tectonics.
North American geologic history includes several types of mountain ranges as a result of plate tectonics. When the edge of a plate of Earth's crust runs over another plate, forcing the lower plate deep into Earth's elastic interior, a long, curved mountain chain of volcanoes usually forms on the forward-moving edge of the upper plate. When this border between two plates forms in the middle of the ocean, the volcanic mountains form a string of islands, or archipelago, such as the Antilles and the Aleutians. This phenomenon is called an island arc.
When the upper plate is carrying a continent on its forward edge, a mountain chain, like the Cascades, forms right on the forward edge. This edge, heavily populated with volcanoes, is called a continental arc. The volcanic mountains on the plate border described above can run into a continent, shatter the collision area and stack up the pieces into a mountain range. This is how the Appalachians were formed.
When a continent-sized "layer cake" of rock is pushed, the upper layers move more readily than the lower layers. The layers separate from each other, and the upper few miles of rock move on ahead, floating on fluid pressure between the upper and lower sections of the crust like a fully loaded tractor trailer gliding effortlessly along an icy road. The flat surface where moving layers of crust slide along the top of the layers beneath it is called a thrust fault, and the mountains that are heaved up where the thrust fault reaches the surface are one kind of fault block mountains. The mountains of Glacier National Park slid along the Lewis thrust fault over younger rocks, and out onto the Great Plains.
Mountain ranges start being torn down by physical and chemical forces while they are still rising. North America has been criss-crossed by one immense range of mountains after another throughout its almost four-billion-year history.
A range of mountains may persist for hundreds of millions of years, like the Appalachians. On repeated occasions, the warped, folded rocks of the Appalachians were brought up out of the continent's basement and raised thousands of feet by tectonic forces. If mountains are not continuously uplifted, they are worn down by erosion in a few million years. In North America's geologic past, eroded particles from its mountains were carried by streams and dumped into the continent's inland seas , some of which were as large as the present-day Mediterranean. Those rivers and seas are gone from the continent, but the sediments that filled them remain, like dirt in a bathtub when the water is drained. The roots of all the mountain ranges that have ever stood in North America all still exist, and much of the sand and clay into which the mountains were transformed still exists also, as rock or soil formations.
Various parts of North America were formed all over the world, at various times over four billion years, and were brought together and assembled into one continent by the endless process of plate tectonics. What is now called North America began to form in the first two and one-half billion years of Earth's history, a period of time called the Archean Eon.
Some geologists speculate that the earth that created the oldest parts of North America barely resembled the middle-aged planet on which we live. The planet of four billion years ago had cooled enough to have a solid crust, and oceans of liquid water. But the crust may have included hundreds of small tectonic plates, moving perhaps 10 times faster than plates move today. These small plates, carrying what are now the most ancient rocks, scudded across the oceans of a frantic crazy-quilt planet. Active volcanoes and rifts played a role in rock formation on the Archean Earth. The oldest regions in North America were formed in this hyperactive world. These regions are in Greenland, Labrador, Minnesota, and Wyoming.
In the late Archean Eon, the plates of Earth's crust may have moved at a relatively high speed. Evidence of these wild times can be found in the ancient core of North America. The scars of tectonic events appear as rock outcrops throughout the part of northern North America called the Canadian Shield. One example of this kind of scar, a greenstone belt , may be the mangled remains of ancient island arcs or rifts within continents. Gold and chromium are found in the greenstone belts, and deposits of copper, zinc, and nickel. Formations of iron ore also began to form in the Archean Eon, and fossils of microscopic cyanobacteria-the first life on Earth—are found imbedded in them.
North America's little Archean continents slammed together in a series of mountain-building collisions. The core of the modern continent was formed 1,850 million years ago when five of these collisions occurred at once around northeastern Canada. This unified piece of ancient continental crust, called a craton , lies exposed at the surface in the Canadian Shield, and forms a solid foundation under much of the rest of the continent.
In the two billion years of the Proterozoic Eon (2,500–570 million years ago), North America's geologic setting became more like the world as we know it. The cores of the modern continents were assembled, and the first collections of continents, or supercontinents , appeared. Life, however, was limited to bacteria and algae, and unbreatheable gases filled the atmosphere. Rampant erosion filled the rivers with mud and sand, because no land plants protected Earth's barren surface from the action of rain, wind , heat, and cold.
Rich accumulations of both rare and common metallic elements make Proterozoic rocks a significant source of mineral wealth for North America, as on other continents. Chromium, nickel, copper, tin, titanium, vanadium, and platinum ores are found together in the onion-like layers of crystallized igneous rocks called layered intrusions. Greenstone belts are mined for copper, lead , and zinc, each of which is mixed with sulfur to form a sulfide mineral. Sulfide minerals of lead and zinc are found in limestones formed in shallow seas, while mines in the ancient continental river and delta sediments uncover buried vanadium, copper, and uranium ores.
During the middle to late Proterozoic Eon, continental collisions attached new pieces of continental crust to North America's southern, eastern, and western borders. Between 30% and 40% of North America joined the continent in the Proterozoic. The crust underlying the continental United States east of Nevada joined the craton, as well as the crust underlying the Sierra Madre Occidental of Sonora, Chihuahua, and Durango in Mexico. The Mazatzal Mountains, whose root outcrop is in the Grand Canyon's inner gorge, rose in these mountain-building times in southern and central North America.
North America experienced the sea washing over its boundaries many times during the three-billion-plus years of its Archean and Proterozoic history. Life had flourished in the shallow tidewater. Algae, a long-term resident of North America, was joined later by worms and other soft-bodied animals. Little is known of early soft-bodied organisms, because they left no skeletons to become fossils. Only a handful of good fossils remain from the entire world's immense Precambrian rock record.
Then, about 570 million years ago, several unrelated lineages of shell-bearing sea animals appeared. This was the beginning of the Phanerozoic Eon of earth history, which has lasted from 570 million years ago to the present day. Vast seas covered much of North America in the early Phanerozoic, their shorelines changing from one million-year interval to the next. The seas teemed with creatures whose bones and shells we have come to know in the fossil record . These oceanic events are memorialized in the layers of stone each sea left behind, lying flat in the continent's heartland, and folded and broken in the cordilleras. Geologists have surveyed the stacked sheets of stone left by ancient North American seas and have made maps of the deposits of each continental sea. The stacked layers are divided into sequences, each named for the sea that laid it down. Each sequence consisted of a slow and complex flooding of the continent. Sea level mountain uplift, the growth of deltas, and other factors continually changed the shape of the continental sea.
The eastern coast of North America was once part of an ancient "Ring of Fire" surrounding an ocean that has disappeared forever from Earth. From Greenland to Georgia, and through the Gulf Coast states into Mexico, the collision of continents raised mountains comparable to the Himalayas and Alps of today. Several ranges were raised up on the eastern border of North America between 480 and 230 million years ago.
Another collision about 450 million years ago created the Acadian mountain range, whose roots are exposed today in Newfoundland. These mountains began to be torn down by rain and wind, and by the time they had worn down to nothing, more than 63,000 cubic miles of sediment made from them had been dumped into the shallow continental sea between New York and Virginia—about the same amount of rock as the Sierra Nevadas of today. The bones of amphibians, the first land animals, are found in the rocks laid down by the streams of East Greenland.
The sleepless crust under North America's Pennsylvanian-age borders tossed and turned in complex ways. Three hundred million years ago, North America sat on the equator, its vast inland sea surrounded by rain forests whose fossilized remains are the coal deposits of the eastern United States. Small mountain ranges rose out of the sea that covered the center of the continent in Colorado, Oklahoma, and Texas. The Ouachitas stood in the Gulf Coast states, the last great mountain range to stand there. In the eastern United States, the Allegheny Mountain Range stood where the Acadian and Taconic Ranges had stood before.
The Ouachitas welded South America to the Gulf coast, at roughly the same time as the Alleghenies welded the East coast of North America to West Africa . The Ouachitas and Alleghenies stretched, unbroken, all the way around the eastern and southern coasts of North America. This joining of the world's continents formed Pangaea, the most recent supercontinent in geologic history. Pangaea's 150 million year history ended with the birth of the Atlantic Ocean and the separation of North and South America. As South America and Africa tore away from North America, Florida was left behind, attached to the intersection of the Allegheny and Ouachita Mountains. Another legacy of this cracking of Earth's crust is the New Madrid Fault, which runs through the North American Plate under the Mississippi Valley.
Around 340 million years ago, an offshore island arc, called the Antler Arc, struck the shores about where Nevada and Idaho now are (then the westernmost part of the continent), extending the shoreline of North America a hundred miles westward.
By 245 million years ago, the beginning of the age of dinosaurs, another island arc had run into the American West. The Golconda Arc added a Sumatra-sized piece of land to North America, and the continent bulged out to present-day northern California.
After the Golconda Arc piled onto the West Coast of that time, the crust broke beneath the continent's border, and the ocean's plate ran under North America's west coast. A continental arc was born around 230 million years ago in western North America, and its volcanoes have been erupting frequently from the dawn of the age of dinosaurs (the Mesozoic Era ) until today.
Several more island arcs struck western North America since the middle Jurassic Period . The granite mountains of the Sierra Nevada are the roots of one of these island arcs. Landmasses created on the Pacific Plate have been scraped from it. This mechanism is the origin of the West Coast's ranges, the Cascades, and much of British Columbia and Alaska's southern coast.
A range of fault block mountains rose far inland as the continent was squeezed from west to east. The Sevier Mountains stood west of the Cretaceous Period's interior seaway, in what is now Montana, Idaho, Nevada, and Utah. The dinosaurs of that time (80–130 million years ago) left their tracks and remains in the mud and sand worn off these mountains.
In the same manner as large island chains were carried to North America on moving plates of oceanic crust, small pieces of land came to the coasts in this way as well. Numerous "exotic terrains," impacting on the western coasts during the Mesozoic and Cenozoic Eras, added large areas now covered by British Columbia, Washington, Oregon, California, and Mexico. These little rafts of continental crust were formed far from their present location, for the fossils in them are of creatures that lived halfway around the world—but never in North America. A sizeable piece of continental crust—southern Mexico as far south as the Isthmus of Tehuantepec—joined northern Mexico between 180–140 million years ago.
Starting 80 million years ago, new forces began to act on the inland west. Geologists do not know exactly what happened beneath the crust to cause these changes, but the features created on the surface by tectonic action underneath the crust are well known.
At the same time as the Sevier Mountains ceased to rise, a similar range, facing the opposite direction, began to move upward. Earth's upper crust beneath the Rocky Mountain states was shoved westward as the Laramides were forming, lifting the Rocky Mountains for the first time. These first modern Rocky Mountains drained the continent's last great shallow sea of inland North America as they rose. Huge mountains now stood in places where seas had rolled over Colorado, Wyoming, Utah, Idaho, Montana, and Alberta. In Mexico, the Laramides raised the Sierra Madre Occidental, and formed the mineral deposits that enrich Sonora, Chihuahua, Durango, and Zacatecas. In Colorado, Wyoming, and neighboring states, the Rocky Mountains began to erode away, and by 55 million years ago, the first Rockies had disappeared from the surface—the mountains' roots were buried in sediment from the eroded mountaintops. More recent uplift again exposed the Rockies, and Ice Age glaciers sculpted their tops into today's sharp peaks.
Twenty-five million years ago, after a quiet interlude, North America's western continental arc awoke, and its abundant volcanoes again added new rock to the continent from British Columbia to Texas and down the mountainous spine of Mexico. The only area in the Southwest in which volcanoes were uncommon was the Colorado Plateau, whose immunity to the tectonic forces around it is still a mystery. Around the borders of the Colorado Plateau's remarkably thick crust, one volcanic catastrophe after another covered the land. In this time, the San Juan Mountains were formed in Colorado. The Rocky Mountains began to slide westward and rose again on the thrust faults beneath them.
Ten million years ago, the Great Basin area of the United States was much shorter when measured east to west than it is today. It was then a mountainous highland. Some geologists propose that Nevada was an alpine plateau like Tibet is today—perhaps more than 10,000 ft (3,048 m) high. Starting then and continuing for five million years, this area began to be pulled apart. Long faults opened in the crust, and mountain-sized wedges slowly fell between ridges that were still standing on the unbroken basement rock miles below. Sediment from the erosion of these new ridges filled the valleys, enabling the valleys to become reservoirs of underground water, or aquifers. The low parts got so low that the area is indeed a basin; water does not flow out of it. Some geologists believe that the Basin and Range province stretches around the Colorado Plateau, into Texas, and extends down the Sierra Madre Occidental as far south as Oaxaca.
Another kind of pulling-apart of the continent happened in New Mexico's Rio Grande Rift. As at the Keewenaw Rift a billion years before, tectonic forces from beneath Earth's crust began pulling the surface apart just as east Africa is being pulled apart today. The broad rift's mountainous walls eroded, and the sediment from that erosion piled up in the ever-widening valley. A new ocean was about to be formed in the southwest. Lava poured from fissures in the crust near Taos, New Mexico, filling the valley floor. Also like the Keewenaw Rift, the Rio Grande Rift stopped growing after a few million years, as the tectonic processes ceased pulling the continent apart. The modern Rio Grande was born as a consequence of this rift, and still runs through the rift valley.
A cataclysmic volcanic event happened in Oregon and Washington 17 million years ago. For an unknown reason, perhaps a disturbance deep in Earth's mantle, or a meteor impact, lava began pouring out of cracks in Earth. So much lava poured onto the surface at once that it ran from southeastern Oregon down the Columbia River valley to the Pacific Ocean. Huge cracks in the ground called fissures flooded broad areas with basalt lava over about 500,000 years. This flood of basalt is called the Columbia River Plateau. A hot spot, or an upwelling of molten rock from Earth's mantle, appears to have caused the Columbia River Plateau. As the North American Plate moved westward between then and now, the hot spot stayed in one place, scorching holes in Earth's crust under Idaho and erupting the lava that makes the Snake River Plain a fertile farmland. This hot spot is assumed to be the heat source that powers the geysers of Yellowstone National Park.
In the early Jurassic Period, 200 million years ago, the northernmost edge of North America tore away from the continent and began rotating counterclockwise. This part of the continent came to rest to the northwest of North America, forming the original piece of Alaska—its northernmost mountains, the Brooks Range. In the late Cretaceous Period , the farthest part of this landmass from North America struck the edge of Siberia, and became the Chukotsk Peninsula. The remaining landmass of Alaska joined North America bit by bit, in the form of exotic terrains. The Aleutians, a classic island arc, formed in the Tertiary Period . The about 40 active volcanoes of the Aleutians have erupted numerous times in the twentieth century, including several eruptions in the last decade from Mt. Augustine, Pavlov, Shishaldin, and Mt. Redoubt.
For reasons that are not yet fully understood, Earth periodically enters a time of planet-wide cooling. Large areas of the land and seas are covered in ice sheets thousands of feet thick, which remain unmelted for thousands or hundreds of thousands of years. Today, only Greenland and Antarctica lie beneath continent-sized glaciers. But in the very recent geologic past, North America's northern regions, including the entire landmass of Canada, were ground and polished by an oceanic amount of water frozen into a single mass of ice. This ice began to accumulate as the planet's weather cooled, and began to stay frozen all year round. As it built up higher and higher, it began to move out from the piled-high center, flowing while still solid.
Vast amounts of Canadian soil and rock, called glacial till , rode on the ice sheets as they moved, or surfed slowly before the front of the ice wall. Some of the richest farmland in the United States Midwest and northeast arrived in its present location in this way-as well as boulders that must be removed from fields before plowing. In the unusual geographic conditions following the retreat of the ice sheets, barren soil lay on the landscape, no longer held down by the glacier. Windstorms moved tremendous amounts of this soil far from where the glacier left it, to settle out of the sky as a layer of fertile soil, called loess in German and English. Loess soils settled in the Mississippi and Missouri Valleys, and also Washington, Oregon, Oklahoma, and Texas.
This continental glaciation happened seven times over the last 2.2 million years. Warm intervals, some of them hundreds of thousands of years long, stretched between these planetary deep-freezes. Geologists do not agree whether the ice will return or not. Even if the present day is in a warm period between glaciations, tens or hundreds of thousands of years may elapse before the next advance of the ice sheets.
California lies between two different kinds of plate boundaries. To the south, the crust under California is growing; to the north it is shrinking. The part of California that sits on the Pacific Plate between these two forces is moved northward in sudden increments of a few feet which are felt as earthquakes. A few feet at a time, in earthquakes that happen every few decades, the part of California west of the San Andreas Fault will move northward along the coast.
Active faults also exist elsewhere in the United States, in the Midwest and in South Carolina. The last sizeable earthquakes in these regions occurred more than a hundred years ago, and geologists assume that earthquakes will probably occur within the next hundred years. The Pacific Northwest and Alaska, sitting atop active tectonic environments, will certainly be shaken by earthquakes for millions of years to come. The Great Basin, the western Rocky Mountains, and the United States northeast are all considered tectonically active enough for earthquakes to be considered possible.
North America's volcanic mountain ranges, the Cascades, and the relatively recent Mexican Volcanic Belt, have erupted often in the recent geologic past. These mountains will certainly continue to erupt in the near geologic future.
See also Continental drift theory; Continental shelf; Earth (planet); Faults and fractures; Fossils and fossilization; Ice ages; Orogeny
North America
North America
North America, the world's third-largest continent, encompasses an area of about 9,400,000 square miles (24,346,000 square kilometers). This landmass is occupied by the present-day countries of Canada, the United States, Mexico, Guatemala, Belize, El Salvador, Honduras, Nicaragua, Costa Rica, and Panama. Also included in the North American continent are Greenland, an island landmass northeast of Canada, and the islands of the Caribbean, many of which are independent republics.
North America is bounded on the north by the Arctic Ocean, on the west by the Bering Sea and the Pacific Ocean, on the south by the South American continent, and on the east by the Gulf of Mexico and Atlantic Ocean.
The North American continent contains almost every type of land-form present on Earth: mountains, forests, plateaus, rivers, valleys, plains, deserts, and tundra. It also features every type of climatic zone found
on Earth, from polar conditions in Greenland to tropical rain forests in the countries of Central America. Much of the continent, however, is subject to a temperate climate, resulting in favorable farming and living conditions.
The highest point on the continent is Mount McKinley in Alaska, standing 20,320 feet (6,194 meters) in height. Badwater, in the south-central part of Death Valley in California, is the continent's lowest point, at 282 feet (86 meters) below sea level.
Rivers and lakes
The North American continent contains the world's greatest inland waterway system. The Mississippi River rises in northern Minnesota and flows 2,348 miles (3,778 kilometers) down the center of the United States to the Gulf of Mexico. The Missouri River, formed by the junction of three rivers in southern Montana, runs 2,466 miles (3,968 kilometers) before it joins the Mississippi just north of St. Louis, Missouri. The Ohio River, formed by the union of two rivers at Pittsburgh, Pennsylvania, flows 975 miles (1,569 kilometers) before emptying into the Mississippi at Cairo, Illinois. The Mississippi, with all of its tributaries, drains 1,234,700 square miles (3,197,900 square kilometers) from all or part of 31 states in the United States. From the provinces of Alberta and Saskatchewan in Canada, the Mississippi drains about 13,000 square miles (33,670 square kilometers).
Other chief rivers in North America include the Yukon (Alaska and Canada); Mackenzie, Nelson, and Saskatchewan (Canada); Columbia and St. Lawrence (Canada and U.S.); Colorado, Delaware, and Susquehanna (U.S.); and Rio Grande (U.S. and Mexico).
North America contains more lakes than any other continent. Dominant lakes include Great Bear, Great Slave, and Winnipeg (Canada); the Great Lakes (Canada and U.S.); Great Salt Lake (U.S.); Chapala (Mexico); and Nicaragua (Nicaragua). The Great Lakes, a chain of five lakes, are Superior, Michigan, Huron, Erie, and Ontario. Superior, northernmost and westernmost of the five, is the largest lake in North America and the largest body of freshwater in the world. Stretching 350 miles (560 kilometers) long, the lake covers about 31,820 square miles (82,410 square kilometers). It has a maximum depth of 1,302 feet (397 meters).
Geographical regions
Geologists divide the North American continent into a number of geographical regions. The five main regions are the Canadian Shield, the Appalachian System, the Coastal Plain, the Central Lowlands, and the North American Cordillera (pronounced kor-dee-YARE-ah; a complex group of mountain ranges, systems, and chains).
Canadian Shield. The Canadian Shield is a U-shaped plateau region of very old, very hard rocks. It was the first part of North America to be elevated above sea level, and became the central core around which geological forces built the continent. It is sometimes called the Laurentian Plateau. It extends north from the Great Lakes to the Arctic Ocean, covering more than half of Canada and including Greenland. Hudson Bay and Foxe Basin in Canada mark the center of the region, submerged by the weight of glaciers of the most recent ice age some 11,000 years ago. Mountains ranges ring the outer edges of this geological structure. In the United States, the Adirondack Mountains and the Superior Highlands are part of the Shield.
The southern part of the Canadian Shield is covered by rich forests, while the northern part is tundra (rolling, treeless plains). The region is rich in minerals, including cobalt, copper, gold, iron, nickel, uranium, and zinc.
Appalachian System. The Appalachian Mountains extend about 1,600 miles (2,570 kilometers) southwest from Newfoundland to Alabama. They are a geologically old mountain system. Formed over 300 million years ago, the Appalachians have eroded greatly since then. Most of the system's ridges are 1,200 to 2,400 feet (360 to 730 meters) in height. Only a few peaks rise above 6,000 feet (1,800 meters). The system's highest peak, Mount Mitchell, rises 6,684 feet (2,037 meters) above sea level.
The main ranges in the system are the White Mountains (New Hampshire), Green Mountains (Vermont), Catskill Mountains (New York), Allegheny Mountains (Pennsylvania), Great Smoky Mountains (North Carolina and Tennessee), Blue Ridge Mountains (Pennsylvania to Georgia), and the Cumberland Mountains (West Virginia to Alabama).
Much mineral wealth is found throughout the Appalachian System, including coal, iron, lead, zinc, and bauxite. Other mineral resources such as petroleum and natural gas are also prevalent.
Coastal Plain. The Coastal Plain is a belt of lowlands that extends from southern New England to Mexico's Yucatan Peninsula, flanking the Atlantic Ocean and the Gulf of Mexico. This geological area was the last part added to the North American continent. Much of the plain lies underwater along the northern Atlantic Coast, forming rich fishing banks.
The southern portion of the plain, from Florida along the Gulf shore of Louisiana and Texas into Mexico, holds large deposits of phosphate, salt, and sulfur. Extensive oil and natural gas fields also line this area.
Central Lowlands. The Central Lowlands extend down the center of the continent from the Mackenzie Valley in the Northwest Territories in Canada to the Coastal Plain in the Gulf of Mexico. These lowlands circle the Canadian Shield. Included in this extensive region are the Great Plains in the west and the lowlands of the Ohio-Great Lakes-Mississippi area in the east. The great North American rivers are contained in this region, making the surrounding soil fertile for farming. The world's richest sources of coal, oil, and natural gas are also found here.
North American Cordillera. The North American Cordillera is a complex group of geologically young mountains that extend along the western edge of the North American continent. The eastern section of the Cordillera is marked by the Rocky Mountains. They extend more than 3,000 miles (4,800 kilometers) from northwest Alaska to central New Mexico. The highest peak in the Rockies is Mount Elbert in Colorado at 14,431 feet (4,399 meters) in height. The highest peak in the Canadian Rockies is Mount Robson in eastern British Columbia, rising 12,972 feet (3,954 meters). The ridge of the Rocky Mountains is known as the Continental Divide, the "backbone" of the continent that separates the rivers draining to the Arctic and Atlantic Oceans from those draining to the Pacific Ocean.
The Rockies may be divided into three sections: northern, central, and southern. The Northern Rockies, which rise to great elevations, begin in northern Alaska and extend down into Montana. From here, the Central Rockies extend down into Colorado. A high, vast plateau separates the Central Rockies from the Southern Rockies. Known as the Wyoming Basin, it varies in elevation from 7,000 to 8,000 feet (2,100 to 2,400 meters). The Southern Rockies contain the highest peaks in the entire system—many exceed 14,000 feet (4,300 meters) in height.
West of the Rockies lies a series of plateaus and basins. These include the Yukon Plateau, the uplands in central British Columbia, the Snake River Plain, the Great Basin, and the Colorado Plateau. The Great Basin, an elevated region between the Wasatch and Sierra Nevada Mountains, includes the Great Salt Lake, the Great Salt Lake and Mojave deserts, and Death Valley.
The western edge of North America is marked by two mountain ranges: the Cascade and Coast ranges. The Cascade Range extends about 700 miles (1,130 kilometers) from British Columbia through Washington and Oregon into northeast California. Many of the range's peaks are volcanic in origin. The highest peak is Mount Rainier in Washington, standing 14,410 feet (4,390 meters) in height. North of the Cascades are the Coast Mountains, which extend about 1,000 miles (1,610 kilometers) north from British Columbia into southeast Alaska. Here they are met by the Alaska Range, which extends in a great arc through south-central Alaska. This range features the highest peaks in North America, including Mount McKinley.
South of the Cascades are the Sierra Nevada Mountains, extending about 400 miles (640 kilometers) through eastern California. The Sierras, noted along with the Cascades for their beauty, contain Mount Whitney. At 14,494 feet (4,418 meters) tall, it is the highest peak in the contiguous United States (the 48 connected states).
The Coast Ranges are a series of mountain ranges along North America's Pacific coast. They extend from southeast Alaska to Baja California. The ranges include the St. Elias Mountains (Alaska and Canada); Olympic Mountains (Washington); Coast Ranges (Oregon); Klamath Mountains, Coast Ranges, and Los Angeles Ranges (California); and the Peninsular Range (Baja California). Peaks in the entire Coast Ranges extend from 2,000 to 20,000 feet (610 to 6,100 meters) in height.
In Mexico, the chief mountain system is the Sierra Madre, composed of the Sierra Madre Occidental, the Sierra Madre Oriental, and the Sierra Madre del Sur. The Sierra Madre Occidental begins just south of the Rio Grande River and runs about 700 miles (1,130 kilometers) parallel to the Gulf of Mexico. The Occidental contains the highest peak in the Sierra Madre system, Pico de Orizaba, which rises to 18,700 feet (5,700 meters). Orizaba is also considered a part of the Cordillera de Anahuac, an east-west running belt of lofty volcanoes just south of Mexico City. In addition to Orizaba, this belt contains the volcanic peaks Popocatepetl and Ixtacihuatl. The belt connects the Occidental range to the Sierra Madre Oriental, which runs south from Arizona parallel to the Pacific coast for about 1,000 miles (1,610 kilometers). The Sierra Madre del Sur is a broken mass of uptilted mountains along the Pacific coast in southern Mexico. It forms the natural harbor of Acapulco.
North America
NORTH AMERICA
Between 1500 and 1789 the trade in North American furs and hides was profitable in western Europe for various people: furriers, hatters, and leather workers; makers of ornaments, tools, and firearms; distillers; investors and financiers; and governments of nation-states. Medieval Europe had met its own demand for furs until the supply of suitable animals was exhausted and buyers resorted to common pelts such as rabbit or expensive furs from the East. And in the rising nation-states the demand for leather, particularly by standing armies, outgrew the supply of hides from domestic markets.
From modest beginnings the North American trade developed by 1650 into a large-scale business. Native traders wanted ornaments and European clothing, metal tools for a variety of purposes, and firearms for hunting and warfare. For them trade was an exchange of gifts, and even when they demanded more European goods for their furs, their purpose was not to amass capital. Europeans therefore could buy furs relatively cheaply and sell them dearly, unless the supply of furs outran demand. Financiers invested in acquiring and shipping goods fashioned and assembled in Europe by small-scale entrepreneurs and bartered for furs with Native North Americans through individual traders, small companies, or large monopolies licensed by nationstates.
In the north France, the Netherlands, and Great Britain were most actively involved. There was a great demand for marten, muskrat, mink, otter, wolf, bear, and lynx, but the best-known fur was beaver. It was preferred for making the felt hat that, in varying styles, was immensely popular throughout the seventeenth and eighteenth centuries. In the Saint Lawrence Valley a series of French monopolies, ranging from the Company of One Hundred Associates (1628–1629 and 1632–1664) to the Company of the Indies (founded 1719), were obliged to accept at a fixed price all the marketable pelts brought to them by French traders. These traders ventured from their base at Montreal by way of the Great Lakes–Saint Lawrence drainage basin first to that of the Mississippi and subsequently across the Canadian Prairies almost to the foothills of the Rockies. The Netherlands West India Company (chartered 1621), based in the Hudson Valley, competed with them until 1660 and was succeeded by English entrepreneurs. The Hudson's Bay Company (HBC), an English monopoly founded in 1670, set up posts at the mouths of rivers flowing into Hudson and James Bays in Canada. As French traders penetrated those regions, American Indians could either travel to the HBC posts for English goods or deal with coureurs de bois ('woods runners') or voyageurs from Montreal, who brought them French goods until 1763 and British goods thereafter. Although British entrepreneurs after 1763 competed as briskly with the HBC as the French had, they were forced by the size and efficiency of the HBC to cooperate with one another until by 1787, after a series of smaller mergers, they were consolidated into the North West Company.
After 1713 the French converted the fur trade from an economic purpose into the means to a strategic end. Their chain of fortified trading posts from New Orleans to Montreal, intended to bar the western expansion of the British seaboard colonies, brought them into conflict with British traders not only from New York but also from Georgia to Pennsylvania, where entrepreneurs undertook to harvest and market the hides of deer, elk (wapiti), bison, and moose. By 1680 in Virginia and the Carolinas the deerskin trade had developed from Tidewater beginnings into lucrative enterprises featuring long packhorse trains carrying goods across the Appalachians and returning with hides. After 1720, even when Britain and France were at peace, their commercial rivalry engendered continuous, devastating warfare between their respective American Indian client nations.
Traders from New Spain (Mexico) had dealt in deerskins and buffalo hides as early as 1580 in New Mexico, appropriating trade that had been carried on among aboriginal nations and developing it into a thriving business from 1600 until at least 1780. On the Pacific Coast, in California after 1750 Spanish Franciscan friars developed a prosperous trade in hides. Russian traders, whom the Spaniards regarded as competitors, sent home from the Aleutians and Alaska enormous quantities of furs, especially sea otter.
It would nevertheless be inaccurate to believe that any European country depended on the fur trade as its economic mainstay. Notwithstanding the large volume of trade in North American furs and hides, national economies benefited much more from other fields. In the North the cod fishery thrived on a steady demand; in the South slave labor harvested such lucrative products as sugar, tobacco, coffee, chocolate, and indigo. In comparison with those commodities, furs and hides represented an insignificant fraction of the entire trade.
See also British Colonies: North America ; Commerce and Markets ; French Colonies: North America ; Spanish Colonies: Other American Colonies ; Trading Companies .
BIBLIOGRAPHY
Eccles, W. J. The Canadian Frontier, 1534–1760. Rev. ed. Albuquerque, 1983.
Rich, E. E. The Hudson's Bay Company, 1670–1870. 3 vols. Vols. 1–2. New York, 1960.
Robinson, W. Stitt. The Southern Colonial Frontier, 1607– 1763. Albuquerque, 1979.
Frederick J. Thorpe