Europe

Forces that made Europe

The Mediterranean desert

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The continent of Europe is a landmass bounded on the east by the Ural Mountains, on the south by the Mediterranean Sea, and on the north and west by the Arctic and Atlantic Oceans. Numerous islands around this landmass are considered a part of Europe. Europe is also the westernmost part of the Eurasian super-continent (several continental masses joined together).

Europe holds a unique place among the continents; much of it is “new,” in geologic terms. Unlike other continents whose structures seem simple in comparison, Europe is a collection of different kinds of geologic regions located side by side, many of which have little or nothing in common. This should be kept in mind when reading about the regions in this article, which are not areas of similar origins, but rather areas of dissimilar origin that happen to be part of the same continent.

Forces that made Europe

Plate tectonics is the main force of nature responsible for the geologic history of Europe. the earth is covered by a thin, brittle layer called the lithosphere. This term is used here interchangeably with Earth’s “crust.” Below the lithosphere is the asthenosphere, where solid rock stretches and flows. The lithosphere is composed of sections, called plates, and floats on top of the asthenosphere, because it is less dense than the asthenosphere. The motion of a tireless heat engine swirls and stirs the asthenosphere, moving the plates.

Over hundreds of millions of years, the plates have come together to form continents, including Europe. Other processes, such as sedimentation and erosion, modify the shape of the land that has been forged by plate tectonics.

Large-scale geologic elements of Europe

European geologic history, like that of all the continents, involves the formation of the following features as a result of plate tectonics:

Island arcs: When the edge of a plate of earth’s lithosphere runs over another plate, forcing the lower plate deep into the elastic interior, a long, curved chain of volcanic mountains usually erupts on the forward-moving edge of the upper plate. When this border between two plates forms in an ocean, the volcanic mountains constitute a string of islands (or archipelago ). This is called an island arc. Italy’s Appenine mountains originally formed as an island arc, then became connected into a single peninsula later.

Continental arcs: A continental arc is exactly like an island arc except that the volcanos erupt on a continent, instead of in the middle of an ocean. The chemical composition of the erupted rock is changed, because old continental rocks at the bottom of the lithosphere have melted and mixed with the magma. A clear-cut example of this kind of mountain chain no longer exists in Europe, but ancient continental arcs once played an important part in Europe’s geologic past. Sicily’s Mt. Aetna and Mt. Vesuvius on the Bay of Naples are good examples of the type of volcano that commonly make up a continental arc.

Sutures: A suture describes the place where two parts of a surgery patient’s tissue are sewed or rejoined; it also describes the belts of mountains that form when two continents are shoved into each other, over tens of millions of years, to become one. The Alps and other ranges in southern Europe stand tall because of a continental collision between Europe and Africa. The Alps and other European ranges are may be part of a fully developed suture uniting Europe and Africa. This suture would be a tall mountain range that stretches continuously from Iberia to easternmost Europe.

The collision of Africa with Europe is a continuous process that stretches tens of millions of years into the past and into the future. All the generations of humanity together have seen only a tiny increment of the continental movement in this collision. However, throughout history people have felt the collision profoundly, in earthquakes and volcanoes, with all the calamities that attend them.

Rifts: Sometimes a continent is torn in pieces by forces moving in opposite directions beneath it. On the surface, this tearing at first makes a deep valley, which experiences both volcanic and earthquake activity. Eventually the valley becomes wide and deep enough that its floor drops below sea level, and ocean water moves in. This process, called rifting, is the way ocean basins are born on earth; the valley that makes a place for the ocean is called a rift valley. Pieces of lithosphere, rifted away from Africa and elsewhere, have journeyed across Earth’s surface and joined with the edge of Europe. These pieces of lithosphere lie under southern England, Germany, France, and Greece, among other places.

Fault-block mountains: When a continent-sized “layer cake” of rock is pushed, the upper layers move more readily than the lower layers. The upper layers of rock are heavy—but easier to move than those beneath it (like a full filing cabinet is heavy—but when it’s pushed, it moves more easily than the floor beneath it). Between near surface rocks and the deeper, more ancient crustal rocks, a flat-lying fault forms, also called a “detachment” fault (de´collement in French). This horizontal crack, called a thrust fault, contains fluid (water, mostly). The same hydraulic force that makes hydraulic machines lift huge weights functions in this crack as well. The fluid is so nearly incompressible that a sizeable

piece of a continent can slide on it when pushed. The fault block floats on fluid pressure between the upper and lower sections of the lithosphere like a fully loaded tractor trailer gliding effortlessly along a rain-slicked road. The mountains that are heaved up where the thrust fault reaches the surface are one kind of fault block mountains. Both the Jura mountains and the Carpathians are fault-block mountains.

Another kind of fault-block mountain comes from stretching of Earth’s lithosphere. The lithosphere, like any other brittle material, develops cracks perpendicular to the direction of movement of the forces that are pulling it apart. In this case the force is lateral, so steep, nearly vertical faults form.

However they form, physical and chemical forces start wearing down mountain ranges while they are still rising. Europe has been crisscrossed by one immense range of mountains after another throughout its almost four-billion year history. Where did these mountains go?

If mountains are not continuously uplifted, they are worn down by erosion in a few million years. In Europe’s geologic past, eroded particles from its mountains were carried by streams and dumped into the surrounding ocean or the continent’s inland seas. Those particular rivers and seas are now gone from earth, 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 ever stood in Europe still exist, and much of the sand and clay into which the mountains were transformed still exists also, as rock or soil formations.

European geologic history

Unfortunately, the farther back in a continent’s history we attempt to explore, the less we can know about it. Only a very incomplete record of ancient geologic events is preserved for study because most ancient rocks are subsequently destroyed. For the most distant geologic time interval in Europe’s history, from 4.6 billion years ago (BYA) to 3.8 BYA, the Hadean eon, almost nothing is known and so it is not discussed here. Enough is known however about the Archean eon (3.8–2.5 BYA), the Proterozoic eon (2.5 BYA–570 million YA), and the Phanerozoic eon (570 MYA to the present) to provide a fairly detailed picture. In fact, the events of the Phanerozoic eon are known well enough to discuss them with even smaller geologic time intervals. These from largest to smallest are era, period, and epoch. The older the events, the less detail is known, so only very recent geologic epochs are discussed.

Archean rocks in Europe

Europe was not formed in one piece, or at one time. Various parts of it were formed all over the ancient world, over a period of four billion years, and were slowly brought together and assembled into one continent by the processes of plate tectonics. What is now called Europe began to form more than 3 billion years ago, during the Archean eon.

Most geologists feel that prior to and during the creation of the oldest parts of Europe, earth only superficially resembled the planet we live on today. Active volcanoes and rifts abounded. The planet had cooled enough to have a solid crust and oceans of liquid water. 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 Earth’s most ancient crustal rocks, moved across the surface of a frantic crazy-quilt planet. Whatever it truly was like, the oldest regions in Europe were formed in this remote world. These regions are in Finland, Norway (Lofoten Islands), Scotland, Russia, and Bulgaria.

Proterozoic Europe

The piece of Europe that has been in its present form for the longest time is the lithospheric crust underneath Scandinavia, the Baltic states, and parts of Russia, Belarus, and Ukraine. This region moved around on its own for a long time, and is referred to as Baltica. It is the continental core, or craton, to which other parts were attached to form Europe.

In the two billion years of the Proterozoic eon(2.5 BYA–570 MYA), the 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. Erosion clogged the rivers with mud and sand, because no land plants protected Earth’s barren surface from the action of rain, wind, heat, and cold.

During the late Proterozoic an existing supercontinent began to break up. One of the better known episodes in this supercontinent’s dismemberment was the pan-African event. This was a period when new oceans opened up and mountains rose all around Africa. Over a period of a quarter-billion years, relatively small pieces of Africa tore away and were rafted along on the asthenosphere, colliding with Baltica. These blocks include: the London Platform (southern Britain); a strip of Ireland from between counties Wicklow and Kerry; the Iberian Peninsula (Spain and Portugal); Aquitaine, Armorica, and the Massif Central (France); the Interalpine region (Switzerland and Austria); the Austrian Alps(Carnic Alps); Bohemia; Moesia (Bulgaria and Romania); and the Rhodope region (Northern Greece, Bulgaria, and European Turkey, including Istanbul).

The result is that much of northern and central Europe, on a continental scale of reference, is made of blocks of Africa stuck together in a “paste” of sedimentary rock.

Most of the mountain belts created in the Proterozoic eon have long since worn away. The roots of these mountain belts are found in northern Europe and include:

The Karelian mountain belt, forming the middle third of Norway, Sweden, and Finland, including some of Karelia, is underlain by the worn-flat roots of the Karelian mountain range. This orogenic event (from oros, Greek for mountain, and genesis, Greek for origin) happened between 2 billion and 1.7 billion years ago.

The Svecofennian mountain belt, forming most of the southern third of Norway, Sweden, and Finland, are the roots of a Proterozoic mountain belt. They lie hidden beneath recent glacier-deposited sediments, and beneath dense coniferous forests. Because these factors make examination difficult, the Svecofennian mountain-building event is not yet well understood. It is presumed that the Svecofennian mountain belt marks where Baltica’s edge was between 1.9 and 1.4 billion years ago. This mountain belt rose in a time of worldwide mountain-building, and it may have been related to the assembly of North America’s Canadian Shield.

The southernmost tips of Norway and Sweden were made in the Sveco-Norwegian/Grenville orogenic event, between 1.2 and 0.9 billion years ago. This is the mountain chain that united Baltica with North America, before most of the western and southern parts of the European landmass existed.

The Ukrainian shield: At present, geologists do not agree on when or how the Ukrainian shield was put together. Parts of it were definitely in existence before the Proterozoic eon. During the Proterozoic it was assembled, and joined Baltica.

Paleozoic Europe

The sea washed over the oldest parts of earth’s surface many times during the three-billion-plus years of Archean and Proterozoic history. Life flourished in the shallow tidewater for these 3,000 million years. Algae, one of the most ancient organisms, were 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—preserved under very rare conditions—remain from the entire world’s immense Precambrian, or combined Hadean, Archean and Proterozoic, rock records.

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 (from the Greek phaneros, meaning visible, and zoe, meaning life), which includes the time interval from 570 million years ago to the present day. The seas teemed with creatures whose bones and shells we have come to know in the fossil record. These include trilobites, brachiopods, the first fishes, and vast coral reefs. The first half of the Phanerozoic eon is called the Paleozoic Era (from the Greek palaios, meaning ancient). For Europe, the Paleozoic Era was largely a continuation of events that started in the late Proterozoic eon.

Remember, the map of the ancient earth didn’t look anything like a modern world map. As this new day of earth’s history began, Baltica sat near the South Pole. Three oceans surrounded it, and each of these oceans shrank and closed during the Paleozoic. As plate tectonics shifted island arcs and already formed blocks of crust around earth’s surface, new rock came to be a part of the forming continent of Europe; underground masses of igneous rock accumulated near active margins of Baltica; and volcanoes frequently erupted even as they do today in the Mediterranean region. Concurrent with this volcanic mountain-building, was the wearing-down of the volcanoes, and the wearing-down of mountain cores, exposed by erosion. The sediment from the erosion of these igneous rocks accumulated at the borders of the continental blocks, and often became compressed into tightly folded rock masses only a few million years after they accumulated.

Baltica faced Greenland across the Iapetus Ocean. Early in the Paleozoic Era, Europe combined again with North America to form a giant continent called Laurussia (from Laurentia, meaning the core of North America, and Russia), or the North Continent. The line along which the continents were welded together runs along the length of Norway, through central Scotland, south-central Ireland, and southern Wales. In North America this line runs down the eastern coast of Greenland. As always happens when continents collide, there an associated mountain-building event. The resulting mountains are called the Caledonides, and they stood athwart the seam that welded Baltica and Laurentia together at that time. A continental arc developed, running from Denmark southeast down the ancient coast of Baltica, which is also considered to be a part of the Caledonian orogeny. Mountains in Norway, Scotland, Wales, and Ireland bear the shapes of folds made in the Caledonian orogeny. They shed sediment as they eroded, and a great volume of sand came to rest in the British Isles (then scattered to areas throughout the region). These sandstone masses attracted the attention of early British geologists, who named them the Old Red Sandstone. They proposed that there had been a continent to the west that had entirely worn away, which they called the Old Red Sandstone continent. This continent is now known to have been the Greenland coast of Laurentia.

The Uralian Ocean lapped at Baltica’s northeastern coastline. Just before the end of the Paleozoic Era, the Ural Ocean that had washed the eastern shore of Baltica narrowed and closed forever. Two landmasses—Siberia and Kazakhstan—compressed and lifted the sediments of the Ural ocean basin into the Ural mountains. The Urals still stand today, and mark the eastern boundary of Europe within the Eurasian supercontinent.

Africa faced Baltica across the Tornquist Sea. (Two oceans that later lay between Africa and Europe, at different times, are called Tethys. Earlier versions of Tethys are called Paleo-Tethys, and later versions of it are called Neo-Tethys. No Tethys Ocean exists today.) Near the close of the Paleozoic Era (245 MYA), Laurussia united with the single southern supercontinent made up of much of the rest of the world’s continents, named Gondwana. This created the Pangea (from the Greek pan, meaning all, and Ge, meaning earth). The Central Pangean mountains arose from this mighty collision, and deformed the rocks laid down during the Paleozoic in central Europe. These mountains joined to the west with the Mauretanides of West Africa, and the Appalachians and Ouachitas of the eastern and southern United States to form a tremendous mountain range stretching along the equator for more than 4,200 miles (7,000 km). The whole mountain range is called the Hercynian Mega-suture.

Piece by piece, continental fragments tore away from Africa’s northern and western shores and were crushed into the jagged southern edge of Baltica. The same processes that transported these blocks of Europe also deformed them, often changing the crystalline fabric of the rock so much that the original igneous or sedimentary rock type can only be guessed. Between Africa and Europe, tectonic forces seem to have pushed miniature continental blocks in several directions at once—the reconstructions of this time are still unclear. The violently twisted line followed by the Variscan mountain belt anticipated the Alps and other ranges of modern Europe.

Many important rock bodies, called massifs, formed as parts of the Variscan Mountains. Giant bulbous masses of granite and other igneous rocks solidified to form England’s Cornwall; Spain and Portugal’s Cantabrian Massif; France’s Armorican Massif, Massif Central, and the Vosges; Germany’s Black Forest; and the Erzgebirge Mountains on the German-Czech border. The Balkans also contain Variscan-age massifs.

Mesozoic and Cenozoic Europe

At the opening of the Mesozoic Era, 245 MYA, a sizeable part of western and southern Europe was squeezed up into the Central Pangean mountain system that sutured Laurussia and Gondwana together. Europe was almost completely landlocked, its southern regions part of a mountain chain that stretched from Kazakhstan to the west coast of North America.

The birth of a new ocean basin, the Atlantic, signaled the end of Pangaea. The Central Pangean Mountains, after tens of millions of years, had worn down to sea level and below. A new ocean basin, not the Mediterranean, but rather the Ligurean Ocean, began to open up between Africa and Europe. This formed a seaway between the modern North Atlantic and the NeoTethys Ocean (which no longer exists). Sea water began to leave deposits where high mountains had stood, and a layer cake of sediment—laid down on the shallow-sea bottom—began to accumulate throughout Europe.

Beginning at the close of the Mesozoic Era (66 MYA), and continuing through the Cenozoic Era to the present day, a complex orogeny has taken place in Europe. The ocean basin of Tethys was entirely destroyed, or if remnants still exist, they are indistinguishable from the ocean crust of the Mediterranean Sea. Africa has shifted from west of Europe (and up against the United States’ east coast) to directly south of Europe, and their respective tectonic plates are now colliding.

As in the collision that made the Variscan mountain belt, a couple of dozen little blocks are being pushed sideways into southern Europe. The tectonic arrangement can be compared with a traffic jam in Rome or Paris, where numerous moving objects attempt to wedge into a space in which they can’t all fit.

The Mediterranean desert

When sea level fell below the level of the Straits of Gibraltar around six million years ago, the western seawater passage from the Atlantic Ocean to the Mediterranean Sea closed, and water ceased to flow through this passage. At about the same time, northward-moving Arabia closed the eastern ocean passage out of the Mediterranean Sea and the completely landlocked ocean basin began to dry up. Not once, but perhaps as many as 30 times, all the water in the ancestral Mediterranean, Black, and Caspian Seas completely evaporated, leaving a thick crust of crystallized sea minerals such as gypsum, sylvite, and halite. It must have been a lifeless place, filled with dense hot air, like modern below-sea-level deserts such as Death Valley and the coast of the Dead Sea. The rivers of Europe, Asia, and Africa carved deep valleys in their respective continental slopes as they dropped down to disappear into the burning ldquo; wasteland.

Many times, too, the entire basin flooded with water. A rise in global sea level would lift water from the Atlantic Ocean over the Barrier Mountains at Gibraltar. Then the waters of the Atlantic Ocean would cascade 2.4 miles (4 km) down the mountainside into the western Mediterranean basin. From Gibraltar to central Asia, the bone-dry basin filled catastrophically in a geological instant—a few hundred years. This “instant ocean” laid deep-sea sediment directly on top of the layers of salt. The widespread extent and repetition of this series of layers of salt and deep-sea sediment layers is the basis for the theory of numerous catastrophic floods in the Mediterranean basin.

Pleistocene Europe

For reasons not yet fully understood, Earth periodically experiences episodes of planet-wide, climatic cooling, the most recent of which is known as the Pleistocene Epoch. Large areas of the land and seas become covered with ice sheets thousands of feet thick that remain unmelted for thousands or hundreds of thousands of years. Since the end of the last ice age about eight to twelve thousand years ago, only Greenland and Antarctica remain covered with continent-sized glaciers. But during the last two million or so years, Europe’s northern regions and its mountain ranges were ground and polished by masses of water frozen into miles-thick continental glaciers.

This ice age began in Europe when heavy snowfalls accumulated in Scandinavia and northern Russia. As the planet’s climate cooled, summer’s snowmelt did not remove all of winter’s snowfall, and an increasingly thick layer of ice accumulated. Ice built up higher and higher in some areas, and eventually began flowing out from these ice centers. As the ice sheet spread over more of the continent, its brilliant surface reflected the sun’s heat back out into space—cooling the climate even more. During several intervals, each lasting hundreds of thousands of years, the European ice sheet covered Scandinavia, northern Russia, all the lands around the Baltic Sea, and the British Isles. Ice caps covered the mountain ranges of Europe. Between these planetary deep-freezes were warm, or interglacial, intervals, some of them hundreds of thousands of years long.

Ice in glaciers is not frozen in the sense of being motionless. It is in constant motion, imperceptibly slow—but irresistible. Glaciers subject the earth materials beneath them to the most intense kind of scraping and scouring. An alpine glacier has the power to tear bedrock apart and move the shattered pieces miles away. These are the forces that shaped the sharp mountain peaks and u-shaped mountain valleys of modern Europe. Many European mountain ranges bear obvious scars from alpine glaciation, and the flat areas of the continent show the features of a formerly glaciated plain.

Each time the cooling climate froze the equivalent of an ocean of water into glaciers, the global sea level fell drastically (100 feet [30 m] or more). Southern England became a western promontory of the main European landmass, and the North Sea’s seabed lay exposed to the sky. The Adriatic Sea almost disappeared, and its seabed became an extension of the Po River alley. Sardinia and Corsica were at that time one island, and Sicily became a peninsula of mainland Europe.

Unusual geographic conditions also followed the retreat of the ice sheets. Bare rock was exposed in many areas. Elsewhere unvegetated sediment, deposited by the melting glaciers, lay exposed to the elements. Windstorms removed tremendous amounts of the smaller-sized grains in this sediment, and carried it far from where the glacier left it. The wind-blown sediment eventually settled out of the sky and formed layers of silt, called loess. Today, loess deposits form a broad belt in various regions from northern France to Russia, and beyond. These deposits originally must have covered almost all of central and eastern Europe.

Continental glaciation occurred several times during the last 2.2 million years. Geologists do not agree whether the ice will return again or not. However, even if the present climate is merely a warm period between glaciations, tens or hundreds of thousands of years may elapse before the next advance of the ice sheets.

Holocene Europe

Humans have lived in Europe for much of the Pleistocene epoch and the entire Holocene epoch (beginning at the end of the last ice age, about 10,000 years ago). During the past few thousand years, humans have significantly altered the European landscape. Wetlands across Europe have been drained for agricultural use from the Bronze Age onward. The Netherlands is famous for its polder, below-sea-level lands made by holding back the sea with dikes. Entire volcanoes (cinder cones) have been excavated to produce frost-resistant road fill.

Europe’s heavily industrialized regions developed in their present locations as a result of geologic factors. The industrial districts are centered around places where transportation routes carved by rivers occurred in conjunction with ore deposits and fossil fuels.

Europe continues to change today. From the Atlantic coast of Iberia to the Caucasus, Europe’s southern border is geologically active, and will remain so effectively forever, from a human frame of reference. Africa, Arabia, and the Iranian Plateau all continue to move northward, which will insure continued mountain-building in southern Europe.

Geologists are concerned about volcanic hazards, particularly under the Bay of Naples and in the Caucasus. Smaller earthquakes, floods, and other natural disasters happen every year or so. In historic times, in the Aegean Sea and at Pompeii, Herculaneum, and Lisbon, entire cities have been devastated or destroyed by volcanoes, earthquakes, and seismic sea waves. These larger-scale natural disasters can and will continue to happen in Europe on an unpredictable schedule with predictable results.

Miscellaneous regions and events

Britain and Ireland

The northwest fringe of Europe is made up of the two very old islands, Great Britain and Ireland, and numerous smaller islands associated with them. Geologically, these islands are a part of the European continent, although culturally separate from it. Unlike many islands of comparable size, the British Isles do not result from a single group of related tectonic events. They are as complex as continents themselves, which in the last two centuries has provided plenty of subject matter for the new science of geology.

Scotland and Ireland are each made of three or four slices of continental crust. These slices came together around 400 million years ago like a deck of cards being put back together after shuffling.

Iberia

The Iberian Peninsula, occupied today by Portugal and Spain, is one of the pieces of lithosphere that was welded to Europe during the Variscan mountain-building event. Like Britain, it is an unusual “micro-continent” with a complex geologic history.

Alpine and related orogenies

Since the Paleozoic era, southern Europe has continued to acquire a jumbled mass of continental fragments from Africa. Even today, the rocks of Europe from the Carpathian mountains southwestward to the Adriatic and Italy are made up of “tectonic driftwood,” and are not resting on the type of solid, crystalline basement that underlies Scandinavia and Ukraine.

Since the late Mesozoic Era, the widening Atlantic Ocean has been pushing Africa counterclockwise. All the blocks of lithosphere between Africa and Europe, including parts of the Mediterranean seafloor, will in all likelihood eventually become a part of Europe.

The Alps resulted from Europe’s southern border being pushed by the northern edge of Africa. In Central Europe, freshly made sedimentary rocks of early Mesozoic age, along with the older, metamorphosed, Variscan rocks below, were pushed into the continent until they had no other way to go but up. Following the path of least resistance, these rocks were shaped by powerful forces into complex folds called nappes, which means tablecloths in French. The highly deformed rocks in these mountains were later carved into jagged peaks by glaciers during the Pleistocene epoch.

The Jura Mountains, the Carpathians, and the Transylvanian Alps are made of stacks of flat-lying sedimentary rock layers. These mountain ranges were thrust forward in giant sheets out in front of the rising Alps.

A complex story of tectonic movement is recorded in the sea-floor rocks of the western Mediterranean. Corsica, Sardinia, Iberia, and two pieces of Africa called the “Kabylies”—formerly parts of Europe— moved in various directions at various speeds throughout the Cenozoic era.

On the western Mediterranean floor, new oceanic lithosphere was created. A subduction zone formed as an oceanic plate to the east sank below the western Mediterranean floor. The magma generated by this event gave rise to the Appenine Mountains, which formed as an island arc on the eastern edge of the western Mediterranean oceanic plate. The Appenines began to rotate counterclockwise into their present position. The Tyrrhenian Sea formed as the crust stretched behind this forward-moving island arc. In the Balkans, blocks of lithosphere have piled into each other over tens of millions of years.

The Dinarides and Hellenides, mountains that run down the east coast of the Adriatic Sea, form the scar left after an old ocean basin closed. The compressed and deformed rocks in these mountain ranges contain pieces of ocean floor. Just east of these seacoast mountains is a clearly recognized plate boundary, where the European and African plates meet. The boundary runs from the Pannonian Basin (in Hungary, Romania, and Yugoslavia), cuts the territory of the former Yugoslavia in half, and winds up in Greece’s Attica, near Athens.

Further inland, the Pannonian Basin results from the lithosphere being stretched as the Carpathian mountains move eastward and northward.

The Aegean Sea seems to have formed as continental crust has been stretched in an east-west direction. It is a submerged basin-and-range province, such as in the western United States. The Pelagonian Massif, a body of igneous and metamorphic rock that lies under Attica, Euboea, and Mount Olympus, forms part of the Aegean sea floor. The Rhodopian Massif, in northern Greece, Bulgaria, and Macedonia, also extends beneath the Aegean Sea. Faults divide the ridges from the troughs that lie between them. The

KEY TERMS

Archean eon— The interval of geologic time from 3.8 billion years ago to 2.5 billion years ago.

Baltica— The oldest part of Europe, made of rocks formed between 3.8 and 2.5 billion years ago, that underlies Scandinavia, the Baltic states, Poland, Belarus, and much of western Russia and Ukraine.

Collisional mountain belt— A mountain range, like the Alps, caused by one continent running into another continent.

Continental arc— A volcanic mountain range, such as existed in Europe’s geologic past, that forms on the tectonically active edge of a continent, over a subduction zone.

Craton— The part 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. Baltica is considered to be a craton to which the rest of Europe is attached.

Fault-block mountains— A mountain range formed by horizontal forces that squeeze a continent, fracturing its crust and pushing some crustal blocks upward to form mountains while others drop down to form valleys.

Hadean eon— The interval of geologic time from the beginning of earth (4.65 billion years ago) to 3.8 billion years ago.

Island arc— An curved row of islands of volcanic origin that develops where two lithospheric plates converge, usually near the edge of a continent, and associated with the formation of a deep trench parallel to the arc as oceanic crust is subducted.

Phanerozoic eon— The interval of geologic time beginning 570 million years ago, the rocks of which contain an abundant record of fossilized life.

Precambrian— The combined Hadean, Archean and Proterozoic eons, the first four billion years of Earth’s history, and for which there is only a poor fossil record.

Proterozoic eon— The interval of geologic time beginning 2.5 billion years ago and ending 570 million years ago.

faults indicate that the troughs have dropped into the crust between the high ridges.

The Balkan range in Bulgaria is thought to mark the crumpled edge of the European craton—the Proterozoic-age rocks extending north into Russia.

Europe is also host to isolated volcanoes related to structural troughs within the continent. The Rhine River flows in a trough known as the Rhine Graben. Geologists believe The Rhine once flowed southward to join the Rhone river in France, but was diverted by upwarping of the crust around the Vogelsberg volcano. The Rhine then changed its course, flowing out to meet England’s Thames river in the low-sea-level ice age.

Resources

BOOKS

Hancock P. L. and Skinner B. J., eds. The Oxford Companion to the Earth. Oxford: Oxford University Press, 2000.

Winchester, Simon, and Soun Vannithone. The Map That Changed the World: William Smith and the Birth of Modern Geology. New York: Perennial, 2002.

PERIODICALS

Hoffman, P., ed. “Stonehenge Blues.” Discover 11 (October 1990): 10.

OTHER

Carius, Alexander, and Kurt M. Lietzmann, eds. Environmental Change and Security: A European Perspective (Contributions to the International and European Environmental Policy). Berlin: Springer Verlag, 2002.

Geology.com. “Plate Tectonics: Pangaea Continent Maps”<http://geology.com/pangea.htm> (accessed November 16, 2006).

W. W. Norton and Company. “Essentials of Geology: An Introduction to the Planet Earth; Chapter 2: The Way the Earth Works: Plate Tectonics” <http://www.wwnorton.com/earth/egeo/animations/ch2.htm> (accessed November 24, 2006).

Europe

The continent of Europe is a landmass bounded on the east by the Ural mountains, on the south by the Mediterranean Sea, and on the north and west by the Arctic and Atlantic Oceans. Numerous islands around this landmass are considered a part of Europe. Europe is also the westernmost part of the Eurasian supercontinent (several continental masses joined together).

Europe holds a unique place among the continents; much of it is "new," in geologic terms. Unlike other continents whose structures seem simple in comparison, Europe is a collection of all different kinds of geologic regions located side by side, many of which have little or nothing to do with each other. This should be kept in mind when reading about the regions in this article, which are not areas of similar origins, but rather areas of dissimilar origin that happen to be part of the same continent.

Forces that made Europe

Plate tectonics is the main force of nature responsible for the geologic history of Europe. This continent-building process may be simply explained:

The earth is covered by a thin, brittle layer called the lithosphere. This term is used here interchangeably with "the Earth's crust." Below the lithosphere is the asthenosphere, where solid rock stretches and flows. The lithosphere is composed of sections, called plates, and floats on top of the asthenosphere , because it is less dense than the asthenosphere. The motion of a tireless heat engine swirls and stirs the asthenosphere, moving the plates.

Over hundreds of millions of years, the plates have come together to form continents, including Europe. Other processes, such as sedimentation and erosion , modify the shape of the land that has been forged by plate tectonics .

Large-scale geologic elements of Europe

European geologic history, like that of all the continents, involves the formation of the following features as a result of plate tectonics:

Island arcs: When the edge of a plate of Earth's lithosphere runs over another plate, forcing the lower plate deep into the elastic interior, a long, curved chain of volcanic mountains usually erupts on the forward-moving edge of the upper plate. When this border between two plates forms in an ocean , the volcanic mountains constitute a string of islands (or archipelago). This is called an island arc. Italy's Appenine mountains originally formed as an island arc, then became connected into a single peninsula later.

Continental arcs: A continental arc is exactly like an island arc except that the volcanos erupt on a continent, instead of in the middle of an ocean. The chemical composition of the erupted rock is changed, because old continental rocks at the bottom of the lithosphere have melted and mixed with the magma . A clear-cut example of this kind of mountain chain no longer exists in Europe, but ancient continental arcs once played an important part in Europe's geologic past. Sicily's Mt. Aetna and Mt. Vesuvius on the Bay of Naples are good examples of the type of volcano that commonly make up a continental arc.

Sutures: A suture describes the place where two parts of a surgery patient's tissue are sewed or rejoined; it also describes the belts of mountains that form when two continents are shoved into each other, over tens of millions of years, to become one. The Alps and other ranges in southern Europe stand tall because of a continental collision between Europe and Africa . The Alps, and other European ranges, are the forerunners of what may be a fully developed suture uniting Europe and Africa. This suture would be a tall mountain range that stretches continuously from Iberia to easternmost Europe.

The collision of Africa with Europe is a continuous process that stretches tens of millions of years into the past and into the future. All the generations of humanity together have seen only a tiny increment of the continental movement in this collision. However, throughout history people have felt the collision profoundly, in earthquakes and volcanos, with all the calamities that attend them.

Rifts: Sometimes a continent is torn in pieces by forces moving in opposite directions beneath it. On the surface, this tearing at first makes a deep valley, which experiences both volcanic and earthquake activity. Eventually the valley becomes wide and deep enough that its floor drops below sea level , and ocean water moves in. This process, called rifting, is the way ocean basins are born on Earth; the valley that makes a place for the ocean is called a rift valley. Pieces of lithosphere, rifted away from Africa and elsewhere, have journeyed across the Earth's surface and joined with the edge of Europe. These pieces of lithosphere lie under southern England, Germany, France, and Greece, among other places.

Fault-block mountains: When a continent-sized "layer cake" of rock is pushed, the upper layers move more readily than the lower layers. The upper layers of rock are heavy-but easier to move than those beneath it (like a full filing cabinet is heavy-but when it's pushed, it moves more easily than the floor beneath it). Between near surface rocks and the deeper, more ancient crustal rocks, a flat-lying fault forms, also called a "detachment" fault (decollement in French). This horizontal crack, called a thrust fault, contains fluid (water, mostly). The same hydraulic force that makes hydraulic machines lift huge weights functions in this crack as well. The fluid is so nearly incompressible that a sizeable piece of a continent can slide on it when pushed. The fault block floats on fluid pressure between the upper and lower sections of the lithosphere like a fully loaded tractor trailer gliding effortlessly along a rain-slicked road. The mountains that are heaved up where the thrust fault reaches the surface are one kind of fault block mountains. Both the Jura mountains and the Carpathians are fault block mountains.

Another kind of fault block mountain comes from stretching of the earth's lithosphere. The lithosphere, like any other brittle material, develops cracks perpendicular to the direction of movement of the forces that are pulling it apart. In this case the force is lateral, so steep, nearly vertical faults form.

However they form, physical and chemical forces start wearing down mountain ranges while they are still rising. Europe has been criss-crossed by one immense range of mountains after another throughout its almost four-billion year history. Where did these mountains go?

If mountains are not continuously uplifted, they are worn down by erosion in a few million years. In Europe's geologic past, eroded particles from its mountains were carried by streams and dumped into the surrounding ocean or the continent's inland seas. Those particularrivers and seas are now gone from Earth, 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 ever stood in Europe still exist, and much of the sand and clay into which the mountains were transformed still exists also, as rock or soil formations.

European geologic history

Unfortunately, the farther back in a continent's history we attempt to explore, the less we can know about it. Only a very incomplete record of ancient geologic events is preserved for study because most ancient rocks are subsequently destroyed. For the most distant geologic time interval in Europe's history, from 4.6 billion years ago (b.y.a.) to 3.8 b.y.a., the Hadean eon, almost nothing is known and so it is not discussed here. Enough is known however about the Archean eon (3.8-2.5 b.y.a.), the Proterozoic eon (2.5 b.y.a.-570 million y.a.), and the Phanerozoic eon (570 m.y.a.-present) to provide a fairly detailed picture. In fact, the events of the Phanerozoic eon are known well enough to discuss them with even smaller geologic time intervals. These from largest to smallest are era, period, and epoch. The older the events, the less detail is known, so only very recent geologic epochs are discussed.

Archean rocks in Europe

Europe was not formed in one piece, or at one time. Various parts of it were formed all over the ancient world, over a period of four billion years, and were slowly brought together and assembled into one continent by the processes of plate tectonics. What is now called Europe began to form more than 3 billion years ago, during the Archean eon.

Most geologists feel that prior to and during the creation of the oldest parts of Europe, Earth only superficially resembled the planet we live on today. Active volcanos and rifts abounded. The planet had cooled enough to have a solid crust and oceans of liquid water. 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 earth's most ancient crustal rocks, moved across the surface of a frantic crazy-quilt planet. Whatever it truly was like, the oldest regions in Europe were formed in this remote world. These regions are in Finland, Norway (Lofoten Islands), Scotland, Russia, and Bulgaria.

Proterozoic Europe

The piece of Europe that has been in its present form for the longest time is the lithospheric crust underneath Scandinavia, the Baltic states, and parts of Russia, Belarus, and Ukraine. This region moved around on its own for a long time, and is referred to as Baltica. It is the continental core, or craton, to which other parts were attached to form Europe.

In the two billion years of the Proterozoic eon (2.5 b.y.a to 570 m.y.a.), the 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. Erosion clogged the rivers with mud and sand, because no land plants protected the earth's barren surface from the action of rain, wind , heat, and cold.

During the late Proterozoic an existing supercontinent began to break up. One of the better known episodes in this supercontinent's dismemberment was the Pan-African event. This was a period when new oceans opened up and mountains rose all around Africa. Over a period of a quarter-billion years, relatively small pieces of Africa tore away and were rafted along on the asthenosphere, colliding with Baltica. These blocks include: the London Platform (southern Britain); a strip of Ireland from between counties Wicklow and Kerry; the Iberian Peninsula (Spain and Portugal); Aquitaine, Armorica, and the Massif Central (France); the Inter-alpine region (Switzerland and Austria); the Austrian Alps (Carnic Alps); Bohemia; Moesia (Bulgaria and Romania); and the Rhodope region (Northern Greece, Bulgaria, and European Turkey, including Istanbul).

The result is that much of northern and central Europe, on a continental scale of reference, is made of blocks of Africa stuck together in a "paste" of sedimentary rock .

Most of the mountain belts created in the Proterozoic eon have long since worn away. The roots of these mountain belts are found in northern Europe and include:

The Karelian mountain belt, forming the middle third of Norway, Sweden, and Finland, including some of Karelia, is underlain by the worn-flat roots of the Karelian mountain range. This orogenic event (from oros, Greek for mountain, and genesis, Greek for origin) happened between 2 billion and 1.7 billion years ago.

The Svecofennian mountain belt, forming most of the southern third of Norway, Sweden, and Finland, are the roots of a Proterozoic mountain belt. They lie hidden beneath recent glacier-deposited sediments, and beneath dense coniferous forests . Because these factors make examination difficult, the Svecofennian mountain-building event is not yet well understood. It is presumed that the Svecofennian mountain belt marks where Baltica's edge was between 1.9 and 1.4 billion years ago. This mountain belt rose in a time of worldwide mountain-building, and it may have been related to the assembly of North America's Canadian Shield.

The southernmost tips of Norway and Sweden were made in the SvecoNorwegian/Grenville orogenic event, between 1.2 and 0.9 billion years ago. This is the mountain chain that united Baltica with North America , before most of the western and southern parts of the European landmass existed.

The Ukrainian shield: At present, geologists do not agree on when or how the Ukrainian shield was put together. Parts of it were definitely in existence before the Proterozoic eon. During the Proterozoic it was assembled, and joined Baltica.

Paleozoic Europe

The sea washed over the oldest parts of Earth's surface many times during the three billion-plus years of Archean and Proterozoic history. Life flourished in the shallow tidewater for these 3,000 million years. Algae, one of the most ancient organisms, were 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 fossilspreserved under very rare conditions-remain from the entire world's immense Precambrian, or combined Hadean, Archean and Proterozoic, rock records.

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 (from the Greek phaneros, meaning visible, and zoe, meaning life), which includes the time interval from 570 million years ago to the present day. The seas teemed with creatures whose bones and shells we have come to know in the fossil record. These include trilobites, brachiopods , the first fishes, and vast coral reefs. The first half of the Phanerozoic eon is called the Paleozoic era (from the Greek palaios, meaning ancient). For Europe, the Paleozoic era was largely a continuation of events that started in the late Proterozoic eon.

Remember, the map of the ancient Earth didn't look anything like a modern world map. As this new day of Earth's history began, Baltica sat near the south pole. Three oceans surrounded it, and each of these oceans shrank and closed during the Paleozoic. As plate tectonics shifted island arcs and already-formed blocks of crust around on Earth's surface, new rock came to be a part of the forming continent of Europe; underground masses of igneous rock accumulated near active margins of Baltica; and volcanos frequently erupted even as they do today in the Mediterranean region. Concurrent with this volcanic mountain-building, was the wearing-down of the volcanos, and the wearing-down of mountain cores, exposed by erosion. The sediment from the erosion of these igneous rocks accumulated at the borders of the continental blocks, and often became compressed into tightly folded rock masses only a few million years after they accumulated.

Baltica faced Greenland across the Iapetus Ocean. Early in the Paleozoic Era, Europe combined again with North America to form a giant continent called Laurussia (from Laurentia, meaning the core of North America, and Russia), or The North Continent. The line along which the continents were welded together runs along the length of Norway, through central Scotland, south-central Ireland, and southern Wales. In North America this line runs down the eastern coast of Greenland. As always happens when continents collide, there an associated mountain-building event. The resulting mountains are called the Caledonides, and they stood athwart the seam that welded Baltica and Laurentia together at that time. A continental arc developed, running from Denmark southeast down the ancient coast of Baltica, which is also considered to be a part of the Caledonian orogeny. Mountains in Norway, Scotland, Wales, and Ireland bear the shapes of folds made in the Caledonian orogeny. They shed sediment as they eroded, and a great volume of sand came to rest in the British Isles (then scattered to areas throughout the region). These sandstone masses attracted the attention of early British geologists, who named them the Old Red Sandstone. They proposed that there had been a continent to the west that had entirely worn away, which they called the Old Red Sandstone continent. This continent is now known to have been the Greenland coast of Laurentia.

The Uralian Ocean lapped at Baltica's northeastern coastline. Just before the end of the Paleozoic era, the Ural ocean that had washed the eastern shore of Baltica narrowed and closed forever. Two landmasses—Siberia and Kazakhstan—compressed and lifted the sediments of the Ural ocean basin into the Ural mountains. The Urals still stand today, and mark the eastern boundary of Europe within the Eurasian supercontinent.

Africa faced Baltica across the Tornquist Sea. (Two oceans that later lay between Africa and Europe, at different times, are called Tethys. Earlier versions of Tethys are called Paleo-Tethys, and later versions of it are called Neo-Tethys. No Tethys ocean exists today.) Near the close of the Paleozoic Era (245 m.y.a.), Laurussia united with the single southern supercontinent made up of much of the rest of the world's continents, named Gondwana. This created the Pangea (from the Greek pan, meaning all, and Ge, meaning Earth). The Central Pangean mountains arose from this mighty collision, and deformed the rocks laid down during the Paleozoic in central Europe. These mountains joined to the west with the Mauretanides of West Africa, and the Appalachians and Ouachitas of the eastern and southern United States to form a tremendous mountain range stretching along the equator for more than 4,200 mi (7000 km). The whole mountain range is called the Hercynian Mega-suture.

Piece by piece, continental fragments tore away from Africa's northern and western shores and were crushed into the jagged southern edge of Baltica. The same processes that transported these blocks of Europe also deformed them, often changing the crystalline fabric of the rock so much that the original igneous or sedimentary rock type can only be guessed. Between Africa and Europe, tectonic forces seem to have pushed miniature continental blocks in several directions at once-the reconstructions of this time are still unclear. The violently twisted line followed by the Variscan mountain belt anticipated the Alps and other ranges of modern Europe.

Many important rock bodies, called massifs, formed as parts of the Variscan mountains. Giant, bulbous masses of granite and other igneous rocks solidified to form England's Cornwall; Spain and Portugal's Cantabrian Massif; France's Armorican Massif, Massif Central, and the Vosges; Germany's Black Forest; and the Erzgebirge Mountains on the German-Czech border. The Balkans also contain Variscan-age massifs.

Mesozoic and Cenozoic Europe

At the opening of the Mesozoic era, 245 million years ago, a sizeable part of western and southern Europe was squeezed up into the Central Pangean mountain system that sutured Laurussia and Gondwana together. Europe was almost completely landlocked, its southern regions part of a mountain chain that stretched from Kazakhstan to the west coast of North America.

The birth of a new ocean basin , the Atlantic, signaled the end of Pangaea. The Central Pangean Mountains, after tens of millions of years, had worn down to sea level and below. A new ocean basin, not the Mediterranean, but rather the Ligurean Ocean, began to open up between Africa and Europe. This formed a seaway between the modern North Atlantic and the Neo-Tethys Ocean (which no longer exists). Sea water began to leave deposits where high mountains had stood, and a layer cake of sediment-laid down on the shallow-sea bottom-began to accumulate throughout Europe.

Beginning at the close of the Mesozoic era (66 m.y.a.), and continuing through the Cenozoic era to the present day, a complex orogeny has taken place in Europe. The ocean basin of Tethys was entirely destroyed, or if remnants still exist, they are indistinguishable from the ocean crust of the Mediterranean Sea. Africa has shifted from west of Europe (and up against the United States' East Coast) to directly south of Europe, and their respective tectonic plates are now colliding.

As in the collision that made the Variscan mountain belt, a couple of dozen little blocks are being pushed sideways into southern Europe. The tectonic arrangement can be compared with a traffic jam in Rome or Paris, where numerous moving objects attempt to wedge into a space in which they can't all fit.

The Mediterranean desert

When sea level fell below the level of the Straits of Gibraltar around six million years ago, the western seawater passage from the Atlantic Ocean to the Mediterranean Sea closed, and water ceased to flow through this passage. At about the same time, northward-moving Arabia closed the eastern ocean passage out of the Mediterranean Sea and the completely landlocked ocean basin began to dry up. Not once, but perhaps as many as 30 times, all the water in the ancestral Mediterranean, Black, and Caspian seas completely evaporated, leaving a thick crust of crystallized sea minerals such as gypsum, sylvite, and halite (salt ). It must have been a lifeless place, filled with dense, hot air like modern below-sea-level deserts such as Death Valley and the coast of the Dead Sea. The rivers of Europe, Asia , and Africa carved deep valleys in their respective continental slopes as they dropped down to disappear into the burning salt wasteland.

Many times, too, the entire basin flooded with water. A rise in global sea level would lift water from the Atlantic Ocean over the barrier mountains at Gibraltar. Then the waters of the Atlantic Ocean would cascade 2.4 mi (4 km) down the mountainside into the western Mediterranean basin. From Gibraltar to central Asia, the bone-dry basin filled catastrophically in a geological instant—a few hundred years. This "instant ocean" laid deep-sea sediment directly on top of the layers of salt. The widespread extent and repetition of this series of salt and deep-sea sediment layers is the basis for the theory of numerous catastrophic floods in the Mediterranean basin.

Pleistocene Europe

For reasons not yet fully understood, the Earth periodically experiences episodes of planet-wide, climatic cooling, the most recent of which is known as the Pleistocene Epoch. Large areas of the land and seas become covered with ice sheets thousands of feet thick that remain unmelted for thousands or hundreds of thousands of years. Since the end of the last ice age about eight to twelve thousand years ago, only Greenland and Antarctica remain covered with continent-sized glaciers . But during the last two million or so years, Europe's northern regions and its mountain ranges were ground and polished by masses of water frozen into miles-thick continental glaciers.

This ice age began in Europe when heavy snowfalls accumulated in Scandinavia and northern Russia. As the planet's climate cooled, summer's snowmelt did not remove all of winter's snowfall, and an increasingly thick layer of ice accumulated. Ice built up higher and higher in some areas, and eventually began flowing out from these ice centers. As the ice sheet spread over more of the continent, its brilliant surface reflected the sun's heat back out into space—cooling the climate even more. During several intervals, each lasting hundreds of thousands of years, the European ice sheet covered Scandinavia, northern Russia, all the lands around the Baltic Sea, and the British Isles. Ice caps covered the mountain ranges of Europe. Between these planetary deep-freezes were warm, or interglacial, intervals, some of them hundreds of thousands of years long.

Ice in glaciers is not frozen in the sense of being motionless. It is in constant motion, imperceptibly slow-but irresistible. Glaciers subject the earth materials beneath them to the most intense kind of scraping and scouring. An alpine glacier has the power to tear bedrock apart and move the shattered pieces miles away. These are the forces that shaped the sharp mountain peaks and u-shaped mountainvalleys of modern Europe. Many European mountain ranges bear obvious scars from alpine glaciation, and the flat areas of the continent show the features of a formerly glaciated plain.

Each time the cooling climate froze the equivalent of an ocean of water into glaciers, the global sea level fell drastically (100 ft [30 m] or more). Southern England became a western promontory of the main European landmass, and the North Sea's seabed lay exposed to the sky. The Adriatic Sea almost disappeared, and its seabed became an extension of the Po River Valley. Sardinia and Corsica were at that time one island, and Sicily became a peninsula of mainland Europe.

Unusual geographic conditions also followed the retreat of the ice sheets. Bare rock was exposed in many areas. Elsewhere unvegetated sediment, deposited by the melting glaciers, lay exposed to the elements. Windstorms removed tremendous amounts of the smaller sized grains in this sediment, and carried it far from where the glacier left it. The wind-blown sediment eventually settled out of the sky and formed layers of silt, called loess ("lurse"). Today, loess deposits form a broad belt in various regions from northern France to Russia, and beyond. These deposits originally must have covered almost all of central and eastern Europe.

Continental glaciation occurred several times during the last 2.2 million years. Geologists do not agree whether the ice will return again or not. However, even if the present climate is merely a warm period between glaciations, tens or hundreds of thousands of years may elapse before the next advance of the ice sheets.

Holocene Europe

Humans have lived in Europe for much of the Pleistocene epoch and the entire Holocene epoch (beginning at the end of the last ice age, about 10,000 years ago). During the past few thousand years, humans have been significantly altering the European landscape. Wetlands across Europe have been drained for agricultural use from the Bronze Age onward. The Netherlands is famous for its polders, below-sea-level lands made by holding back the sea with dikes. Entire volcanos (cinder cones) have been excavated to produce frost-resistant road fill.

Europe's heavily industrialized regions developed in their present locations as a result of geologic factors. The industrial districts are centered around places where transportation routes carved by rivers occurred in conjunction with ore deposits and fossil fuels .

Europe continues to change today. From the Atlantic coast of Iberia to the Caucasus, Europe's southern border is geologically active, and will remain so effectively forever, from a human frame of reference. Africa, Arabia, and the Iranian Plateau all continue to move northward, which will insure continued mountain-building in southern Europe.

Geologists are concerned about volcanic hazards, particularly under the Bay of Naples and in the Caucasus. Smaller earthquakes, floods, and other natural disasters happen every year or so. In historic times, in the Aegean Sea and at Pompeii, Herculaneum, and Lisbon, entire cities have been devastated or destroyed by volcanos, earthquakes, and seismic sea waves. These larger-scale natural disasters can and will continue to happen in Europe on an unpredictable schedule with predictable results.

Miscellaneous regions and events

Britain and Ireland

The northwest fringe of Europe is made up of the two very old islands, Great Britain and Ireland, and numerous smaller islands associated with them. Geologically, these islands are a part of the European continent, although culturally separate from it. Unlike many islands of comparable size, the British Isles do not result from a single group of related tectonic events. They are as complex as continents themselves, which in the last two centuries has provided plenty of subject matter for the new science of geology .

Scotland and Ireland are each made of three or four slices of continental crust. These slices came together around 400 million years ago like a deck of cards being put back together after shuffling.

Iberia

The Iberian Peninsula, occupied today by Portugal and Spain, is one of the pieces of lithosphere that was welded to Europe during the Variscan mountain-building event. Like Britain, it is an unusual "micro-continent" with a complex geologic history.

Alpine and related orogenies

Since the Paleozoic era, southern Europe has continued to acquire a jumbled mass of continental fragments from Africa. Even today, the rocks of Europe from the Carpathian mountains southwestward to the Adriatic and Italy are made up of "tectonic driftwood," and are not resting on the type of solid, crystalline basement that underlies Scandinavia and Ukraine.

Since the late Mesozoic era, the widening Atlantic Ocean has been pushing Africa counterclockwise. All the blocks of lithosphere between Africa and Europe, including parts of the Mediterranean seafloor, will in all likelihood eventually become a part of Europe.

The Alps resulted from Europe's southern border being pushed by the northern edge of Africa. In Central Europe, freshly-made sedimentary rocks of early Mesozoic age, along with the older, metamorphosed, Variscan rocks below, were pushed into the continent until they had no other way to go but up. Following the path of least resistance, these rocks were shaped by powerful forces into complex folds called nappes, which means tablecloth in French. The highly deformed rocks in these mountains were later carved into jagged peaks by glaciers during the Pleistocene epoch.

The Jura Mountains, the Carpathians, and the Transylvanian Alps are made of stacks of flat-lying sedimentary rock layers. These mountain ranges were thrust forward in giant sheets out in front of the rising Alps.

A complex story of tectonic movement is recorded in the sea-floor rocks of the western Mediterranean. Corsica, Sardinia, Iberia, and two pieces of Africa called the "Kabylies"—formerly parts of Europe—moved in various directions at various speeds throughout the Cenozoic era.

On the western Mediterranean floor, new oceanic lithosphere was created. A subduction zone formed as an oceanic plate to the east sank below the western Mediterranean floor. The magma generated by this event gave rise to the Appenine mountains, which formed as an island arc on the eastern edge of the western Mediterranean oceanic plate. The Appenines began to rotate counterclockwise into their present position. The Tyrrhenian Sea formed as the crust stretched behind this forward-moving island arc. In the Balkans, blocks of lithosphere have piled into each other over tens of millions of years.

The Dinarides and Hellenides, mountains that run down the east coast of the Adriatic Sea, form the scar left after an old ocean basin closed. The compressed and deformed rocks in these mountain ranges contain pieces of ocean floor. Just east of these seacoast mountains is a clearly-recognized plate boundary, where the European and African plates meet. The boundary runs from the Pannonian Basin (in Hungary, Romania, and Yugoslavia), cuts the territory of the former Yugoslavia in half, and winds up in Greece's Attica, near Athens.

Further inland, the Pannonian Basin results from the lithosphere being stretched as the Carpathian mountains move eastward and northward.

The Aegean Sea seems to have formed as continental crust has been stretched in an east-west direction. It is a submerged basin-and-range province, such as in the western United States. The Pelagonian Massif, a body of igneous and metamorphic rock that lies under Attica, Euboea, and Mount Olympus, forms part of the Aegean sea floor. The Rhodopian Massif, in northern Greece, Bulgaria, and Macedonia, also extends beneath the Aegean Sea. Faults divide the ridges from the troughs that lie between them. The faults indicate that the troughs have dropped into the crust between the high ridges.

The Balkan range in Bulgaria is thought to mark the crumpled edge of the European craton—the Proterozoicage rocks extending north into Russia.

Europe is also host to isolated volcanos related to structural troughs within the continent. The Rhine river flows in a trough known as the Rhine Graben. Geologists believe the Rhine once flowed southward to join the Rhone river in France, but was diverted by upwarping of the crust around the Vogelsberg volcano. The Rhine then changed its course, flowing out to meet England's Thames river in the low-sea-level ice age.

Resources

books

Hancock P. L., and B. J. Skinner, eds. The Oxford Companion to the Earth. Oxford: Oxford University Press, 2000.

Winchester, Simon, and Soun Vannithone. The Map That

Changed the World: William Smith and the Birth of Modern Geology. New York: Perennial, 2002.

periodicals

Hoffman, P., ed. "Stonehenge Blues." Discover 11 (October 1990): 10.

other

Carius, Alexander, and Kurt M. Lietzmann, eds. EnvironmentalChange and Security: A European Perspective (Contributions to the International and European Environmental Policy). Berlin: Springer Verlag, 2002.

KEY TERMS

Archean eon

—The interval of geologic time from 3.8 billion years ago to 2.5 billion years ago.

Baltica

—The oldest part of Europe, made of rocks formed between 3.8 and 2.5 billion years ago, that underlies Scandinavia, the Baltic states, Poland, Belarus, and much of western Russia and Ukraine.

Collisional mountain belt

—A mountain range, like the Alps, caused by one continent running into another continent.

Continental arc

—A volcanic mountain range, such as existed in Europe's geologic past, that forms on the tectonically active edge of a continent, over a subduction zone.

Craton

—The part 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. Baltica is considered to be a craton to which the rest of Europe is attached.

Fault block mountains

—A mountain range formed by horizontal forces that squeeze a continent, fracturing its crust and pushing some crustal blocks upward to form mountains while others drop down to form valleys.

Hadean eon

—The interval of geologic time from the beginning of Earth (4.65 billion years ago) to 3.8 billion years ago.

Island arc

—An curved row of islands of volcanic origin that develops where two lithospheric plates converge, usually near the edge of a continent, and associated with the formation of a deep trench parallel to the arc as oceanic crust is subducted.

Phanerozoic eon

—The interval of geologic time beginning 570 million years ago, the rocks of which contain an abundant record of fossilized life.

Precambrian

—The combined Hadean, Archean and Proterozoic eons, the first four billion years of Earth's history, and for which there is only a poor fossil record.

Proterozoic eon

—The interval of geologic time beginning 2.5 billion years ago and ending 570 million years ago.

EUROPE

Antiquity

The earliest contacts of the ancient Hebrews with Europe and Europeans were probably through the Greek traders who were familiar figures all over the eastern Mediterranean littoral as early as the eighth century b.c.e. It must however be borne in mind that the Hebrews were settled mainly in the uplands of Ereẓ Israel away from the coastal area, while the Greeks were at this time almost as much Asiatics as Europeans geographically. It was probably at the time of the First Exile after the fall of Jerusalem in 586 b.c.e. that Jews first penetrated into Europe. The Hebrew prophets, for instance Isaiah, speak more than once of the future redemption of the Jewish exiles from the "isles of the sea," by which presumably the Greek coastlands were implied, and it is likely enough that at this period Greek slave dealers purchased Jewish captives for sale on their domestic markets. Although their absorption in the Persian Empire confirmed the Asiatic nature of the Jewish people for a long period, that empire's expansionist ambitions westward to some extent opened it and its Jewish population to Western and European ideas and influences. After the return from Exile, Greek influences on the trading cities of the Palestinian littoral were becoming strong, and some later books of the Bible (e.g., Ecclesiastes) seem to show a distinct Hellenic coloring. It was, however, the conquests by *Alexander the Great in the fourth century b.c.e. that definitely changed the character of this area. Hitherto, Ereẓ Israel had been part of the Near Eastern Afro-Asiatic nexus, looking to, and influenced by, Syria, Assyria, and Babylonia to the north, the Arabian tribes to the east, and Egypt to the south. Alexander the Great broke down as it were the barrier that had hitherto divided this region from Europe. Henceforth, Ereẓ Israel looked west, not east, and, with the surrounding area, was part of the European nexus and sphere of influence, more or less sharply divided from Asia and the Asiatic powers. Insofar as it continued to be affected by the neighboring land areas, it was by those (Syria, Egypt) that had largely succumbed to Greek influences and could now be regarded almost as extensions of Europe. Although great masses of Jews remained under Partho-Persian rule in *Mesopotamia, the most important settlement outside Ereẓ Israel was in Greek-speaking *Alexandria, which had constant and intimate contacts with the centers of European life. It was here in fact in the ensuing period that the Jews produced their great Hellenistic literature, reaching its climax in *Philo and constituting their first literary expression in the language of European culture. From certain points of view, the *Hasmonean revolt in the second century b.c.e. could be considered a reaction against the tendency that has been described – an attempt to stem the inroads of European culture and to reassert Asiatic values. However, its success was only temporary. The Hasmonean monarchs, while asserting political independence, ultimately succumbed to some extent to European cultural influences. The Roman conquest of 63 b.c.e. brought Ereẓ Israel and its population – still the largest and most creative part of the Jewish people – under European rule and within the European cultural orbit. It is hardly an exaggeration to say that from now on, down to the Arab conquest in 640, Ereẓ Israel and its population constituted in effect part of Europe; and the European influences on the Jewish population there – and hence on Judaism itself – became increasingly strong.

Meanwhile the actual Jewish settlement in Europe was growing. From the third century b.c.e. Jews are mentioned in inscriptions, etc., on the mainland of *Greece. The early Hasmonean rulers had entered into diplomatic relations with *Rome, necessitating the dispatch of envoys thither, and there is a somewhat obscure reference to the expulsion of Jewish religious propagandists thence in 139 b.c.e. Thereafter, the wars of the Romans in Asia Minor and their conquest of Ereẓ Israel inevitably resulted in the arrival on the Roman slave market of Jewish captives (many of whom would win their freedom or else be ransomed by their coreligionists), while the capital of the empire inevitably attracted visitors, emissaries, and merchants. Rabbinic sources, the New Testament, and *Josephus all confirm the impression of a solid Jewish community there in the first century c.e., the subsequent importance of which is attested by several series of *catacombs and hundreds of inscriptions. As early as 59 b.c.e.*Cicero, in his oration in defense of Flaccus who had raided the Jewish temple offerings in the Greek islands, could assert that the Jews were present at the trial in Rome in such numbers as to overawe the court. Jews were also present at this period in many other places throughout *Italy, especially along the trade routes leading to the ports commanding trade with the East. The existence of Jewish settlements all over the Roman Empire in its heyday is recorded in Gaul (see *France), *Spain, Pannonia, even in the Rhineland (see *Germany), and it is probable that there was no Roman province without a Jewish settlement, even if no definite evidence is preserved. The total number involved was far from insignificant. The Jewish population of Rome has been estimated (with some exaggeration) at as many as 50,000, and it has been asserted that they constituted something like one-tenth of the population of the empire as a whole. The Jews of Europe, by the time of the breakup of the Roman Empire, were probably to be reckoned at some hundreds of thousands. On the other hand, their cultural significance was slight. They made barely the slightest contribution to rabbinic or Hebrew culture in the talmudic age, nor is any work of this period extant in Latin which is certainly of Jewish authorship.

Rise of Christianity and Islam

Under the Roman Empire, to the fourth century, the position of the Jews was on the whole good. Although looked down upon, both because of the "superstitions" to which they adhered and their lowly economic status, their religion was tolerated, and from 212 they enjoyed Roman citizenship with all its advantages and responsibilities along with the other free inhabitants of the empire. With the Christianization of the empire, however, their position deteriorated, though at first socially more than juridically, the ground being prepared for their systematic degradation which was to become the rule in Christian Europe in the Middle Ages. The Barbarian invasions probably affected the Jews, as a mainly urban element, more than the rest of the population, so that it seems their numbers were drastically reduced in this period. Moreover, the new rulers, once they adopted Christianity – especially in its Catholic form – were unable to preserve the delicate balance between sufferance and intolerance that had been achieved under the earlier Christian emperors – all the more so since this period witnessed the periodical triumph of religious fanaticism in the *Byzantine Empire, setting a baneful example to the rest of the Western world. Restrictions were imposed by the Church at an early date; from 305 successive *Church Councils repeatedly reissued discriminatory legislation. Hence the period between the fifth and eighth centuries was punctuated all over Europe by religious riots, coercion, compulsory baptisms, and widespread expulsions, culminating in the great disaster to the Jewish community of Spain under the Visigoths, about which we are particularly well informed. The Jewish population of Western Europe was now, it seems, reduced to relative unimportance, except perhaps in some parts of Italy.

Conditions changed for the better in the eighth century. The Arab conquests opened up Spain to new colonization which seems to have attained significant proportions – at first, it is true, in a quasi-Asiatic cultural setting – but this was destined to be temporary, waning with the Reconquest and the expansion of the Christian kingdoms. Simultaneously, and apparently with the sedulous encouragement of the Carolingian rulers in France, Italy, and Germany, Jewish merchants and traders (typified in the *Radanites who had their base in the Rhone delta) became active in Western, then in Central Europe, establishing a fresh nexus of Jewish communities or reinforcing the old. In Eastern Europe – an outlet for their exports of the manufactured products of the West, a source of their purchases of raw materials and slaves – they presumably joined up with older Jewish settlements that had spread northward from the Black Sea and Crimea or along the Danube valley. This period moreover coincided with that of the near-extinction of the old settlement in Ereẓ Israel and the drastic dwindling of that of Mesopotamia and the neighboring lands, due in part to political and in part to economic causes. The result was that in this period, approximately between 800 and 1050, there took place either a mass transference of the Jewish population from East to West, or else a phenomenal expansion of the one and dwindling of the other which had much the same effect. From the 11^th century, in any case, the center of Jewry and of Jewish intellectual life was transferred to Europe, where it was to remain for nearly 1,000 years. The new settlers were moreover of a different type in many respects from the old. They (especially those of Northern Europe) might be termed "Talmud Jews" who guided their lives in every respect according to the detailed prescriptions that had become evolved recently in Ereẓ Israel and especially Mesopotamia, and considered that the study of the Talmud was the greatest of religious duties and of personal pleasures. Hence, when the great talmudic academies of Mesopotamia decayed in the 11^th century, those of Northern Europe – especially France and the Rhineland – were ready to take their place; and the former rabbinic traditions were perpetuated there for centuries. In the south of Europe, particularly in Spain, a somewhat different intellectual tradition prevailed, literature, belles lettres, philosophy, and poetry attaining new heights. At the same time, the position of the Jews, straddling the Latin-Christian and the Arab-Islamic cultures, qualified them in a unique degree to perform the function of middlemen in intellectual as well as economic activities; and while on the one hand they participated in the scientific and philosophical activities of the Islamic world, on the other they were to a great extent responsible for the transference of the superb fruits of these activities to the 12^th-century Christian world, and so helped to bring about the Latin renaissance and the revival of learning in Europe.

Medieval Position

It is possible to exaggerate the well-being of the Jews in Europe in the Dark Ages, but there can be no question as to the great and tragic difference that resulted from the *Crusades. Hitherto, attacks on the Jews had been sporadic and occasional, but from the onslaught on the Jewish communities in France and the Rhineland in 1096 they became commonplace during any period of religious excitement or incitement; not only when the Christian forces marched against the infidels or heretics, but when such preposterous charges as that of the *blood libel (from 1141) or of the desecration of the *Host (after 1215) were brought up against the Jews. The stimulus given to European trade by the Crusades and the expansion of the Italian trading republics undermined the position of the Jewish international merchants. As a result of this, combined with the fact that at this period the Church's attack on the practice of usury reached its climax, the Jews of Northern Europe especially were now driven into the profession of *moneylending – encouraged and protected by their rulers, whose systematic and rapacious system of taxation converted this into a primary source of revenue for themselves. On the other hand, the profession of moneylending, besides affording ample leisure for the talmudic study that had become the all-pervading passion of Northern European Jewry, endowed them temporarily, in the intervals of spoliation, with a remarkable degree of economic well-being, so that the Jews of France, Germany, and *England in the Middle Ages constituted one of the most affluent nonnobiliary societies of the contemporary world. Thus, economic resentment was now added to the ever-increasing religious hatred. It was under the influence of this atmosphere that the fourth *Lateran Council of 1215 codified and reenacted the former anti-Jewish discriminatory legislation with innovations such as the enforcement of the wearing by the Jews of a distinctive humiliating *badge to distinguish them from other men. This henceforth remained a standard of conduct, to be enforced whenever the spirit of reaction triumphed. Such an attitude was increasingly intensified by the constant activity of the Christian mendicant orders, especially the *Dominicans, founded at this period precisely to combat heresy and unbelief. It was partly due to their influence that the Jews were expelled from England in 1290 and from France in 1306, their now diminished utility to the royal treasury being outweighed by the immediate profit of a single confiscatory measure. The Jews were absent from England henceforth until well after the end of the Middle Ages, and feeble attempts at reestablishment in France were unsuccessful.

Most of the refugees from these countries probably found their way ultimately to Germany, where political fragmentation prevented any similar wholesale measure, although the outbreaks of massacre, particularly at the time of the *Black Death of 1348–49, far outdid in scale and horror anything else of the sort known in medieval Jewish history. Hence it was only a feeble remnant that maintained the Jewish connection here unbroken. On the other hand, the greater security, and opportunities for profitable activity in an economically undeveloped area, drew Jews (as well as non-Jews) at this time to *Poland, now struggling for revival after the devastation wrought by Tatar invasions of the 13^th century. With the close of the Middle Ages this country became the essential bulwark of Jewish life in Europe, perpetuating the intellectual traditions of France and the Rhineland, still maintaining the colloquial German of their ancestors as their *Yiddish vernacular, and developing in the *Council of the [Four] Lands and the sister-bodies autonomous institutions hardly paralleled elsewhere in Diaspora history. Poland therefore became the center of "*Ashkenazi" Jewry, i.e., those of (Franco-) German origin.

Meanwhile, the condition of the Jews of Spain too, after reaching unprecedented heights of culture as well as of political influence even under the Christian kings, began to deteriorate owing to the constant propaganda of the friars. A wave of massacres in 1391 initiated the problem of the *Conversos or *Marranos or *New Christians, which inexorably led in due course to the establishment of the *Inquisition in 1484, and the Expulsion from Spain in 1492 and from *Portugal (leaving behind however a compact body of Marranos) in 1497. The refugees made their way in great numbers eastward, where they revived the flagging communities that had survived from Byzantine times. Turkey-in-Europe (see *Ottoman Empire; apart from Turkey-in-Asia, where the same occurred) thus became the great center of *Sephardi (or Spanish and Portuguese) Jewry, as Poland was of Ashkenazi Jewry, and the communities in *Constantinople, *Salonika, and other places preserved the ancient traditions of Spanish-speaking Jewry in islands of western Mediterranean culture transplanted to Eastern Europe.

Renaissance and Counter-Reformation

In the first half of the 16^th century, the Italian mainland (the Jews had been expelled from *Sicily and *Sardinia, with the rest of the Aragonese dominions, in 1492) had witnessed a remarkable development in Jewish cultural life and activity, in the spirit of the Renaissance. But this was changed by the Counter-Reformation. The Jews were expelled from the Kingdom of *Naples by its Spanish rulers in 1542; the old anti-Jewish code with new extensions was rigidly enforced in northern Italy (especially the papal dominions) from 1555 onward, accompanied by the institution of the *ghetto and heartless enforcement of the ghetto system henceforth invariable in Catholic Europe. Although Jewish communities continued to exist in the famous ghettos of *Rome, *Venice, *Mantua, etc., which, though not numerically large, played a great part in Jewish cultural life, a considerable proportion of Italian Jewry (especially from the center and south of the peninsula) was now absorbed in the Sephardi communities of the Near East. It is important, however, to note that these newly reestablished centers, under Muslim rule, whether or not in the geographical bounds of Europe, were henceforth basically European in culture, outlook, and language: segments as it were of medieval Europe embedded fossilwise in Asiatic or African soil.

The Renaissance and the accompanying movements established for centuries the predominance of Europe in the world politically, culturally, and scientifically. It hence confirmed the predominance of European Jewry over its coreligionists in other continents, most paradoxically, precisely at the time when most of Europe rejected, ejected, and excluded the Jews. Though European Jewry had led in every aspect of Jewish creativity since the beginning of the millennium, there had been solid collaboration hitherto from elements in other continents; from now on, the lead of Europe was overwhelmingly great, and so far as Jewish life in the other continents was concerned it was on the whole as protractions of European Jewish life. The development of *printing confirmed and accentuated this cultural hegemony. For four and a half centuries at least, almost all Hebrew printing was done in Europe – with the inevitable result that the European Hebrew texts in particular were accepted as classical, and new works by European Jewish scholars became universally accepted while others of perhaps equal merit might remain in manuscript and almost unknown in wider circles.

The culmination of the age of degradation was accompanied, however, by the glimmer of a new dawn. Marranos mainly from Portugal rather than Spain, settling at this period in Northern Europe for the sake of business more than freedom of conscience, ventured little by little to throw off the disguise of Christianity. By the end of the 16^th century, a number of new Jewish communities, hovering as yet on the borders of clandestinity, began to establish themselves in this area, where for generations no Jews had been known; and by the middle of the 17^th century there were at *Amsterdam, *Hamburg, and other cities (a little later in *London also) open Jewish communities of a new "modern" type, socially assimilated to the world around them.

In Eastern Europe, by this time, the Jews had become involved in the hatreds that had been engendered between the Roman Catholic Poles and their persecuted Greek Catholic subjects in the *Ukraine. In consequence, when the latter rose in revolt under the Cossack hetman *Chmielnicki in 1648–49, Jews as well as Poles suffered, the Jews even more than the Poles, the ensuing wave of massacres ending the days of tranquility that had hitherto been the rule there. Henceforth, the tide of emigration set in the reverse direction, from east to west, the communities of Germany, and thereafter of Western Europe, being considerably reinforced. This was intensified as generations passed and the condition of Polish Jewry constantly deteriorated. Conversely, at this period the emergence in Germany after the Peace of Westphalia (1648) of competing states and would-be resplendent courts gave opportunities such as had never existed before for lucrative activities for Jewish factors and *Court Jews, new Jewish communities often developing around them. Thus here too a new type of socially assimilated Jew began to emerge in the 17^th century, culminating in the 18^th in the remarkable figure of Moses *Mendelssohn, almost the first Jew to play a role of real importance in European cultural life.

Emancipation

Thus by the end of the 18^th century a new type of Jew had emerged in Western Europe. After the outbreak of the French Revolution it was hence inevitable that the new doctrine of Liberty, Equality, and Fraternity should be applied, at first reluctantly, to the Jews as well – that is, that they should be given the same rights, receive the same treatment, and have the same duties as other men. Or, to put it another way, they were now formally recognized as Europeans, differentiated from other Europeans by adherence to another faith. These new doctrines were moreover imposed by or imitated from the French almost all over the continent of Europe where Jews were to be found. A reaction followed the fall of Napoleon in 1815; but henceforth Jewish political equality was part of the liberal creed, and it was accepted almost everywhere by the

third quarter of the 19^th century (the crucial year may be fixed at 1870), Jewish *emancipation being henceforth the rule. Jews now began to play a role of increasing importance in European cultural, literary, scientific, social, and even political activity. At the same time, Jewish *assimilation became accelerated, both in the extreme form of conversion to the dominant faith, and in the more loyal form of the representation of Judaism simply as a divergent European religion – that is, *Reform Judaism, in all its branches and aspects (including *neo-Orthodoxy). The development of a Hebrew secular literature along European models (*Haskalah) and of vernacular literature on Hebrew scholarly themes (Wissenschaft des Judentums) were other aspects of this same tendency.

There was however one area where this new attitude did not apply, and the exception was numerically more important, and in its way more significant, than the rule. In *Russia (where there was no important Jewish settlement until the annexation of those areas of the old Polish kingdom which had the largest Jewish population) these were years not of progress but (with rare intervals) of reaction, and in 1881 a wave of massacres (*pogroms) began on a scale and of a type which recalled the Middle Ages, to be followed by economic and social restrictions of unprecedented scope (the *"May Laws"). A wave of emigration (see *migration) followed on a vast scale. This entirely changed the face of European Jewry within very few years. It greatly reinforced the Jewish communities of Western Europe, in particular that of England, and even changed their character. But far more important than this was the transatlantic migration. Emigration largely from Germany in the first three-quarters of the 19^th century had relieved the pressure of population in that country and at the same time greatly developed the Jewish community in the *United States of America. Now, within a few years, as a result of immigration from Eastern Europe, it was to be reinforced in fantastic proportions. The results were all-important. For eight centuries after approximately the year 1000, the essential center of Jewish life and creativity had been in Europe. Outside the European area there had been only relatively unimportant offshoots, and this applied in particular to Ashkenazi Jewry. After the 1880s the United States was to be the second, and in due course the first, center of Jewish life in the world, from the point of view of population, and the relative role of European Jewry correspondingly diminished. From the early Victorian era the Western European Jewish communities had taken the lead in political and charitable activities on behalf of their depressed coreligionists elsewhere. From now on, their preponderance waned, passing in an increasing degree to America. The process of emigration was paralleled in *Romania and *Galicia (then under Austrian rule). Between 1880 and 1914, about two million Jews from Eastern Europe transferred themselves to the New World. It is true that natural increase kept the total population level actually unchanged, but had it not been for the emigration it would have continued to rise enormously.

During this period, the ancient Sephardi communities of the Mediterranean area had been affected by quasi-lethargy. Although under the rule of Turkey and the Balkan successor states their material and political condition was on the whole not adverse, the spirit of creativity that had been so marked in Spain had now passed from them almost entirely.

World War i

World War i marked the beginning of a cataclysm in European Jewish life. The revolutions of 1917 brought the Russian Jews emancipation, but at the same time ushered in the Bolshevik regime which in the long run severed the mass of Russian Jews from their coreligionists abroad, and indeed from Judaism. On the other hand, the removal of the traditional residence restrictions, which had hitherto confined the Jews to the *Pale of Settlement, implied that henceforth they were spread more evenly throughout the vast Russian territories, in Asia as well as Europe. Although the rights of the Jews in the Succession States, which were severed mainly from Russia (especially Poland with a very large Jewish population), were nominally guaranteed by the Versailles treaties, the actuality fell short of this. The ensuing period was hence one of strain and perplexity, and emigration continued – though on a smaller scale than hitherto. Owing to restrictions in North America it was now largely directed to South America, and in part to Ereẓ Israel, as a result of the *Balfour Declaration which was specifically intended to help solve the problems of European Jewry.

Rise of Antisemitism and Nazism

In Germany, the dazzling progress of persons of Jewish extraction after Emancipation had given rise at the close of the 19^th century to the new racial *antisemitism. For a long while this had remained an annoyance rather than a menace, although in France the *Dreyfus case from 1894 to 1896 had caused a major political convulsion and convinced Theodor *Herzl that

the solution to the Jewish problem must be sought outside the setting of European life. The German defeat in World War i and the physical as well as moral distress that ensued gave the antisemitic movement in that country an enormous impetus, and it became a cardinal principle of the Nazi Party (see *National Socialism) which attained power in 1933. The persecution that ensued drove very large numbers of Jews from Germany and *Austria into exile, to other parts of Europe, to Ereẓ Israel, and to other continents. This, however, proved to be only a beginning. During World War ii, in the course of which the German armies overran almost all those parts of continental Europe in which Jewish communities existed, a systematic campaign of extermination was carried out. By the conclusion of hostilities in 1945, some 6,000,000 had perished in the *Holocaust out of the 9,000,000 who had lived in Europe in 1933, apart from the hundreds of thousands who had gone into exile; most of the greatest Jewish communities of the Continent – *Vienna, *Berlin, *Warsaw, *Lodz – had been annihilated. Many lands – including *Poland, *Yugoslavia, *Czechoslovakia, and even *Holland, as well as Germany and Austria – had become almost empty of Jews, most of the handful of survivors preferring to leave the blood-soaked soil. The great talmudic academies of Eastern Europe had been destroyed, as well as the center of Sephardi culture in the Balkans. Moreover, the Russian Jewish remnant seemed to be cut off from Jewish life even more completely than before, henceforth having no creative role to play.

The proportion of European Jewry in the world Jewish population declined in the course of half a century from 87.2% in 1880 to 58.05% in 1939, and then to 30% in 1968 and 12% in 2003. After approximately a thousand years, the European dominance in Jewish life has ended. It has on the one hand reverted to the ancestral soil in Asia; on the other, been transferred to the New World beyond the Atlantic Ocean.

For bibliography see *History, and individual countries and communities.

[Cecil Roth]

Europe

The continent of Europe is a landmass bounded on the east by the Ural Mountains, on the south by the Mediterranean Sea, and on the north and west by the Arctic and Atlantic Oceans . Numerous islands around this landmass are considered a part of Europe. Europe is also the westernmost part of the Eurasian supercontinent (several continental masses joined together). Europe is a collection of different kinds of geologic regions located side by side. Europe holds a unique place among the continents; much of it is new, in geologic terms.

Plate tectonics is the main force of nature responsible for the geologic history of Europe. European geologic history, like that of all the continents, involves the formation of features as a result of plate tectonics.

When the edge of a plate of Earth's lithosphere runs over another plate, forcing the lower plate deep into the elastic interior, a long, curved chain of volcanic mountains usually erupts on the forward-moving edge of the upper plate. When this border between two plates forms in an ocean, the volcanic mountains constitute a string of islands (or archipelago). This is called an island arc. Italy's Appenine Mountains originally formed as an island arc, then later became connected into a single peninsula.

A continental arc is exactly like an island arc except that the volcanos erupt on a continent, instead of in the middle of an ocean. The chemical composition of the erupted rock is changed, because old continental rocks at the bottom of the lithosphere have melted and mixed with the magma . A clear-cut example of this kind of mountain chain no longer exists in Europe, but ancient continental arcs once played an important part in Europe's geologic past. Sicily's Mt. Aetna and Mt. Vesuvius on the Bay of Naples are good examples of the type of volcano that commonly make up a continental arc.

A suture describes the place where two parts of a surgery patient's tissue are sewed or rejoined; it also describes the belts of mountains that form when two continents are shoved into each other, over tens of millions of years, to become one. The Alps and other ranges in southern Europe stand tall because of a continental collision between Europe and Africa . The Alps, and other European ranges, are the forerunners of what may be a fully developed suture uniting Europe and Africa. This suture would be a tall mountain range that stretches continuously from Iberia to easternmost Europe.

The collision of Africa with Europe is a continuous process that stretches tens of millions of years into the past and into the future. All the generations of humanity together have seen only a tiny increment of the continental movement in this collision. However, throughout history, people have felt the collision profoundly, in earthquakes and volcanos, with all the calamities that attend them.

Sometimes a continent is torn in pieces by forces moving in opposite directions beneath it. On the surface, this tearing at first makes a deep valley, which experiences both volcanic and earthquake activity. Eventually the valley becomes wide and deep enough that its floor drops below sea level, and ocean water moves in. This process, called rifting , is the way ocean basins are born on Earth; the valley that makes a place for the ocean is called a rift valley. Pieces of lithosphere, rifted away from Africa and elsewhere, have journeyed across the Earth's surface and joined with the edge of Europe. These pieces of lithosphere lie under southern England, Germany, France, and Greece, among other places.

When a continent-sized "layer cake" of rock is pushed, the upper layers move more readily than the lower layers. The upper layers of rock are heavy but easier to move than those beneath it (much like a full filing cabinet is heavy but, when pushed, moves more easily than the floor beneath it). Between near surface rocks and the deeper, more ancient crustal rocks, a flat-lying fault forms, also called a detachment fault. This horizontal crack, called a thrust fault, contains fluid (water, mostly). The same hydraulic force that makes hydraulic machines lift huge weights functions in this crack as well. The fluid is so nearly incompressible that a sizeable piece of a continent can slide on it when pushed. The fault block floats on fluid pressure between the upper and lower sections of the lithosphere like a fully loaded tractor trailer gliding effortlessly along a rain-slicked road. The mountains that are heaved up where the thrust fault reaches the surface are one kind of fault block mountains. Both the Jura Mountains and the Carpathians are fault block mountains.

Europe was not formed in one piece, or at one time. Various parts of it were formed all over the ancient world, over a period of four billion years, and were slowly brought together and assembled into one continent by the processes of plate tectonics. What is now called Europe began to form more than 3 billion years ago, during the Archean Eon.

Most geologists feel that prior to and during the creation of the oldest parts of Europe, Earth only superficially resembled the planet we live on today. Active volcanos and rifts abounded. The planet had cooled enough to have a solid crust and oceans of liquid water. 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 earth's most ancient crustal rocks, moved across the surface of a frantic crazy-quilt planet. Whatever it truly was like, the oldest regions in Europe were formed in this remote world. These regions are in Finland, Norway (Lofoten Islands), Scotland, Russia, and Bulgaria.

The piece of Europe that has been in its present form for the longest time is the lithospheric crust underneath Scandinavia, the Baltic states, and parts of Russia, Belarus, and Ukraine. This region moved around independently for a long time, and is referred to as Baltica. It is the continental core, or craton , to which other parts were attached to form Europe.

At the opening of the Mesozoic Era , 245 million years ago, a sizeable part of western and southern Europe was squeezed up into the Central Pangean mountain system that sutured Laurasia and Gondwana together. Pangea was the huge landmass from which all continents drifted; Laurasia and Gondwana were the two supercontinents that Pangea separated into about 200 million years ago. Europe was almost completely landlocked, its southern regions part of a mountain chain that stretched from Kazakhstan to the west coast of North America .

The birth of a new ocean basin, the Atlantic, signaled the end of Pangea. The Central Pangean Mountains, after tens of millions of years, had worn down to sea level and below. A new ocean basin, not the Mediterranean, but rather the Ligurean Ocean, began to open up between Africa and Europe. This formed a seaway between the modern North Atlantic and the Neo-Tethys Ocean (which no longer exists). Sea water began to leave deposits where high mountains had stood, and a layer cake of sediment—laid down on the shallow sea bottom—began to accumulate throughout Europe.

Beginning at the close of the Mesozoic Era (66 million years ago), and continuing through the Cenozoic Era to the present day, a complex orogeny (mountain building) has taken place in Europe. The ocean basin of Tethys was entirely destroyed, or if remnants still exist, they are indistinguishable from the ocean crust of the Mediterranean Sea. Africa has shifted from west of Europe (and up against the United States' East Coast) to directly south of Europe, and their respective tectonic plates are now colliding.

As in the collision that made the Variscan mountain belt, a couple of dozen little blocks are being pushed side-ways into southern Europe. The tectonic arrangement can be compared with a traffic jam in Rome or Paris, where numerous moving objects attempt to wedge into a space in which they cannot all fit.

When sea level fell below the level of the Straits of Gibraltar around six million years ago, the western seawater passage from the Atlantic Ocean to the Mediterranean Sea closed, and water ceased to flow through this passage. At about the same time, northward-moving Arabia closed the eastern ocean passage out of the Mediterranean Sea and the completely landlocked ocean basin began to dry up. Not once, but perhaps as many as 30 times, all the water in the ancestral Mediterranean, Black, and Caspian Seas completely evaporated, leaving a thick crust of crystallized sea minerals such as gypsum , sylvite, and halite (salt). It must have been a lifeless place, filled with dense, hot air like modern below-sea-level deserts such as Death Valley and the coast of the Dead Sea. The rivers of Europe, Asia , and Africa carved deep valleys in their respective continental slopes as they dropped down to disappear into the burning salt wasteland.

Many times, too, the entire basin flooded with water. A rise in global sea level would lift water from the Atlantic Ocean over the barrier mountains at Gibraltar. Then the waters of the Atlantic Ocean would cascade 2.4 mi (4 km) down the mountainside into the western Mediterranean basin. From Gibraltar to central Asia, the bone-dry basin filled catastrophically in a geological instant—a few hundred years. This "instant ocean" laid deep-sea sediment directly on top of the layers of salt. The widespread extent and repetition of this series of salt and deep-sea sediment layers is the basis for the theory of numerous catastrophic floods in the Mediterranean basin.

For reasons not yet fully understood, Earth periodically experiences episodes of planet-wide climatic cooling, the most recent of which is known as the Pleistocene Epoch . Large areas of the land and seas become covered with ice sheets thousands of feet thick that remain unmelted for thousands or hundreds of thousands of years. Since the end of the last ice age about 8,000–12,000 years ago, only Greenland and Antarctica remain covered with continent-sized glaciers . But during the last two million years, Europe's northern regions and its mountain ranges were ground and polished by masses of water frozen into miles-thick continental glaciers.

Ice in glaciers is not frozen in the sense of being motionless. It is in constant motion—imperceptibly slow, but irresistible. Glaciers subject the earth materials beneath them to the most intense kind of scraping and scouring. An alpine glacier has the power to tear bedrock apart and move the shattered pieces miles away. These are the forces that shaped the sharp mountain peaks and u-shaped mountain valleys of modern Europe. Many European mountain ranges bear obvious scars from alpine glaciation , and the flat areas of the continent show the features of a formerly glaciated plain.

Humans have lived in Europe for much of the Pleistocene Epoch and the entire Holocene Epoch (beginning at the end of the last ice age, about 10,000 years ago). During the past few thousand years, humans have been significantly altering the European landscape. Wetlands across Europe have been drained for agricultural use from the Bronze Age onward. The Netherlands is famous for its polders, below-sea-level lands made by holding back the sea with dikes. Entire volcanoes (cinder cones) have been excavated to produce frost-resistant road fill.

The northwest fringe of Europe is made up of the two very old islands, Great Britain and Ireland, and numerous smaller islands associated with them. Geologically, these islands are a part of the European continent, although culturally separate from it. Unlike many islands of comparable size, the British Isles do not result from a single group of related tectonic events. They are as complex as continents themselves, which in the last two centuries has provided plenty of subject matter for the new science of geology .

Scotland and Ireland are each made of three or four slices of continental crust. These slices came together around 400 million years ago like a deck of cards being put back together after shuffling.

The Iberian Peninsula, occupied today by Portugal and Spain, is one of the pieces of lithosphere that was welded to Europe during the Variscan mountain-building event. Like Britain, it is an unusual "micro-continent" with a complex geologic history.

Since the Paleozoic Era , southern Europe has continued to acquire a jumbled mass of continental fragments from Africa. Even today, the rocks of Europe from the Carpathian Mountains southwestward to the Adriatic and Italy are made up of "tectonic driftwood," and are not resting on the type of solid, crystalline basement that underlies Scandinavia and Ukraine.

Since the late Mesozoic Era, the widening Atlantic Ocean has been pushing Africa counterclockwise. All the blocks of lithosphere between Africa and Europe, including parts of the Mediterranean seafloor, will in all likelihood eventually become a part of Europe.

The Alps resulted from Europe's southern border being pushed by the northern edge of Africa. In Central Europe, freshly-made sedimentary rocks of early Mesozoic age, along with the older, metamorphosed, Variscan rocks below, were pushed into the continent until they had no other way to go but up. Following the path of least resistance, these rocks were shaped by powerful forces into complex folds called nappes, which means tablecloth in French. The highly deformed rocks in these mountains were later carved into jagged peaks by glaciers during the Pleistocene Epoch.

The Jura Mountains, the Carpathians, and the Transylvanian Alps are made of stacks of flat-lying sedimentary rock layers. These mountain ranges were thrust forward in giant sheets out in front of the rising Alps.

A complex story of tectonic movement is recorded in the sea-floor rocks of the western Mediterranean. Corsica, Sardinia, Iberia, and two pieces of Africa called the "Kabylies"—formerly parts of Europe—moved in various directions at various speeds throughout the Cenozoic Era.

On the western Mediterranean floor, new oceanic lithosphere was created. Asubduction zone formed as an oceanic plate to the east sank below the western Mediterranean floor. The magma generated by this event gave rise to the Appenine Mountains, which formed as an island arc on the eastern edge of the western Mediterranean oceanic plate. The Appenines began to rotate counterclockwise into their present position. The Tyrrhenian Sea formed as the crust stretched behind this forward-moving island arc. In the Balkans, blocks of lithosphere have piled into each other over tens of millions of years.

The Dinarides and Hellenides, mountains that run down the east coast of the Adriatic Sea, form the scar left after an old ocean basin closed. The compressed and deformed rocks in these mountain ranges contain pieces of ocean floor. Just east of these seacoast mountains is a clearly-recognized plate boundary, where the European and African plates meet. The boundary runs from the Pannonian Basin (in Hungary, Romania, and Yugoslavia), cuts the territory of the former Yugoslavia in half, and winds up in Greece's Attica, near Athens.

Further inland, the Pannonian Basin results from the lithosphere being stretched as the Carpathian Mountains move eastward and northward.

The Aegean Sea seems to have formed as continental crust has been stretched in an east-west direction. It is a submerged basin-and-range province, such as in the western United States. The Pelagonian Massif, a body of igneous and metamorphic rock that lies under Attica, Euboea, and Mount Olympus, forms part of the Aegean sea floor. The Rhodopian Massif, in northern Greece, Bulgaria, and Macedonia, also extends beneath the Aegean Sea. Faults divide the ridges from the troughs that lie between them. The faults indicate that the troughs have dropped into the crust between the high ridges.

The Balkan Range in Bulgaria is thought to mark the crumpled edge of the European craton—the Proterozoic-age rocks extending north into Russia.

Europe is also host to isolated volcanoes related to structural troughs within the continent. The Rhine River flows in a trough known as the Rhine Graben. Geologists believe the Rhine once flowed southward to join the Rhone River in France, but was diverted by upwarping of the crust around the Vogelsberg Volcano. The Rhine then changed its course, flowing out to meet England's Thames River in the low-sea-level Ice Age.

Europe continues to change today. From the Atlantic coast of Iberia to the Caucasus, Europe's southern border is geologically active, and will remain so effectively forever, from a human frame of reference. Africa, Arabia, and the Iranian Plateau all continue to move northward, which will insure continued mountain-building in southern Europe.

Geologists are concerned about volcanic hazards, particularly under the Bay of Naples and in the Caucasus. In historic times, in the Aegean Sea and at Pompeii, Herculaneum, and Lisbon, entire cities have been devastated or destroyed by volcanoes, earthquakes, and seismic sea waves. These larger-scale natural disasters can and will continue to happen in Europe on an unpredictable schedule with predictable results.

See also Continental drift theory; Earth (planet); Historical geology

Europe

Europe is the world's sixth largest continent. Together with its adjacent islands, it occupies an area of about 4,000,000 square miles (10,360,000 square kilometers), roughly 8 percent of the world's land area. Geographically, Europe can be seen as a peninsula of the single great continent called Eurasia (Europe and Asia combined). However, because Europe has such a distinctive history and culture, it is considered a separate continent.

The boundaries of the European continent are recognized as the Ural Mountains and the Ural River in the east; the Caspian Sea and the Caucasus Mountains in the southeast; and the Black Sea and the Bosporus and Dardenelle Straits in the south. The Mediterranean Sea and the Strait of Gibraltar separate Europe from the African continent, while the Atlantic Ocean borders it in the west and the Arctic Ocean borders it in the north. Numerous islands around the continental landmass are considered to be a part of Europe. More than 40 independent counties lie within the boundaries of the European continent.

The highest point on the continent is Mount Elbrus in the Caucasus Mountains, which rises 18,481 feet (5,633 meters) above sea level. The lowest point occurs at the surface of the Caspian Sea, 92 feet (28 meters) below sea level.

Chief rivers and lakes

Europe's longest river is the Volga, which runs for almost 2,300 miles (3,700 kilometers) in central and western Russia before emptying into the Caspian Sea. It drains an area of about 533,000 square miles (1,380,470 square kilometers). Europe's second longest river, the Danube, runs through the heart of the continent. About 1,770 miles (2,850 kilometers) long, it drains an area of roughly 320,000 square miles (828,800 square kilometers). A third prominent river is the Rhine, which winds through west-central Europe for 820 miles (1,320 kilometers) before emptying into the North Sea. Other chief European rivers include the Elbe in central Europe; the Dnieper and Don in Russia; the Garonne, Loire, and Rhône in France; the Tagus in Spain; and the Oder and Vistula in Poland.

The Caspian Sea, with an area of 143,550 square miles (371,795 square kilometers), is the largest inland body of water in the world. The largest lake within the boundaries of Europe proper is Russia's Lake Ladoga, which covers approximately 7,000 square miles (18,100 square kilometers). Other large European lakes include Geneva and Zurich in Switzerland; Constance on the border of Switzerland, Germany, and Austria; Balaton in Hungary; Como, Garda, and Maggiore in Italy; and Vättern and Vänern in Sweden.

Major physical regions

Europe may be divided geographically into four physical regions: the Northwestern Uplands, the Central Plain, the Central Uplands, and the Alpine mountain chain.

Words to Know

Bedrock: Solid rock lying beneath the soil on the surface of Earth.

Bog: Area of wet, spongy ground consisting of decayed plant matter.

Fjord: Long, narrow, steep-sided inlet of the sea.

Glacier: Large mass of ice slowly moving over a mountain or through a valley.

Moor: Broad stretch of open land, often with boggy areas.

Moraine: Mass of boulders, stones, and other rock debris carried along and deposited by a glacier.

Northwestern Uplands. Uplands—high plateaus, rugged mountains, and deep valleys—stretch along Europe's northwest coast from western France through the United Kingdom to the Scandinavian peninsula. Farming in this area is often difficult because of the rocky soil, and the climate is often rainy. Moors and bogs (areas of wet spongy ground) dominate in the northern sections.

During the last Ice Age, which ended about 11,000 years ago, glacial ice covered much of the far northern areas. When the ice retreated, it left deep valleys along the shores into which ocean water flowed. These narrow arms of the sea—called fjords—reach far inland and are bordered by steep mountains.

Central Plain. The most densely settled part of Europe, with its largest cities and manufacturing sites, is the Central Plain. Starting at the Atlantic coast of France, it spreads out in a V-shape, growing wider as it extends west. At the Ural Mountains, it stretches from the Arctic Ocean to the Black Sea. Except for being perfectly flat in the Netherlands, the plain features occasional hills and isolated ridges. Much of the plain holds fertile agricultural soil.

Around the Baltic Sea, Ice Age glaciers left mounds of boulders, stones, and other rock debris they had carried along. These remaining hills, called terminal moraines, mark the leading edge of these glaciers.

Glaciers subject earth materials beneath them to the most intense kind of scraping and scouring. An alpine glacier has the power to tear bedrock (solid rock beneath soil) apart and move the shattered pieces miles away. These are the forces that shaped the sharp mountain peaks and U-shaped mountain valleys of modern Europe. Many European mountain ranges bear obvious scars from alpine glaciation, and the flat areas of the continent show the features of a formerly glaciated plain.

Central Uplands. Between the Central Plain and the Alpine mountains lies a band of uplands. It stretches from Spain's Atlantic coast through France and Germany to Poland. Important mountainous and wooded plateaus in this band include the Meseta (in Spain), the Massif Central (in France), the Ardennes (across Belgium, Luxembourg, and France), the Black Forest (in Germany), and the Bohemian Forest (along the northern Czech-German border).

Alpine mountain chain. Southern Europe from Spain to the southern part of western Russia is dominated by the Alpine mountain chain. Beginning at the western edge, the mountains forming this chain are the Sierra Nevada range in Spain, the Pyrenees between Spain and France, the Alps in south-central Europe, and the Apennines in Italy.

The Sierra Nevada range in southern Spain runs parallel to the Mediterranean Sea for about 60 miles (100 kilometers). The highest peak in the range is Mulhacén, which rises to a height of 11,411 feet (3,478 meters).

The Pyrenees form an effective barrier between the Iberian Peninsula (on which Portugal and Spain lie) and the rest of Europe. They extend 270 miles (435 kilometers) in an almost straight line from the Bay of Biscay on the west to the Gulf of Lions on the east. The highest peak in the Pyrenees is Pico de Aneto, 11,168 feet (3,404 meters) above sea level.

The Alps are Europe's great mountain system. They stretch in an arc for almost 660 miles (1,060 kilometers) from the Mediterranean coast between France and Italy into Switzerland and along the northern boundary of Italy, through southwest Austria, before ending in Slovenia. The Alps, composed of more than 15 principal mountain ranges (all of which have offshoot ranges), cover an estimated 80,000 square miles (207,200 square kilometers). They form a barrier between southern Europe and western and central Europe. The highest peak in the Alps is Mont Blanc, 15,771 feet (4,807 meters) in height. Many peaks in the Alps rise above the snowline, 8,000 to 10,000 feet (2,440 to 3,050 meters), and thus are permanently snowcapped.

The Apennines run the entire length of the Italian peninsula. They extend about 840 miles (1,350 kilometers) from the Ligurian Alps (which they resemble geologically) in northwest Italy south to the Strait of Messina. The highest peak in the Apennines is Monte Corno, which stands 9,560 feet (2,914 meters) above sea level. Most rivers in Italy find their source in the Apennines. The central and southern portions of the

mountain system are marked by crater lakes and volcanoes. Two of those volcanoes—Vesuvius and Etna—are still active. It was Vesuvius that erupted on August 24, a.d. 79, burying the cities of Pompeii and Herculaneum.

Boundary mountains

The Caucasus Mountains, extending for about 750 miles (1,210 kilometers), act as a divide between Europe and the Middle East. The mountain system is volcanic in origin, and many of its peaks rise above 15,000 feet (4,600 kilometers). Included in this group is Mount Elbrus, Europe's highest mountain. Lying northeast of the Caucasus are the Ural Mountains, the far eastern boundary of Europe. Unlike the Caucasus, the Urals do not form an almost impassable wall. They are low and covered with forests. The Urals, extending about 1,500 miles (2,400 kilometers) from the Arctic tundra to the deserts near the Caspian Sea, average only 3,000 to 4,000 feet (900 to 1,200 meters) in height. The highest peak in the range is Mount Narodnaya, which rises 6,214 feet (1,894 meters) above sea level.

Geological forces in present-day Europe

Europe continues to change today. From the Atlantic coast of the Iberian Peninsula to the Caucasus, Europe's southern border is geologically active. It will remain so effectively forever. Africa, Arabia, and the Iranian Plateau all continue to move northward, which will insure continued mountain-building in southern Europe.

Geologists are concerned about volcanic hazards, particularly under the Bay of Naples and in the Caucasus. Smaller earthquakes, floods, and other natural disasters happen almost every year. In historic times, entire European cities have been devastated or destroyed by volcanos, earthquakes, and seismic sea waves. These larger-scale natural disasters can and will continue to happen in Europe on an unpredictable schedule.