Guettard, Jean-Étienne
Guettard, Jean-Étienne
(b. Étampes, Seineet-Oise, France, 22 September 1715; d Paris, France, 6 January 1786)
geology, natural history, botany.
A versatile scientist trained in medicine and chemistry, Guettard gradually acquired knowledge of the various branches of natural history. Although always concerned to some degree with all these fields, most of his career, especially after about 1746, was devoted to geology, and his reputation now rests upon two achievements: his discovery of the volcanic nature of Auvergne, and his attempt to construct a geological map of France.
Guettard’s schooling in Étampes, nearby Montargis, and Paris was less important in shaping his career than was the influence of his maternal grandfather, François Descurain, a physician and apothecary in Étampes, as well as an amateur botanist and friend of Bernard de Jussieu. Guettard’s early activities followed the pattern set by Descurain. While studying in Paris, he was introduced, probably by Jussieu, to naturalist-physicist René Antoine Ferchault de Réaumur and by 1741 had become curator of Réaumur’s natural history collection. As Réaumur’s assistant, he also conducted experiments on the regeneration of marine polyps. In 1742 he was admitted to the Faculté de Médecine de Paris, and on 3 July 1743 was elected to the Académie Royale des Sciences as an adjoint botaniste. At the same time he began to take field trips in the Loire Valley and in Normandy and to form his own natural history collection. His first major publication, Observations sur les plantes (1747), was a botanical study of the environs of Étampes, based upon a manuscript by his grandfather.
By 1747 Guettard had become médecin botaniste to Louis, duc d’Orléans, the two men having in common not only their religious views—both were devout Jansenists—but also their interest in the chemical analysis of minerals and rocks. After the duke’s death in 1752, his son, Louis-Philippe, continued to support Guettard and he was given rooms in the Palais-Royal. With a laboratory at his disposal and an assured income, Guettard was free to devote himself entirely to scientific research. The remainder of his career is remarkable for his many long field trips, the development of a large scientific correspondence, and the publication of numerous articles often of the length and character of small monographs.
All of Guettard’s scientific work bears the stamp of the Baconian naturalist who consciously avoided the formulation of theories. He attacked the ideas of the natural theologians, the cosmology and geology of Buffon, and the biology of Charles Bonnet, labeling all such systems premature, scientifically unsound, or philosophically dangerous and tending toward materialism. Although his own work is not free of preconceptions, Guettard tried to avoid drawing conclusions from his data. Thus, while his studies of sedimentation and erosion provided the kind of evidence other geologists were using to suggest an extension of the time scale beyond the biblical 6,000 years, Guettard’s own writings contain no hint of such ideas. Similarly, his studies of the comparative anatomy of fossil and living forms led him only to deny repeatedly the likelihood that species can become extinct. It was therefore left to his contemporaries and successors to recognize the implications of Guettard’s work.
Most of Guettard’s field trips within France—he also traveled in the Low Countries, Italy, Switzerland, and Poland—were undertaken to supply data for a national geological survey and are thus of relatively small intrinsic interest apart from the larger project. A notable exception was his voyage to Auvergne in 1751, accompanied by his friend Chrétien-Guillaume de Lamoignon de Malesherbes. During this journey Guettard noticed that volcanic rocks were often used in the construction of local roads and dwellings; he examined the quarries and concluded that the whole region was volcanic. This discovery was announced in his “Mémoire sur quelques montagnes de la France qui ont été des volcans” (Mémories de l’Acadeémie royale des sciences pour l’année 1752 [1756], pp. 27–59). He did not pursue the subject further, but this memoir induced several of his contemporaries to study the geological history of Auvergne, and the region very soon became a tourist attraction. Years later the priority of Guettard’s discovery was challenged by Barthélemy Faujas de Saint-Fond in his Recherches sur les volcans éteints du Vivarais et du Velay (1778). Whether or not anyone had in fact anticipated Guettard, as Faujas claimed, it is certain that Guettard’s discovery was made independently and was the first public announcement.
In the well-known controversy over the nature of columnar basalt, Guettard at first supported the view that these formations were not volcanic in origin. However, after visits to Italy in 1771 and 1772 and the vicinity of Montpellier in 1771, he began to have doubts, and these doubts were confirmed when in 1775 he explored the neighborhood of Montélimar in Dauphiné. His change of opinion about the origin of columnar basalt was announced in his Mémoires sur la min éralogie du Dauphiné (1779).
Guettard’s work as a geological cartographer began before 1746, the year in which he presented what he called a preliminary “mineralogical map” of France to the Académie Royale des Sciences. His travels and reading had called his attention to “a certain regularity” in the distribution of minerals and rocks over the earth’s surface, and he decided to plot his data on a map. The result was his “Mémoire et carte minéralogique sur la nature & la situation des terreins qui traversent la France & I’Angleterre” (Mémories de l’Académie royale des sciences pour l’année 1746 [1751], pp. 363–392), which was followed in later years by memoirs and maps dealing with the Middle East, part of North America, Poland, and Switzerland, as well as preliminary (unpublished) maps of Italy and Corsica. These maps show, by means of conventional chemical symbols, the location of rock formations and mineral deposits, and they are also marked off in regions labeled Bandes. Each Bande was characterized by the predominance of certain deposits, so that in France, for example, he could outline three such concentric zones: the Sandy Band (primarily sand stones and limestones) with its center near Paris, the Marly Band, and the Schistose or Metalliferous Band. Although superposition was sometimes noted, the scheme was basically not a stratigraphic one. Guettard hoped eventually to clarify the relationships between the systems of bands outlined for neighboring geographical regions, and he also expected that his maps would enable scientists to find or predict the locations of useful or valuable mineral deposits, building materials, and agricultural and industrial soils. As late as 1784, he was still perfecting his initial mineralogical map of France.
In 1766 Guettard and Lavoisier were commissioned by Henri Bertin, minister and secretary of state in charge of mining, to prepare a geological survey of France. The collaboration of Guettard and Lavoisier had actually begun before that date, and among the several field trips they took together was their famous geological tour of Alsace, Lorraine, and Franchecomté in 1767. By 1777 they had completed sixteen quadrangles, while bringing an almost equal number to partial completion, out of a projected total of some 200 maps. The survey passed into the hands of Antoine Monnet in 1777, and he published thirty-one quadrangles in the Atlas et Description minéralogiques de la France (1780), which he later issued in a second edition containing forty-five quadrangles. The rest of the survey was never executed.
The maps of the Atlas feature the chemical symbols used by Guettard, but he intentionally omitted the system of bands so that the survey would not appear to be based on any one geological theory; in addition, Lavoisier used the margin of each quadrangle for a vertical section designed to show the stratigraphic arrangement of the earth’s crust. Monnet’s maps followed a somewhat similar pattern. Although employing chemical symbols on geological maps was popular for a time, the maps of the Atlas had no close imitators; contemporaries and later geologists, with the notable exception of Nicolas Desmarest, found these maps to be models of observational accuracy, but the cartographic techniques of Guettard and Lavoisier were superseded by those developed in subsequent decades by such men as A. G. Werner, William Smith, Georges Cuvier, and Alexandre Brongniart.
Among Guettard’s many other achievements were his identification of trilobites in the slates of Anjou and his discovery in France of sources of kaolin and petuntse needed in the manufacture of good porcelain. As a botanist, he remained a defender of the Linnaean system against its many critics. When the Académie Royale des Sciences was reorganized in 1785, he became a pensionnaire in the division of botany and agriculture. Upon his death, his natural history collection and library of more than 3,500 titles were sold and their fate is uncertain. His unpublished papers include memoirs on subjects botanical and geological, the latter including studies of virtually every French province. Toward the end of his life, Guettard searched for funds to support the publication of these papers, but without success. The papers then passed into the hands of Lavoisier, Guettard’s scientific executor, whose efforts to have some of them published also failed.
BIBLIOGRAPHY
I. Original Works. Works by Guettard include Observations sur les plantes, 2 vols. (Paris, 1747); Mémoirés sur la minéalogie du Dauphiné, 2 vols. (Paris, 1779); Mémoirés sur différentes parties de la physique, de l’histoire naturelle; des sciences et des arts, &c., 5 vols. in 6 (Paris, 1768–1786). Guettard contributed to Atlas et Description minéralogiques de in France. Entrepris par ordre du Roi…Premiére Partie (Paris, 1780), in which the maps are the work of Guettard, Lavoisier, and Monnet, and the text the work of Monnet; for an analysis, see the Lavoisier bibliographies cited below.
Guettard also contributed to J. B. de La Borde, E. Béguiller, et al., Description générale et particulière de la France, 4 vols. (Paris, 1781–1784), continued as Voyage pittoresque de la France, 8 vols. (Paris, 1784–1800). He translated Pliny the Elder, Histoire naturelle, 12 vols. (Paris, 1771–1782), and published more than seventy articles in the Mémoirés de l’Académie roylae des sciences, with a few in Observations sur la physique, sur l’histoire naturelle et sur les arts and Journal oeconomique.
More than twenty-five cartons and volumes of Guettard’s MSS are in the Central Library of the Muséum National d’Histoire Naturelle, Paris Travel journals and other documents are in the archives of the Académie des Sciences, Paris, and the Olin Library, Cornell University, Ithaca, New York. One journal has been published, with minor modifications, by A. Verniére, “Note sur les environs de Vichy et sur la découverte des volcans éteints de l’Auvergne (d’aprés un manuscrit autographe de Guettard, 1751),” in Revue scientifique du Bourbonnais et du centre de la France, 14 (1901), 5–13. Additional letters are in the Municipal Library of Clermont-Ferrand, Puy-de-Dôme, and can be found among the papers of Pierre-Michel Hennin, Library of the Institut de France, Paris. Single letters of importance are published in Buffon, Les époques de la nature, Jacques Roger, ed., Mémoirés du Muséum National d’ Histoire Naturelle, ser. C, 10 (Paris, 1962), cxxxix, n. 7; and René Fric, “Une lettre de Guettard á Monner au sujet des prismes basaltiques,” in Bulletin historique et scientifique de l’Auvergme, 78 (1958), 91–96.
II. Secondary Literature. For works on Guettard see Aimé de Soland, “Étude sur Guettard,” in Annales de la Société linnéenne de Maine-et-Loireé, 13, 14, 15 (1871–1873), 32–88; Gavin de Beer, “The Volcanoes of Auvergne,” in Annals of Science, 18 (1962), 49–61; M. J. A. N. C. Condorcet, “Éloge de M. Guettard,” in Histoire de l’Académie royale des sciences pour l’année 1786 (1788), pp. 47–62; Denis I. Duveen and Herbert S. Klickstein, A Bibliography of the Works of Antoine Laurent Lavoisier 1743–1794 (London, 1954); Denis I. Duveen, Supplement to a Bibliography of the Works of Antoine Laurent Lavoisier 1743–1794 (London, 1965); Roland Lamontagne, “La participation canadienne á l’oeuvre minéralogique de Guettard, “in Revue d’histoire des sciences et de leur applications, 18 (1965), 385–388; A.-L. Letacq, “Notice sur les travaux scientifiques de Guettard aux environs d’Alençon & de Laigle (Orne),” in Bulletin de la Société linnéenne de Normandie, 5 (1891), 67–85; R. Michel, “À propos de le découverte des Volcans éteints de l’Auvergne et du Vivarais: Notes sur deux géologues du XVIIIe siècle, Guettard (1715–1786) et Faujas de Saint-Fond (1741–1819),” Revue des sciences naturelles d’Auvergne, 11 (1945), 37–53; and R. Rappaport, “The Geological Atlas of Guettard, Lavoisier, and Monnet: Conflicting Views of the Nature of Geology,” in Cecil J. Schneer, ed., Toward a History of Geology (Cambridge, Mass., 1969).
Rhoda Rappaport