(b. Soulaines-Dhuys, France, 16 September 1725; d. Paris, France, 28 September 1815)
Desmarest was the only child of Jean Desmarest, the local schoolteacher, and Marguerite Clement. Practically nothing is known about his youth until 1740, when his father died. In February 1741 Desmarest’s mother remarried, and Nicolas, now in the care of a guardian, was placed in the Oratorian collège of Troyes. Here he received a sound education, and when he left Troyes for Paris in late 1746 or early 1747, he embarked upon a scientific career that brought him membership in the Academy of Sciences in 1771. His election to that body followed the scientific work with which his name has remained principally associated: his assertion that the basalt columns found in Auvergne and elsewhere are volcanic in origin. The election to the Academy of Sciences crowned with success what had been an often frustrating campaign for membership, begun as early as 1757.
But Desmarest’s profession was not exclusively scientific; much of his energy during his best years was consumed by his duties in the government bureaucracy controlling industry, which culminated in his serving as inspector general of manufactures. After the Revolution suppressed this post, Desmarest found himself working for a time in various minor government agencies and was appointed as a teacher in the écoles centrales. He married Françoise Tessier, twenty-five years his junior, on an unknown date. They had a son in 1784, and Desmarest’s wife died in 1806.
Despite Desmarest’s fame for identifying basalt as volcanic, his general geological orientation was by no means solely volcanological. To the extent that he professed any geological doctrine, it reflected the influence of Guillaume-François Rouelle, whose public courses he had attended in Paris. Rouelle expounded a neptunist outlook regarding the origin of terrestrial formations, and in adopting Rouelle’s basic tenets Desmarest rejected forever the notion that volcanoes or an internal heat of the globe had been primarily responsible for producing the earth’s essential features. Thus, even though Desmarest greatly expanded the extent to which volcanoes were understood to have produced changes in the earth, he cannot be counted as a genuine volcanist; although he was in a sense the founder of the plutonist side of the basalt controversy, he did not represent the volcanists in the general dispute over modes of geological change that emerged from the confrontation of Wernerian and Huttonian theories of the earth. Indeed, Desmarest’s geology did not grow out of, and never became altogether adapted to, a “theory of the earth.” Instead, his scientific career developed out of the consideration of more narrowly circumscribed problems. His scientific demeanor always remained rather cautious, and in this regard he reflected a typical Enlightenment aversion to the liabilities of système.
After his arrival in Paris, Desmarest lived precariously for a time as a private tutor. His climb toward recognition in the learned world began in 1749, when he assisted Pierre-Nicolas Bonamy in editing the Suite de la clef, better known as the Journal de Verdun. In subsequent years he may have lived in part on fees for editing books; under his guidance there appeared a collection of the thoughts of the Abbé Louis Du Four de Longuerue (1754) and the seventh edition of Lesélémens de géométrie, by the renowned Oratorian teacher Bernard Lamy (1758). Of far more significance to Desmarest’s line of interest, however, was the French edition of Francis Hauksbee’s Physico-Mechanical Experiments (1754), which Desmarest edited and to which he added voluminous notes and remarks. In 1751 he won the prize competition of the Académie des Sciences, Belles-Lettres et Arts d’Amiens with an essay arguing that England had once been joined to France by an isthmus whose destruction was recent, natural, and noncatastrophic. The published essay (1753) was accompanied by maps and a cross section of the English Channel prepared by the geographer Philippe Buache; the maps, among the first to employ contour lines to show ocean depths, were used by Desmarest to show that the supposed isthmus still existed not far beneath the waves that had reduced it.
After his success in the Amiens competition, Desmarest continued to direct his attention to scientific questions concerning the earth’s surface and internal structure. In the 1754 Expériences physicoméchaniques, for example, he supported Hauksbee’s attack on a peculiar extension of the terraqueous globe doctrine, according to which the earth’s primitive formations had been deposited out of the terraqueous fluid in descending order of the specific gravity of the suspended materials. In 1756, just a few months after the Lisbon earthquake, he published an essay on the propagation of earthquake disturbances, presumed to be caused by the combustion of inflammable matter underground and conveyed by means of the worldwide network of interlocking mountain ranges. The seventh volume of the Encyclopédie (1757) brought forth two further contributions by Desmarest to his emerging specialty. “Fontaine” deals for the most part with the ancient problem of the origin of springs, or the manner in which rivers are fed and maintained. Desmarest supported the meteoric theory, claiming that rainfall is sufficient to account for the flow of rivers and that the earth can receive and store water in amounts large enough to account for the continued flow of springs. “Géographie physique” is a more general article outlining the aims and methods of investigating the earth’s surface features.
By the late 1750’s Desmarest had decided to concentrate on physical geography and the study of rocks, and in the course of several years he traveled extensively in France, observing the Paris region, Champagne, Burgundy, Lorraine, Alsace, Franche-Comté, Guienne, and Gascony. His notes from these travels in the late 1750’s and early 1760’s indicate a commitment to an organizing scheme like that of Rouelle, which called for a division of the earth’s surface features into three categories (ancienne, intermédiaire, nouvelle) corresponding respectively to a crystalline inner core, and two different sorts of sedimentary layers, all of them deriving from fluid sources.
In 1757 Desmarest began his most significant and extensive professional occupation outside of science. He was appointed by Daniel-Charles Trudaine, the intendant of finances and director of commerce, to make a study of the woolen cloth industry in France. For over three decades thereafter Desmarest was involved in the analysis and control of French industry as an agent of the royal government. He became expert in the technical aspects of numerous industries and developed special proficiency in papermaking technology. His treatises on the manufacture of paper made him a leader in the rationalization of paper technology in the late eighteenth century. As inspector of manufactures in the généralité of Limoges under the intendant Anne-Robert-Jacques Turgot, Desmarest devoted himself especially to agricultural matters. He later held the post of inspector of manufactures of the généralité of Châlons and ultimately served as inspector general, director of manufactures, for the entire realm (1788–1791).
It was in his capacity as an agent for Trudaine that Desmarest first traveled to Auvergne in 1763. While on a tour to examine industries south of Clermont-Ferrand, Desmarest noticed prismatic basalt columns in association with hardened lavas, such as had been described by Jean-Étienne Guettard after his 1751 visit to the region. Desmarest’s excitement at this discovery appears to have been stimulated initially as much by the mere appearance of the columns as by their possibly volcanic origin. At this time there was considerable interest in the finely sculptured basalts, especially in the articulated columns of County Antrim in Northern Ireland, the celebrated Giant’s Causeway. Evidently believing that the articulated columns of Auvergne were the first of that type known outside of Ireland, Desmarest momentarily let chauvinistic pride come to the fore but soon set about investigating the geological significance of the columns’ presence among lava flows.
Between 1764 and 1766 Desmarest and François Pasumot drew up a map of the main volcanic district of Auvergne, concentrating especially on the southern, Mont-Dore district. Their geological map was published with Desmarest’s first long memoir on the Auvergne basalts, which he delivered before the Academy of Sciences in 1771. This map did not fulfill Desmarest’s entire cartographic aim, however, and he continued to work intermittently on the Auvergne geological map for the rest of his life. A much larger and more detailed map than the 1771 version was finally published in 1823 by his son, Anselme-Gaëtan Desmarest.
Desmarest’s first public statement on the geological significance of the Auvergne basalts came in a paper he delivered to the Academy of Sciences in the summer of 1765, before departing on a year-long journey in Italy in the company of Duke Louis-Alexandre de La Rochefoucauld. The essential contents of this report are included in the sixth volume of plates for the Encyclopédie (1768). Here he argued that the presence of prismatic basalts infallibly indicates the former existence of volcanoes in that area. Hypothesizing that “the regular forms of basalt are a result of the uniform contraction undergone by the fused material as it cooled and congealed, shrinking around several centers of activity,” he promised a fuller explanation and substantiation of this supposition in a later work. This he never provided, however, and in his own time other voices were heard saying that a rapid, rather than slow, rate of cooling was responsible for the basalt’s columnar shape. But Desmarest’s attention had not been confined to basalts of prismatic form. Explaining that the basalts of Auvergne also take the form of ellipsoids composed of concentric layers and of large sheets broken into randomly oriented bundles of regular shape, he found himself leading the way to a study of the relation of these materials to their neighboring or enveloping matter.
The notion that prismatic basalts are a volcanic product, rather than rocks of igneous origin, was thus made known to the Academy of Sciences in 1765, and found its way into print in 1768. This opinion became prominent, however, only after 1771, when Desmarest delivered to the Academy of Sciences the lengthy report of his studies on the Auvergne basalts. This was followed by another memoir presented in 1775, and it is in these papers that Desmarest’s original contributions to geological science lie. Here he dealt with such problems as the origin of the matter constituting the basalts, the volcanic history of the Auvergne region, and the alterations that the volcanic flows had undergone.
Attempting to reconstruct a mental picture of the former condition of the lava flows whose extremities revealed prismatic basalts, Desmarest was led to a consideration of the destructive effects of flowing water upon the Auvergne terrain. He applied the idea of aqueous degradation, which had become fixed in his mind several years before his first visit in Auvergne, in such a way as virtually to enunciate a principle of uniformity in destructive geological processes. It is noteworthy that he at first took the principle of regularity in cause and rate of degradation as a necessary working hypothesis, but before long began to treat it as a result of his researches. Desmarest utilized his conclusions about Auvergne’s physiographical history to hazard a three-stage volcanic history of the region, thus extending historical geology into the field of volcanism.
Desmarest’s position on the nature of volcanoes always distinguished between the source of volcanic heat and the molten and solid ejecta. He consistently indicated that volcanoes feed on some combustible or fermenting agent and thus regarded lavas as material heated, as it were, accidentally. Basalt he took to be granite heated moderately—not to an extreme degree. This highly limiting view on the sources of volcanic action, not atypical of his time, naturally placed definite restraints on the possibility of his entertaining truly volcanist ideas, restraints which he always respected. His mature belief, expressed in Géographie physique, a large work produced in old age, was that burning beds of underground coal are the most likely cause of volcanic heat, and so he regarded volcanic action as a relatively recent interloper in geological history. Desmarest rejected Hutton’s assertion that volcanic heat might be a source of power sufficient to uplift continents. While suggesting that the earth’s age must be quite great, he never committed himself to a clear definition of the geological time scale. He retained a faith in the importance of certain catastrophic agencies of terrestrial change and did not regard this as inconsistent with his general adherence to uniformity in degradation.
I. Original Works. Desmarest made his scientific debut with Dissertation sur l’ancienne jonction de l’Angleterre à la France, qui a remporté le prix, au jugement de l’ Académie des sciences, belles-lettres arts d’Amiens, en l’année 1751 (Amiens, 1753), and followed this with Conjectures physicoméchaniques sur la propagation des secousses dans les tremblemens de terre, et sur la disposition des lieux qui en ont ressenti les effets (n.p., 1756). Vol. VII of Encyclopédie, ou dictionnaire raisonné des sciences, des arts et des métiers, par une société de gens de lettres (Paris, 1757) contains his “Fontaine,” pp. 80–101, and “Géographie physique,” pp.613–626. The first published statement of the volcanic origin of prismatic basalt is found in a brief commentary,“Planche VII. Basalte d’Auvergne,” in Recueil de planches, sur les sciences, les arts libéraux, et les arts méchaniques, avec leur explication, VI (Paris, 1768), pp. 3–4 of section entitled “Histoire naturelle. Règne minéral. Sixième collection. Volcans.” Desmarest’s detailed studies of the Auvergne basalts were published in three parts, the first two in “Mémoire sur l’origine & la nature du basalte à grandes colonnes polygones, déterminées par l’histoire naturelle de cette pierre, observée en Auvergne,” in Mémoires de l’Académie royale des sciences for 1771 (1774),705–775; and the third as “Mémoire sur le basalte. Troisième partie, où l’on traite du basalte des anciens; & où l’on expose l’histoire naturelle des différentes espèces de pierres auxquelles on a donné, en différens temps, le nom de basalte,” ibid., for 1773 (1777), 599–670. His general conclusions on the geological history of the Auvergne region were expressed in “Extrait d’un mémoire sur la détermination de quelques époques de la nature par les produits des volcans, & sur l’usage de ces époques dans l’étude des volcans,” in Observations sur la physique, sur l’histoire naturelle et sur les arts, 13 (1779), 115–126, expanded in “Mémoire sur la détermination de trois époques de la nature par les produits des volcans, et sur l’usage qu’on peut faire de ces époques dans l’étude des volcans,” in Mémoires de I’Institut des sciences, lettres et arts. Sciences mathématiques et physiques, 6 (1806), 219–289. Desmarest’s largest and most comprehensive geological work, which is largely derivative, is a part of the Encyclopédie méthodique, entitled Géographie physique, 5 vols. (Paris, an III (1794–1795]–1828), the last and posthumous volume edited in part by others.
Among the books edited by Desmarest, the most significant is Francis Hauksbee’s Expériences physico-méchaniques sur différens sujets, et principalement sur la lumière et l’électricité, produites par le frottement des corps, 2 vols. (Paris,1754).
Foremost among Desmarest’s writings in the fields of industry, manufacturing, and agriculture are his essays on papermaking methods: “Premier mémoire sur les principales manipulations qui sont en usage dans les papeteries de Hollande, avec l’explication physique des résultats de ces manipulations,” in Mémoires de l’Académie royale des sciences for 1771 (1774), 335–364; “Second mémoire sur la papeterie; Dans lequel, en continuant d’exposer la méthode hollandoise, l’on traite de la nature & des qualités des pâtes hollandoises & françoises; De la manière dont elles se comportent dans les procédés de la fabrication & des apprêts: Enfin des différens usages auxquels peuvent être propres les produits de ces pâtes,” ibid., for 1774 (1778), 599–687; “Papier. (Art de fabriquer le),” in Encyclopédie méthodique. Arts et métiers mécaniques, V (Paris-Liège,1788), 463–592; and Art de la papeterie (Paris, 1789).
The largest and most interesting collections of Desmarest’s correspondence are found in the Bibliothèque Nationale, Fonds Français, Nouvelles Acquisitions, MS 803 (letters exchanged by Desmarest and Pierre-Jean Grosley) and MS 10359 (letters from Turgot to Desmarest), and in the Bibliothèque Municipale de Beaune, MS 310 (letters from François Pasumot to Desmarest).
II. Secondary Literature. The single most important source of biographical information on Desmarest is a handwritten set of notes by his son, Anselme-Gaëtan Desmarest, “Notes et renseignements sur la vie et les ouvrages de mon père,” Bibliothèque de l’Institut de France, Fonds Cuvier, MS 3199. Georges Cuvier depended heavily upon them in preparing his “Éloge historique de Nicolas Desmarets [sic], lu le 16 mars 1818,” in Recueil des éloges historiques lus dans les séances publiques de l’Institut royal de France, II (Strasbourg-Paris, 1819), 339–374. Further references and discussion are found in Sir Archibald Geikie, The Founders of Geology, 2nd ed. (London-New York, 1905), pp. 140–175; and Kenneth L. Taylor, “Nicolas Desmarest and Geology in the Eighteenth Century,” in Cecil J. Schneer, ed., Toward a History of Geology (Cambridge, 1969), pp. 339–356.
Kenneth L. Taylor