Jules Marcou (1824-1898) trained first as a mathematician but in his early twenties transferred his interest and talents to geology. His natural talents came to the attention of Louis Agassiz and others, and in 1845—at the age of 21 or 22—he published his first work in the field. Already by 1846 he assumed the chair of Professor of Mineralogy at the Sorbonne, but soon vacated the post to take on the position of “Traveling Geologist” of the Jardin des Plantes. He chose the United States as his field of inquiry, and in 1848 made and expedition to Lake Superior with Agassiz. He spent much of the rest of his life in this country, traveling widely and publishing prolifically. Among other expeditions, he accompanied Lieutenant Whipple on his survey of a southern route for the Transcontinental Railroad (1853) and Lieutenant Wheeler on his survey of Southern California (1875). His findings appeared in the official reports of both expeditions. In the Spring of 1898 he died of pneumonia in Cambridge, Mass.
Marcou’s Geological Map of the United States depicts the country west to the Rocky Mountains, with surface strata color-coded according to a legend at right. In the left and upper margins are geological sections from Lake St. John in Quebec to Mobile, Alabama and from Yorktown, Virginia to Fort Laramie, Wyoming. The map was published at the same time as a 92-page explanatory text bearing the same title, not present here.
For its time the map was extremely ambitious, by far the most detailed geological map of the country to date, and one of the first to treat strata as far west as the Rockies. Its compilation involved an enormous amount of effort on Marcou’s part:
“my object has been to recapitulate, very concisely, the numerous observations of the geologists who have studied America, and to present, as completely as possible, the results which have been attained in the study of its geological formations. Perhaps this task is beyond my ability. Nevertheless, I have carefully studied all the published documents, and even manuscript ones, which I have been able to procure, that relate to the subject; and I have travelled for three years in various parts of America, to verify the descriptions and geological maps that have been published. Many of the American geologists have assisted me in these researches” (Geological Map of the United States, p. 17)
In the 1830s Roderick Murchison had conducted his studies in Wales and on the Continent and developed stratigraphic systems for the Siluraian and Devonian periods, which Edouard de Verneuil then applied to his study of the geology of the United Stats. Per Marcou, his map’s major contribution was to unify its nomenclature with the latest geological developments in Europe: It was “the first [of the United States] which gives the distribution of the strata, according to the nomenclature of Murchison and de Verneuil, into lower and upper Silurian and Devonian; it also extends beyond the Mississippi as far as the Rocky Mountains.” (Mapoteca Geologica Americana)
“By adopting these divisions, the geological map of America can be compared with that of England, published by Murchison; with that of Germany, by Murchison, De Verneuil and D’Archiac; with that of Russia and Scandinavia, by Murchison and De Verneuil; and, finally, with that of Bohemia, published by Barrande.” (Geological Map of the United States, p. 16)
I am wholly incompetent to judge the merits of Marcou’s map, but it, and successive editions of 1855, 1858 and 1872 published here and abroad, all engendered criticism and controversy:
“This attempt on the part of Marcou was certainly commendable, requiring courage as well as judgment. Unfortunately, Marcou does not seem to have used discretion in all cases in the selection of his authorities, and made altogether too sweeping generalizations, often in direct contradiction of facts made known by other workers.” (Merrill, p. 449)
“The points at issue were matters of stratigraphic identification. Marcou was criticized for identifying large portions of the United States as belonging to the Jurassic and Triassic periods, rather than the conventional Cretaceous classification. The matter was made even less agreeable by Marcou’s retention of important fossil evidence which belonged to the government; and upon its ultimate return, it was plain that these materials were of European rather than American Jurassic origin. Marcou had identified large portions of the continent as belonging to a period younger than the Jurassic, and, in the view of [some prominent American geologists], all such analyses had been done without benefit of field experience and were of little service to American geology.” (Lurie)
Though I find numerous institutional holdings of the map, it is very scarce in trade. In all, an impressive and most interesting map, evidence of the internationalization of geological research in the mid-19th century and the consequent rapid advance of American geology.
Marcou and Marcou, Mapoteca Geologica Americana, #40. OCLC 1672914, giving many institutional holdings. Not in Phillips, Maps of America or Rumsey. Sabin #44502, mentioning the volume only.
Background from Alpheus Hyatt, “Jules Marcou”, Proceedings of the American Academy of Arts and Sciences, vol. 34 no. 23 (June 1899), pp. 651-56; Edward Lurie, “Marcou, Jules” at Encyclopedia.com; and George P. Merrill, “Contributions to the History of American Geology”, in Annual Report of the Board of Regents of the Smithsonian Institution… Year Ending June 30, 1904, pp. 448-452.