(b. Houdreville, Meurtheet-Moselle, France, 9 March 1839; d. Malzéville, near Nancy, France, 22 July 1917)
Gtand’Eury studied first at the École Loritz in Nancy, which later became the École Professionnelle de l’Est. He then attended the École des Mines at St.-Éthnne, from which he graduated first in his class in 1859. Grand’Eury worked for several years as an engineer at the Roche-la-Moliêre mines, but being unable, for reasons of health, to spend prolonged periods in the mines, he then accepted a post as répétiteur at the École des Mines at St.-Étienne, where he later became professor of trigonometry. These were his only official positions (1863–1899). In 1885 the Institute named him a corresponding member.
Grand’Eury’s first work, on the carboniferous flora of the department of the Loire (1877), touched upon all the topics with which he was to be especially concerned—paleobotanical stratigraphy, the reconstruction of Paleozoic plants, their ecology, and the conditions of formation of coal seams. It also contained a map of the subterranean topography of the basin of the upper Loire and listed new genera and species of plants.
La formation des couches de houille du terrain houiller (géogénie), published in 1887, was the result not only of Grand’Eury’s researches in the Loire basin but also of his observations made during ten years of travel in northern Europe, Upper Silesia, and the Urals, and of his studies of the Gard basin. In this work Grand’Eury considered the coal strata, the coal’s relationship to the encasing rocks, and the deposition and formation of the coal beds. In 1910 he published a new basic work, La géologie et la paléonligie du bassin houiller du Gard, which contained many geological cross sections and columns, together with illustrations of fossil plants and underclays.
Two sections of a planned larger work, Recherches géobotaniques sur les forêts et sols fossils et sur la végétation de la flore houillére, were published before World War I. During the war Grand’Eury’s only son and collaborator, Maurice, was killed in action, and the books were never completed.
The study of plant impressions led Grand’Eury tO establish for the Massif Central a series of stages that he named for the most abundant representative plants: the cordaitean (lower portion of the St.-Étienne layer), the filicite (middle portion of the same layer), and the Calamodendron. He also used names of localities to designate other stages familiar to regional geologists.
His knowledge of the floral succession, applied to mine development, led Grand’Eury to advise the continuation of borings that had been stopped and, thus, to the discovery of new coal deposits. He also drew many scientific hypotheses from this work, notably some concerning the mutation of species.
The study of so many seeds excited Grand’Eury, and as early as 1875 he suspected that a great many of them that he found separately had come from Filicineen-type fronds. He did not describe Pecopteris pluckeneti, to which hundreds of tiny seeds are attached, until 1905—after the publications of Robert Kidston (1903) and Oliver and Dukinfield Scott (1904), which were also devoted to seeds in connection with fronds. He concluded that the vegetative organs were comparatively less variable than the reproductive organs, in other words, that a particular foliage will remain constant in the course of evolution but will have different seeds attributed to it.
Grand’Eury was convinced of the necessity of using special generic names for the various organs of a plant. He originated the terms Cordaianthus for the inflorescence of the Cordaianthus for the axis, Cordaifloyos for the bark, and Cordaixylon for certain woods. His reconstructions of Lepidodendra, of Cordaites, and of other plants from isolated remains of leaves, trunks, and seeds were scientific masterpieces that are still discussed in works on paleobotany.
The observation of mixtures of plant remains— particularly of various fossil rhizomes and roots in situ—and detailed surveys of the sections he investigated enabled Grand’Eury to reconstruct the vegetation, to identify both plants living in almost unmixed populations and social plants, and to establish certain conditions of growth.
Grand’Eury was active in the discussion of the deposition of coal. After having been convinced of allochthony, that is, origin by transport, he accepted the concept of deposition at the bottom of large marshy lakes. He stated that one always returned to the idea of a swamp, even if there is only a faint resemblance between coal and peat, in terms of the manner of accumulation of plant debris. The formation took place not on the spot but a short distance away. He also accepted, for certain basins, the existence of a cover of deep water surrounded by large, wooded marshes but held that a uniform conclusion for all basins was not possible. Grand’Eury clearly spoke of a subsidence of the ground necessary for the formation of a coal bed. In the marshy basins such as those he studied, he paid special attention to the schistification of coal, which is due to a water current’s carrying sediments that mix with carbonaceous material.
I. Original Works. Grand’Eury’s writings include “Mémoire sur la flore carbonifére du département de la Loire et du centre de la France étudiée aux trois points de vue botanique, stratigraphique et géognostique,” in Mémoires de l’Académie des sciences de l’Institut de France. 24 , no. I (1877), 1–624; “La formation des couches de houille du terrain houiller (géogénie),” in Mémories de la Société géologique de France, 3rd ser., 4 (1887), 109–196; La géologie et la paléontologie du bassin houiller du Gard (St. Étienne, 1890); and Recherches géobotaniques sur les foreêts et sols fossils et sur la végétation de la florê houillère 3 vols. (Paris-Liêge. 1912–1914).
II. Secondary Literature. See Paul Bertrand, “C. Grand’Eury. Notice nécrologique.” in Bulletin de la Société géologique de France, 4th ser., 19 (1920), 148–162; H. Guyot, “Notes sur le paléobotaniste lorrain Cyrille Grand’Eury,” in Bulletin de la Société d’histoire naturelle de Metz, 3rd ser., 10 (1935), 317–324; and Paul Vuillemin. “L’oeuvre de Cyrille Grand’Eury,” in Revue générale des science pures et appliquées, 28 (1917), 601–604.