Ruedemann, Rudolf

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(b. Georgenthal, Germany, 16 October 1864; d. Albany, New York, 18 June 1956)

paleontology, geology.

Ruedemann, America’s foremost graptolite specialist, was one of the three children of Albert and Franziska Seebach Ruedemann. The family was extremely poor (which may explain Ruedemann’s later frugality), but Ruedemann nevertheless was able to enroll in the University of Jena, where he studied mathematics with Gustav Steinmann and biology with Johannes Walther. He soon became interested in geology. His doctoral dissertation, Contact Metamorphose an der Reuth, was written in response to a problem in petrography assigned by Steinmann’s successor, Ernst Kalkowsky. Ruedemann received the degree magna cum laude in 1887; Kalkowsky had recommended that he be given a summa cum laude, but Ruedemann, in an early exhibition of the tactlessness that marked his career, unwisely opposed a favorite theory of his examining professor in chemistry. Haeckel, a friend of both, intervened to calm the antagonists.

From 1887 until 1892 Ruedemann had tenure at the University of Strasbourg. In the latter year he immigrated to the United States, where he first taught science in the high schools of Lowville and Dolgeville, New York. When John Mason Clarke succeeded James Hall as state paleontologist, however, he hired Ruedemann as his assistant, and Ruedemann began working at the New York State Museum in Albany in March 1899. Ruedemann himself succeeded Clarke as state paleontologist in 1925, and held this position until his retirement in 1937, although he continued to do research until 1942.

Ruedemann investigated the geology and paleontology of the principal valleys of New York, especially the Mohawk, where the Ordovician shales and limestones offered abundant and varied invertebrate fossils, many of which were previously undescribed. In particular, his interest was attracted by the enigmatic graptolites, which he began to study while he was teaching in Dolgeville. The material that he collected included complete growth series of Diplograptus—the first known for a graptolite (1897). Ruedemann was able to establish a graptolite zonation for the New York Ordovician black shales. These shales, older eastward, were replaced westward by shelf limestones. Graptolites increasingly became Ruedemann’s chief paleontological concern, and his monumental “Graptolites of North America,” published in 1947, marked the culmination of his career. He also attained an international reputation as a paleontologist through his researches on eurypterids (extinct arthropods unique to New York State), and did notable work on radiolarian cherts, nautiloid cephalopods, Paleozoic plankton, and a number of problematic fossils.

In structural geology, Ruedemann’s study of the exotic Rysedorph conglomerate fauna (1901) led him to suggest, in 1909, that the present position of the deformed Taconic rocks had been the result of a far-ranging westward thrust—a view now universally accepted. He thus introduced into American geology the concepts of nappe and thrust that had been so successful in Alpine geology, as demonstrated in the work of M.-A. Bertrand, Hans Schardt, M. Lugeon, and A. Heim. Ruedemann’s studies, together with those of Arthur Keith, therefore led to the ultimate resolution of the complex controversy surrounding the Taconic rocks which had long vexed American geologists. He also published stratigraphic and areal studies of the Thousand Islands (1910), Saratoga Springs (1914), the Capital District (1930), and the Catskills (1942). As a technical innovation he introduced copper electroplating of fragile gutta횪percha castings of fossils, from which molds might be obtained.

Ruedemann was vice-president (1916) of the Geological Society of America and vice-president (1911) and president (1916) of the Paleontological Society. He was elected to the National Academy of Sciences in 1928.

He was married to Elizabeth Heitzmann and they had one daughter and six sons.


I. Original Works. Among Ruedemann’s 163 scientific articles are “Development and Mode of Growth of Diplograptus M’Coy,” in New York State Geologist. Annual Report, no. 14 (1897), 217–149; “Trenton Conglomerate of Rysedorph Hill, Rensselaer Co., N. Y., and Its Fauna,” in Bulletin of the New York State Museum, no. 49 (1901), 3–114; “Guelph Fauna in the State of New York,” in Memoir of the New York State Museum, no. 5 (1903), 195, written with J. M. Clarke; “Graptolites of New York,” ibid., no. 7 (1904) and no. 11 (1908); “Cephalopods of the Beekmantown and Chazy Formations of the Champlain Basin,” Bulletin of the New York State Museum, no. 90 (1906); “Types of Inliers Observed in New York,” ibid., no. 133 (1909); “Geology of the Thousand Islands Region,” ibid., no. 145 (1910), written with H. P. Cushing, H. L. Fairchild, and C. H. Smyth, Jr.; “The Eurypterida of New York,” Memoir of the New York State Museum, no. 14 (1912), written with J. M. Clarke; “Geology of Saratoga Springs and Vicinity,” Bulletin of the New York State Museum, no. 169 (1914); “The Utica and Lorraine Formations of New York. I. Stratigraphy,” ibid., no. 258 (1925); and “II. Systematic Paleontology,” ibid., no. 262 (1925) and no. 272 (1926); “Geology of the Capital District,” ibid., no. 285 (1930); “Paleozoic Plankton of North America,” Memoir of the Geological Society of America, no. 2 (1934); and “Eastern New York Ordovician Cherts,” in Bulletin of the Geological Society of America, 47 (1936), 1535–1586, written with T. Y. Wilson.

Later publications include “Geology of the Catskill and Kaaterskill Quadrangles. Part I. Cambrian and Ordovician Geology,” Bulletin of the New York State Museum, no. 331 (1942); and especially, “Graptolites of North America,” Memoir of the Geological Society of America, no. 19 (1947).

II. Secondary Literature. On Ruedemann and his work see Winifred Goldring, “Memorial to Rudolf Ruedemann (1864–1956),” in Proceedings of the Geological Society of America. Annual Report, no. 1957 (1958), 153–162.

Donald W. Fisher

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