File:Geology (1907) (14796302093).jpg

Identifier: geology00cham (find matches)
Title: Geology
Year: 1907 (1900s)
Authors: Chamberlin, Thomas C. (Thomas Chrowder), 1843-1928 Salisbury, Rollin D., 1859- joint author
Subjects: Geology
Publisher: New York, H. Holt and co.
Contributing Library: Internet Archive
Digitizing Sponsor: Internet Archive

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era: a. Xodosaria baciUum Defrance; b, X. communis(dOrbigny); c, Anomalina ammonoides (Reuss); d, Cristellaria gibba dOrbigny;e, C. radiata (Bornemann); /, g, and h, Globigerina bulloides dOrbigny; i, Vagina-Una legumen (Linne); j, Discorbina turbo (dOrbigny): k, Truncatulina lobatula(Walker and Jacob); I, Textularia subangulata dOrbigny. Magnified 10 to 50times. (Maryland Geological Survey.) of the later history, but they do not record any further profound bio-logical transformations. They stand in striking contrast with the radicaland rapid evolution of the placental mammalians. Geologically, the most striking feature of the marine Eocene lifewas the extraordinary abundance and size of the foraminifers. Mas-sive beds of limestone in the Paris basin were largely made up of thetests of Mitiola. Other Eocene limestones were formed chiefly of Or-bitolites, Orbitoides, Operculina, and Alveolina, while the nummulitic lime-stone, whose wide range and great importance has already been indi-
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Fig. 434.—Eocene Molluscs: Gastropods: a, Fusus (?) interstriatus Heilprin;b, Mitra potomacensis Clark and Martin; c, Pleurotoma tysoni Clark and Martin;d, P. potomacensis Clark and Martin; e, Scala potomacensis Clark and Martin;Tornatelhva bella Conrad; y, Turritella mortoni Conrad; h, Lunatia marylandicaConrad. Pelecypods: i, Glycymeris idoneus (Conrad); /, Dosiniopis ienticu-laris (Rogers); k and /, Corbula aldrichi Meyer; m and n, Protocardia levis Conrad;o and p, Yenericardia marylandica Clark and Martin; q, Modiolus alabamensisAldrich; r, Leda parilis (Conrad); s, Lucina aquiana Clark; t, Crassatellites alo3-Jormis (Conrad); u, Ostrea eompressirostra Say; v, Nucula ovula Lea; v), Pectenchoctaicensis Aldrich, (After Maryland Geological Survey.) THE EOCENE PERIOD. 243 cated, was made up largely of the coin-like Nummidites, which lived inprodigious abundance. The gastropods and pelecypods of modern typesbecame very prolific, while the cephalopods were markedly less impor-tant tha

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