File:Geology (1907) (14773277651).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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rmation is in dispute. Some of the bedsdescribed under this name are probably younger than Oligocene. See Smith andAldrich, Science, New Series, Vol. 16, p. 836, and Vol. 18, p. 26. 7 Hill, Geology and Physical Geography of Jamaica, and Geological History ofthe Isthmus of Panama and portions of Costa Rica. Bull. Mus. Comp. Zool., Vols.XXVIII and XXXIV respectively. THE EOCENE PERIOD. 245 The Oligocene is likewise represented among the terrestrial depos-its of the western part of the continent. Following the Uinta stage(p. 209) of the Eocene, physiographic and drainage relations were sochanged as to shift the sites of notable sedimentation. The next con-siderable formation, the history of which is partially known, is theWhite River formation, lying east of the northern Rockies. It occupiesan extensive area in northeastern Colorado, southeastern Wyoming,western Nebraska (Brule and Chadron formations 1), and South Dakota,and it may extend southward even to Kansas.2 Clastic sediments pre-
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Fig. 435.—Bad Land erosion in the Brule clay, near Scotts Bluff, western Nebraska. (Darton, U. S. Geol. Surv.) dominate in the White River series, and clay predominates over coarsermaterial, but beds and lenses of sandstone and conglomerate (or sandand gravel) occur at various places, and there are thin beds and lensesof limestone and some volcanic ash. The origin of the White River beds has been the occasion of muchdifference of opinion. They have usually been described as lacustrine,but in recent years parts of them have been regarded as partly or 1 Darton, Camp Clarke, Scotts Bluff, Edgemont, and Oelrichs folios, U. S. Geol. Surv 2 Adams, Am. Geol, Vol. 29, p. 303. 24G 0E0L001 wholly fluviatile,1 and even as eolian.2 The eolian origin has beenurged on tin* basis of (Ik* fossils, which are chiefly those of land animals(land tortoises ami mammals); but while much may be said for thishypothesis as applied to parts of the formation, it docs not seem appli-cable to all of it, as the c

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