Download torrent Bulletin - United States Geological Survey Volume 350

Bulletin - United States Geological Survey Volume 350 by Geological Survey

---------------------------------------------------------------
Author: Geological Survey
Page Count: 26 pages
Published Date: 22 May 2012
Publisher: Rarebooksclub.com
Publication Country: Miami Fl, United States
Language: English
ISBN: 9781236436658
Download Link: Bulletin - United States Geological Survey Volume 350
---------------------------------------------------------------

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1908 Excerpt: ...incursions of the sea and reestablishment of salt-water conditions. The Judith River beds of Montana and the Mesaverde formation of Colorado are examples of deposits laid down during such periods. Both contain a fauna and flora resembling those of the Laramie and were formerly supposed to be Laramie. Both are now known, however, to represent stages of fresh-water deposition somewhat similar to those which prevailed during Laramie time, but occurring long before the close of the Cretaceous. It is perfectly clear that such beds can not be included under any interpretation which can be reasonably given to the original definition and agreement as to the vise of the term Laramie. The fact that Mesaverde time was succeeded by a considerable period of true marine deposition was entirely unrecognized at the time of the earlier surveys. Evidence of this return of salt-water conditions is found in the existence of a normal succession of marine strata overlying the Mesaverde formation in the Yampa River valley, north of the fields structurally included with those of the White River districts. The Yampa basin contains a great body of dark clay shale with lenticular interbedded sandstones and calcareous layers, overlain by a second large body of sandstones, sandy shales, and coal beds. Of these deposits the lower or shale group (Lewis shale) is of marine origin and the overlying beds indicate a second transitory stage, reintroducing brackish and fresh-wafer conditions. The later beds are thought to represent, at least in part, the Laramie, so far as the best interpretation of that term is at present understood. STRUCTURE. GENERAL FEATURES. The geologic structure of the region here discussedban best be described by means of graphic sections. Several of these have been co...

Read online Bulletin - United States Geological Survey Volume 350 Buy and read online Bulletin - United States Geological Survey Volume 350 Download Bulletin - United States Geological Survey Volume 350 for pc, mac, kindle, readers Download to iPad/iPhone/iOS, B&N nook Bulletin - United States Geological Survey Volume 350 ebook, pdf, djvu, epub, mobi, fb2, zip, rar, torrent