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Pennsylvanian Rocks and Fusulinids

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During the field season of 1944, Pennsylvanian rocks exposed in parts of Wyoming, northern Colorado, and eastern Utah were studied for the Phillips Petroleum Company. Numerous fusulinid foraminifers were obtained and a study of them has given much additional information concerning stratigraphy and paleogeography of the Pennsylvanian system in that region. The field work was carried on around the north, south, and east flanks of the Uinta Mountains of eastern Utah and northwestern Colorado and in the White River uplift area of northwestern Colorado. The geographic locations of the stratigraphic sections discussed specifically in this report are shown on the accompanying index map (Fig. 1).

Figure 1—Index map of east Utah and northwest Colorado.

Index map of east Utah and northwest Colorado.

The Pennsylvanian rocks of northwestern Colorado and easternmost Utah are treated in numerous publications, including reports by Powell (1876), Hague and Emmons (1877), Girty (1903), Berkey (1905), Emmons (1907), Weeks (1907), Schultz (1918), Reeside (1923), Sears (1924), and Forrester (1937). Few of these papers discuss the Pennsylvanian in detail, however. Brill (1942) has described the Pennsylvanian rocks in the Gore area of north-central Colorado between Climax and Piney River and has extended his study (Brill, 1944) northwestward into the White River uplift and the southeastern flanks of the Uinta Mountains. Williams (1943) described Pennsylvanian and Mississippian rocks in the Uinta and Wasatch Mountains of Utah, including the type sections of the Brazer, Morgan, Weber, and Wells formations. He measured two sections on the south margin of the Uinta Mountains, one from the canyon of the North Fork of Duchesne River northwest of Duchesne, Utah, and the other from Brush Creek Canyon north of Vernal, Utah.

I had opportunity to examine the section in the Uinta Mountains discussed by Williams and Brill and some of the sections in the White River uplift discussed by Brill. I also had opportunity to examine the Pennsylvanian sections exposed in Sheep Mountain Canyon south of Manila on the north side of the Uinta Mountains, in White Rock Canyon northwest of Vernal, in Split Mountain Canyon east of Vernal, in Hell's Canyon on the southeast flank of the Uinta Mountains, at Cross Mountain east of Hell's Canyon, at Juniper Mountain Canyon of the Yampa River west of Craig, Colo., and in the region near McCoy, Colo. Fusulinid foraminifers are abundant in many of these sections. They furnish information for correlation of the Pennsylvanian rocks of northwestern Colorado and eastern Utah with those of Kansas and throw light on Pennsylvanian paleogeography west of Kansas.


I express sincere thanks to the many geologists of the Rocky Mountain area who aided in locating important localities, in supplying information about local and regional geology, or who made work possible in some regions by hospitality of living quarters. Among these are especially Henry Ley, W. T. Nightingale of the Mountain Fuel Supply Company, Harry Baldwin and J. H. Turner of the Phillips Petroleum Company, Harry Oborne, Warren Thompson, and J. Stewart Williams. Thanks are extended also to O. T. Hayward, a student at the University of Kansas, who assisted me in the field work.

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Kansas Geological Survey, Geology
Placed on web Sept. 10, 2017; originally published Oct. 15, 1945.
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