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Published March 1, 1941 | public
Journal Article

Stratigraphy of the Belt series in Libby and Trout Creek quadrangles, northwestern Montana and northern Idaho

Abstract

Three formations of the Belt series—Prichard, Wallace, and Striped Peak—can be traced northward from the northeastern part of the Coeur d'Alene district, Idaho, through the Trout Creek quadrangle to the northern part of the Libby quadrangle, Montana. The differences upon which the separation of the Burke, Revett, and St. Regis is based in the Coeur d'Alene district, however, become less definite northward and fail entirely beyond the Clark Fork. In the area under consideration, therefore, these three are grouped under the term Ravalli according to the usage adopted by Calkins. Stratigraphic details of parts of the Ravalli group and the Wallace and Striped Peak formations are given in tabular sections. Certain beds of the Wallace in the Trout Creek quadrangle show "molar tooth" structures similar to those of the Siyeh and Kitchener formations along the international boundary. In the Libby quadrangle both the Wallace and the Striped Peak contain beds of dolomitic limestone showing fossil algal forms similar to those in Glacier National Park.

Additional Information

© 1941 Geological Society of America. Manuscript received by the Secretary of the Society, June 27, 1940. Published with the permission of the director, U.S. Geological Survey. The Libby quadrangle was mapped for the United States Geological Survey. The mapping of part of the Trout Creek quadrangle was an independent project undertaken by Jenks to help correlate the Belt rocks of northwestern Montana with those in the Coeur d'Alene district of Idaho. The writers were assisted in the field by P. C. Henshaw, O. W. Jarrell, C. B. Moke, J. H. Moses, R. P. Sharp, R. H. Svendsen, and A. W. Waldo. Messrs. G. F. Loughlin and J. T. Pardee of the Survey furnished helpful guidance in the field and in the preparation of the manuscript. Professors P. E. Raymond and M. P. Billings of Harvard University critically read the manuscript. Mr. E. A. Schmitz aided in draughting the maps. Grants from the California Institute of Technology and from the Milton Fund at Harvard University helped finance the project.

Additional details

Created:
August 19, 2023
Modified:
October 23, 2023