GEOLOGY OF THE BRIDGER RANGE, MONTANA

Abstract

Research Article| November 01, 1955 GEOLOGY OF THE BRIDGER RANGE, MONTANA WILLIAM J McMANNIS WILLIAM J McMANNIS MONTANA SCHOOL OF MINES, DEPARTMENT OF GEOLOGY, BUTTE, MONTANA Search for other works by this author on: GSW Google Scholar Author and Article Information WILLIAM J McMANNIS MONTANA SCHOOL OF MINES, DEPARTMENT OF GEOLOGY, BUTTE, MONTANA Publisher: Geological Society of America Received: 08 Jun 1953 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1955, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1955) 66 (11): 1385–1430. https://doi.org/10.1130/0016-7606(1955)66[1385:GOTBRM]2.0.CO;2 Article history Received: 08 Jun 1953 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation WILLIAM J McMANNIS; GEOLOGY OF THE BRIDGER RANGE, MONTANA. GSA Bulletin 1955;; 66 (11): 1385–1430. doi: https://doi.org/10.1130/0016-7606(1955)66[1385:GOTBRM]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract In and near the Bridger Range area north and east of Bozeman, Montana, in Gallatin County, about 27,000 feet of sedimentary rocks, from Beltian to Recent, is exposed. Strata of known Ordovician, Silurian, Permian, and Triassic age are not present. Middle Cambrian Flathead sandstone is underlain by coarse Beltian arkoses in the northern part of the area and by Archean (?) metamorphics in the southern part. The depositional edge of the Belt arkoses has been fault-controlled. The Sappington formation (Berry, 1943) is separated from the underlying Three Forks formation by a minor disconformity. The Big Snowy group is recognized in the Bridger Range for the first time. The problem of the Livingston formation is reviewed, and it is apparent that the andesitic phases of these Montanan, Lancian, and Paleocene sediments can be used to interpret the tectonic history of the Crazy Mountain basin and adjacent mountain areas.Analysis of the structural features of the Bridger Range and adjacent areas indicates two phases of folding and faulting. One developed generally north-trending structures in mid-Paleocene time, and the other developed north-northwest trending structures probably in latest Paleocene or early Eocene.In Oligocene time isostatic arching produced normal faults on the west side of the Bridger Range. The range was lifted relative to the Gallatin Valley, and the east-flowing drainage was impeded so that sediments accumulated in the basins. These movements and deposition have continued sporadically to the present. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.