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STRATIGRAPHIC SEQUENCE IN THE EAGLE ROCK VOLCANIC AREA NEAR AMERICAN FALLS, IDAHO

1956; Geological Society of America; Volume: 67; Issue: 1 Linguagem: Inglês

10.1130/0016-7606(1956)67[19

1943-2674

Harold T. Stearns, ANDREI ISOTOFF,

Botany, Ecology, and Taxonomy Studies

Research Article| January 01, 1956 STRATIGRAPHIC SEQUENCE IN THE EAGLE ROCK VOLCANIC AREA NEAR AMERICAN FALLS, IDAHO HAROLD T STEARNS; HAROLD T STEARNS HOPE, IDAHO: IDAHO STATE COLLEGE, POCATELLO, IDAHO Search for other works by this author on: GSW Google Scholar ANDREI ISOTOFF ANDREI ISOTOFF HOPE, IDAHO: IDAHO STATE COLLEGE, POCATELLO, IDAHO Search for other works by this author on: GSW Google Scholar GSA Bulletin (1956) 67 (1): 19–34. https://doi.org/10.1130/0016-7606(1956)67[19:SSITER]2.0.CO;2 Article history received: 03 Jan 1955 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 HAROLD T STEARNS, ANDREI ISOTOFF; STRATIGRAPHIC SEQUENCE IN THE EAGLE ROCK VOLCANIC AREA NEAR AMERICAN FALLS, IDAHO. GSA Bulletin 1956;; 67 (1): 19–34. doi: https://doi.org/10.1130/0016-7606(1956)67[19:SSITER]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 Excellent exposures in Snake River canyon in the Eagle Rock area near American Falls, Idaho, were supplemented by numerous drill holes in connection with the exploration for a damsite. The rocks are Lower Pliocene (?) Neeley lake beds and associated basaltic and siliceous sediments and tuffs possibly correlative with the Salt Lake formation to the east and the Payette formation to the west. Above the Neeley formation a welded rhyolite tuff (ignimbrite) contains lithophysae and spherulites and shows four distinct phases. Next higher is a siliceous tuffaceous shallow-water sediment, a thin-bedded sublacustrine basaltic tuff, with very thin diatomaceous interbeds, and finally thick basaltic tuffs, breccias, dikes, and lava flows of the Massacre volcanics. Agglutinated basaltic tuffs are also present. Unconformable on these rocks are the Raft lake beds, possibly correlative with the Lake Idaho deposits farther west, of late Pliocene age. A major erosional unconformity separates the Tertiary rocks from the late Pleistocene Cedar Butte basalt which displaced Snake River for 55 miles and produced a lake 40 miles long and 12 miles wide. The beds deposited by this lake constitute the American Falls formation. Abandoned spring coves cut in the downstream end of the Cedar Butte basalt testify to heavy leakage from this ancient lake. The region was warped into gentle anticlines and synclines near the close of the Tertiary and faulted into small blocks. Several erosional unconformities were found. The petrography is described. 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.