Research Article| May 01, 1939 Glacial geology of Grand Coulee Dam, Washington RICHARD FOSTER FLINT; RICHARD FOSTER FLINT Search for other works by this author on: GSW Google Scholar WILLIAM H. IRWIN WILLIAM H. IRWIN Search for other works by this author on: GSW Google Scholar Author and Article Information RICHARD FOSTER FLINT WILLIAM H. IRWIN Publisher: Geological Society of America Received: 23 Dec 1938 First Online: 02 Mar 2017 Online Issn: 1943-2674 Print Issn: 0016-7606 © 1939 Geological Society of America GSA Bulletin (1939) 50 (5): 661–680. https://doi.org/10.1130/GSAB-50-661 Article history Received: 23 Dec 1938 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 RICHARD FOSTER FLINT, WILLIAM H. IRWIN; Glacial geology of Grand Coulee Dam, Washington. GSA Bulletin 1939;; 50 (5): 661–680. doi: https://doi.org/10.1130/GSAB-50-661 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 Sections of the fill in Columbia canyon near Grand Coulee Dam, together with the stratigraphy and morphology of related features downstream, record the expansion and later shrinkage of the Okanogan glacier lobe during the last glaciation. Three stratigraphic zones are recognized: (1) A Basal Sequence of lacustrine fines inter-bedded with fluvial sediments, recording oscillatory ponding of the Columbia River as the glacier dammed it downstream. At first the lake was shallow and drained west around the ice margin. Later it was more effectively dammed, deepened, and forced to discharge south through Grand Coulee. (2) A Till Zone, recording the arrival of ice, with fluctuations, at Grand Coulee Dam during the glacial climax. (3) Later deposits stratigraphically (but not everywhere vertically) overlying the Till Zone, recording oscillatory deglaciation accompanied by transition from lacustrine to fluvial conditions.The San Poil glacier lobe entered the lake-filled Columbia canyon at Keller Ferry, 15 miles upstream from Grand Coulee Dam, and contributed sediment to the lake. The maximum of this lobe appears to have been approximately contemporaneous with the maximum of the neighboring Okanogan lobe.While residual ice was still present locally in Columbia canyon downstream, drain-age abandoned Grand Coulee and resumed its former (and present) course. Thereafter, grading of the long profile of Columbia River proceeded both by erosion of the lake fill and by deposition in depressions partly of ice-block origin and was marked by at least one delay recorded by a particularly conspicuous stream terrace. 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.
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