The Lake Missoula Floods and the Channeled Scabland Author(s): J. Harlen Bretz Source: The Journal of Geology, Vol. 77, No. 5 (Sep., 1969), pp. 505-543 Published by: The University of Chicago Press Stable URL: http://www.jstor.org/stable/30062250 . Accessed: 15/01/2015 10:22 Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp . JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact
[email protected]. The University of Chicago Press is collaborating with JSTOR to digitize, preserve and extend access to The Journal of Geology. http://www.jstor.org This content downloaded from 128.193.164.203 on Thu, 15 Jan 2015 10:22:29 AM All use subject to JSTOR Terms and Conditions THE LAKE MISSOULA FLOODS AND THE CHANNELED SCABLAND1 J HARLEN BRETZ Department of the Geophysical Sciences, University of Chicago ABSTRACT This paper reviews the outstanding evidence for (1) repeated catastrophic outbursts of Montana's glacially dammed Lake Missoula, (2) consequent overwhelming in many places of the preglacial divide along the northern margin of the Columbia Plateau in Washington, (3) remaking of the plateau's preglacial drainage pattern into an anastomosing complex of floodwater channels (Channeled Scabland) locally eroded hundreds of feet into underlying basalt, (4) convergence of these flood-born rivers into the Columbia Valley at least as far as Portland, Oregon, and (5) deposition of a huge delta at Portland.