Events Calendar

Ice Age Floods presentation
Tuesday 10 September 2019, 06:45pm - 08:30pm
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Lake Lewis Chapter of the Ice Age Floods

Moses Coulee is the oddball canyon of the Channeled Scabland. While it is known that Pleistocene megafloods eroded the Channeled Scabland canyons, including Moses Coulee, Moses Coulee is unique from other Scabland canyons because it lacks connectivity to the Columbia River. Moses Coulee heads in the middle of the Waterville Plateau, lacking obvious feeder channels or flood-scoured surfaces that link to the Columbia River. J Harlen Bretz, in his late 1950’s publications, suggested that the connection between the Columbia River and Moses Coulee was eroded by Okanogan Lobe glaciation, and/or buried by glacial sediments. Larry Hanson, in his 1970’s thesis, identified the Mansfield Channels, a diffuse zone of low-relief channelization on the Waterville Plateau, and argued that these features conveyed water from the Columbia River to the head of Moses Coulee. In 2009, Jerome Lesemann and Tracy Brennand published evidence for subglacial flooding in the Canadian Okanogan, and suggested that subglacial floods drained directly into Moses Coulee. I am investigating these distinct possibilities for flooding of Moses Coulee through field mapping supported with geochronologic, geochemical, and petrographic analysis. I will review what is already known about Moses Coulee from the pioneering studies of Bretz, Hanson, and others, and then present new results including field mapping, geochemical analysis of flood silts, petrographic analysis of flood sands, and calculations of subglacial water flow beneath the Okanogan Lobe. 

Location Benton PUD Auditorium 2721 10th Ave. Kennewick