Sharing the Fascinating Ice Age Floods Story Since 1995
When the Ice Age Floods reached Wallula Gap there was far too much water to pass through that sole gap in the Horse Heaven Hills. The gap became a hydraulic dam that caused the flood waters to back up even as the floods poured through the gap. The backed up waters formed a huge temporary Lake Lewis that filled the upstream area before all the flood waters eventually passed through Wallula Gap in up to a couple of weeks time.
With each of the many Ice Age Floods, some of the sediment scoured off the upstream Channeled Scablands settled out of the relatively quiet lake waters and was deposited as rhythmites, thin stacked beds of sediment that now are recognized as a record of 40 of the floods that passed through the area.
The White Cliffs in the Hanford Reach National Monument tend to be much thicker beds of sand and silt laid down earlier by the Columbia River between 9 and 3 million years ago when the path of the river became blocked and forced eastward to Wallula Gap by the rise of Rattlesnake Mountain and the Horse Heaven Hills due to north-to-south compression of the Columbia Plateau.
Underlying both are the tabular layers of Columbia River Basalt that were mainly laid down 17 to 14 million years ago as flat lying layers that are over 2 miles thick near the Tri-Cities area.
The Lake Lewis Chapter is based in the Tri-Cities, WA, and represents south-central and southeastern Washington and adjacent areas in Idaho and Oregon.
The chapter is named for Lake Lewis, the large temporary lake that formed in the Pasco Basin when floodwaters were held back by the hydraulic dam caused by Wallula Gap.
Chapter Meetings
The Lake Lewis Chapter meets six times a year (Jan., Mar., May, July, Sept., Nov.) on the second Tuesday of the month, at the Battelle Auditorium (click here to display map), 900 Battelle Blvd., in Richland, or other alternate locations.
Meetings begin at 6:45 p.m. with a lecture presentation, followed by a business meeting.
Meetings are always free and open to the public.
To confirm meeting information, contact the chapter president.
Community Activities and Partners
The Lake Lewis Chapter is actively engaged in the community. Our speakers bureau gives lectures to educational institutions, Rotary and other community organizations, professional society meetings, and others. We have participated in a number of local and regional community events including the Coulee Corridor Big Event, the Sandhill Crane Festival, and the Tri-Cities Visitor and Convention Bureau’s annual meetings, county fairs, gem and mineral shows, etc.
We have strong partnerships with several important community organizations, including the CREHST museum, the Hanford Reach National Monument, the Tri-Cities Visitor and Convention Bureau, Friends of Badger Mountain, City of Richland, Battelle, the East Benton County Historical Society, the Franklin County Historical Society, the Hanford Reach National Monument, the Fish and Wildlife Service, Bergstrom Aircraft, and the Mid-Columbia Library. The Mid-Columbia Library has been provided a list of recommended titles and some materials about the Ice Age Floods. The library has many related titles on the shelves and will continue to acquire more Floods material.
Please see the Upcoming Events or the General Events Calendar for a listing of all chapter meetings and events.
Bruce Bjornstad – (509) 373-6948
George Last – (509) 946-8050
Chris Murray – (509) 946-7217
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