Wallula Gap, Washington
Posted by: 
Rose Red
N 46° 02.007 W 118° 56.107
11T E 350250 N 5099584
Wallula Gap is a large water gap through basalt anticlines in the Columbia River basin just south of the confluence of the Walla Walla and Columbia rivers.
Waymark Code: WM1X3R
Location: Washington, United States
Date Posted: 07/24/2007
Views: 75
Glacial-outburst waters that crossed the Channeled Scablands during the Missoula Flood of 15,000–12,000 years ago were channeled through Wallula Gap. Wallula Gap is a large water gap through basalt anticlines in the Columbia River basin just south of the confluence of the Walla Walla and Columbia rivers.
For several weeks, as much as 200 cubic miles of flood waters per day roared to a gap that could discharge less than 40 cubic miles per day. The peak flow is estimated to have been about 10 million cubic meters per second (about 50 times the flow of the Amazon River, and ten times the combined flow of all the rivers in the world).
Because the constriction at Wallula Gap was only 1 mile wide, the flood waters back-flooded into the Pasco Basin and up the Yakima Valley to the Yakima and up the Snake River to the mouth of the Salmon River (including the Touchet valley) to form, for a short period of time, Lake Lewis.
The area was scoured by floodwaters traveling about 40 to 45 mph that overflowed the top of the gap. This left the most solid of the ancient lava flows as buttes (steep, flat-topped hill) and mesas (small, isolated flat-topped structures with steep, rocky sides) such as "The Sisters" and “Hat Rock”.
Instructions for logging waymark: A photograph is required of you (or your GPS receiver, if you are waymarking solo) and Wallula Gap.
Elevation (Official or GPSR reading): 403
Mountain Range: Basalt anticlines in the Columbia River basin
Access:
I took the coordinates and photographs from a tour bus heading west on Hwy 730. Another great view is located at Spring Gulch Creek just south of Wallula Gap.
|
Visit Instructions:
Pictures are encouraged but not required.