After passing through Sentinel Gap on our Saturday drive, I arbitrarily picked a side road and headed west toward the Columbia to see if I could get a different perspective of the Gap. The road ended up at a small boat ramp on a backwater pond near the river. The sun was just about ready to drop behind Umptanum Ridge. The late afternoon created a beautiful glow on the grasses and winter tree trunks. As a little bonus, I was able to get a piece fo the western ridge of Sentinal Gap in my image. For reference, the height of the water in the Columbia River approached the top of this ridge during the Missoula Floods. The area where I was standing when taking this image was at the bottom of Ice Age Lake Lewis. The water would have been several hundred feet above my head during the floods.
Sentinel Gap Looking South from Frenchman’s Spring Coulee
This image was taken from the bottom of Frenchman’s Spring Coulee near where it enters the Columbia River. Sentinel Gap was cut across the Saddle Mountains by the Columbia River and the Ice Age Floods. During the floods, the Columbia River was at a level near the top of the eastern slope of the Gap. On the north side of the Gap, the Vantage Bridge and Wanapum Dam are faintly visible. Through the Gap, Umatilla and Rattlesnake Ridges are visible. And of course, the clouds make the image.
This image was taken looking north through Sentinel Gap. This gap cuts through the Saddle Mountains which separate the Pasco and Othello basins in Eastern Washington. The Columbia River runs through this gap on its way to the Oregon/Washington border. At the time of the Missoula Floods, the water level going through the gap reached the top of the left ridge, flowing into Lake Lewis which covered the Pasco basin.
The erratics in the foreground most likely are from the gap, carved away by the raging wall of water that flowed through it.