I have been missing a few map Monday for no good reason, so maybe I can get in the grove again.
This week map is of "Great Falls of the Columbia" (aka Celilo Falls). The falls was on the Columbia River, just east of the Dallas on the border of Washington and Oregon. I use "was" because it was drowned by the construction of the Dalles Dam in 1957. The falls themselves are local knickpoints at a layer of basalt (part of the Columbia River Basalt Group).
Map Information Allen, P., Biddle, N., Clark, W., Lewis, M. 1814. Great Falls of the Columbia. from History Of The Expedition Under The Command Of Captains Lewis And Clark, To The Sources Of The Missouri, Thence Across The Rocky Mountains And Down The River Columbia To The Pacific Ocean. Performed During The Years 1804-5-6.