The Coulee City plate. Relief from Copernicus GLO-30; rivers and lakes from USGS NHD; watersheds from the USGS Watershed Boundary Dataset; roads and city limits from Census TIGER 2024.
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Coulee City’s center stands about 1,600 ft above sea level. Within three miles the land runs from 1,240 ft to 1,930 ft, a difference of 690 ft: hilly country. The highest named summit within 15 miles is Gilbert Butte, about 2,500 ft, 5 miles west-northwest.
Under the town center the state geologic map shows Miocene volcanic rocks (basalt), from the Late Oligocene to Early Pliocene, 3.6 to 28 million years old.
The section below crosses 3 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 14×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Basalt. Age: Late Oligocene to Early Pliocene, 3.6 to 28 million years old. About 9 mi of the line.
Sand, gravel. Age: Pleistocene, less than 2.6 million years old. About 8 mi of the line.
Silt. Age: Pleistocene, less than 2.6 million years old. About 6 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale.
Heights from Copernicus GLO-90 (a surface model: it includes buildings and tree canopy); summits from USGS GNIS; rivers from USGS NHDPlus HR; rock from the USGS State Geologic Map Compilation.
A raindrop that lands in Coulee City reaches the Pacific Ocean by way of Crab Creek, Lower Crab Creek and the Columbia: about 510 river miles.
Lakes on the way: Lake Umatilla, Potholes Reservoir and Moses Lake.
210 miles of the trip are on the Columbia.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Coulee City; river miles along the main stem, rounded.
