The Sprague 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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Sprague’s center stands about 2,000 ft above sea level. Within three miles the land runs from 1,880 ft to 2,250 ft, a difference of 370 ft: rolling country. The highest named summit within 15 miles is Watermelon Hill, about 2,240 ft, 5 miles east-northeast.
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 2 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 32×. 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 18 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 Sprague reaches the Pacific Ocean by way of Negro Creek, Cow Creek, the Palouse, the Snake and the Columbia: about 450 river miles.
Lake on the way: Lake Umatilla.
210 miles of the trip are on the Columbia.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Sprague; river miles along the main stem, rounded.
