The Sumpter 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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Sumpter’s center stands about 4,470 ft above sea level. Within three miles the land runs from 4,240 ft to 5,840 ft, a difference of 1,600 ft: steep hill country. The highest named summit within 15 miles is Rock Creek Butte, about 9,040 ft, 7 miles northeast.
The section below crosses 9 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 5×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Argillite, chert, phyllite. Age: Permian to Triassic, 202 to 299 million years old. About 14 mi of the line.
Andesite. Age: Paleocene to Early Oligocene, 28 to 66 million years old. About 4 mi of the line.
Gabbro. Age: Permian to Triassic, 202 to 299 million years old. About 2 mi of the line.
Gravel, boulders, clay. Age: Pleistocene to Holocene, less than 2.6 million years old. About 1 mi of the line.
Basalt, basaltic-andesite, andesite. Age: Late Oligocene to Pleistocene, 1.6 to 24 million years old. About 0.8 mi of the line.
Gravel, boulders, fine-detrital. Age: Pliocene to Pleistocene, less than 5.3 million years old. About 0.8 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 3 smaller units along the line are not listed.
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 Sumpter reaches the Pacific Ocean by way of the Powder River, the Snake and the Columbia: about 760 river miles.
Lakes on the way: Lake Umatilla, Brownlee Reservoir and Hells Canyon Reservoir.
240 miles of the trip are on the Snake.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Sumpter; river miles along the main stem, rounded.
