The Loon Lake 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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Loon Lake’s center stands about 2,420 ft above sea level. Within three miles the land runs from 2,280 ft to 3,400 ft, a difference of 1,120 ft: steep hill country. The highest named summit within 15 miles is Boyer Mountain, about 5,270 ft, 13 miles northeast.
Under the town center the state geologic map shows Glacial drift, undivided (sand, gravel), from the Pleistocene, less than 2.6 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 8×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Granite. Age: Precambrian to Eocene. About 11 mi of the line.
Argillite, siltstone. Age: Mesoproterozoic to Early Cambrian, 521 to 1,600 million years old. About 7 mi of the line.
Sand, gravel. 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 Loon Lake reaches the Pacific Ocean by way of Sheep Creek, the Colville and the Columbia: about 760 river miles.
Lake on the way: Lake Umatilla.
410 miles of the trip are on the Columbia.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Loon Lake; river miles along the main stem, rounded.
