The Twin Lakes 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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Twin Lakes’s center stands about 2,590 ft above sea level. Within three miles the land runs from 2,220 ft to 3,670 ft, a difference of 1,450 ft: steep hill country. The highest named summit within 15 miles is Paint Rock, about 6,350 ft, 13 miles north-northwest.
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 4×. 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 12 mi of the line.
Sand, gravel. Age: Pleistocene, less than 2.6 million years old. About 5 mi of the line.
Graywacke, quartzite. Age: Ordovician, 445 to 487 million years old. About 5 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 Twin Lakes reaches the Pacific Ocean by way of Stranger Creek and the Columbia: about 680 river miles.
Lake on the way: Lake Umatilla.
390 miles of the trip are on the Columbia.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Twin Lakes; river miles along the main stem, rounded.
