The Sisters 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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Sisters’s center stands about 3,200 ft above sea level. Within three miles the land runs from 3,040 ft to 3,510 ft, a difference of 470 ft: hilly country. The highest named summit within 15 miles is North Sister, about 9,900 ft, 14 miles southwest.
Under the town center the state geologic map shows Lacustrine and fluvial sedimentary rocks (clay, silt, sand), from the Pleistocene, less than 2.6 million years old.
The section below crosses 7 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.
Basaltic-andesite, basalt. Age: Quaternary, less than 2.6 million years old. About 8 mi of the line.
Basalt. Age: Miocene to Pliocene, 2.6 to 23 million years old. About 6 mi of the line.
Sandstone, siltstone, mudstone. Age: Miocene to Pliocene, 2.6 to 23 million years old. About 3 mi of the line.
Clay, silt, sand. Age: Pleistocene, less than 2.6 million years old. About 3 mi of the line.
Gravel, sand, boulders. Age: Pleistocene, less than 2.6 million years old. About 2 mi of the line.
Basaltic-andesite, basalt. Age: Early Pliocene to Pleistocene, 1.2 to 3.9 million years old. About 1 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 1 smaller unit 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 Sisters reaches the Pacific Ocean by way of Indian Ford Creek, Squaw Creek, the Deschutes and the Columbia: about 350 river miles.
Lake on the way: Lake Billy Chinook.
200 miles of the trip are on the Columbia.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Sisters; river miles along the main stem, rounded.
