The Elkhorn 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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Elkhorn’s center stands about 6,480 ft above sea level. Within three miles the land runs from 5,780 ft to 9,150 ft, a difference of 3,370 ft: mountain country. The highest named summit within 15 miles is Crow Peak, about 9,390 ft, 2 miles east-northeast.
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 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.
Andesite, latite. Age: Late Cretaceous, 72 to 84 million years old. About 14 mi of the line.
Granitic. Age: Cretaceous, 66 to 145 million years old. About 7 mi of the line.
Age: Late Miocene to Holocene, less than 7.2 million years old. About 1 mi of the line.
Limestone. Age: Middle Mississippian, 331 to 347 million years old. About 1 mi of the line.
Limestone, dolostone, shale. Age: Late Devonian to Early Mississippian, 347 to 374 million years old. About 0.6 mi of the line.
Shale, limestone, sandstone. Age: Middle Cambrian to Cambrian, 487 to 521 million years old. About 0.6 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 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 Elkhorn reaches the Gulf of America by way of Elkhorn Creek, the Boulder, Jefferson Slough, the Jefferson, the Missouri and the Mississippi: about 3,560 river miles.
Lakes on the way: Lake Oahe, Lake Sakakawea, Lake Fort Peck and Lake Sharpe.
1,170 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Elkhorn; river miles along the main stem, rounded.
