The Arnegard 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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Arnegard’s center stands about 2,260 ft above sea level. Within three miles the land runs from 2,170 ft to 2,390 ft, a difference of 220 ft: rolling country. The highest named summit within 15 miles is Bear Butte, about 2,550 ft, 11 miles south-southwest.
Under the town center the state geologic map shows Sentinel Butte Formation (siltstone, claystone, sandstone), from the Paleocene, 56 to 66 million years old.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 43×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Siltstone, claystone, sandstone. Age: Paleocene, 56 to 66 million years old. About 24 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 Arnegard reaches the Gulf of America by way of Timber Creek, the Missouri and the Mississippi: about 2,730 river miles.
Lakes on the way: Lake Oahe, Lake Sakakawea, Lake Sharpe and Lake Francis Case.
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 Arnegard; river miles along the main stem, rounded.
