The Shawmut 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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72° on Nov. 13, 2025, the hottest reading for this week of the year since 1909. Next is 71° in 1953.
Shawmut’s center stands about 3,850 ft above sea level. Within three miles the land runs from 3,800 ft to 4,250 ft, a difference of 450 ft: hilly country. The highest named summit within 15 miles is Wild Horse Butte, about 4,800 ft, 10 miles west.
Under the town center the state geologic map shows Alluvium (gravel, sand, silt), from the Pleistocene to Holocene, less than 1.8 million years old.
The section below crosses 10 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 20×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Shale. Age: Late Cretaceous, 72 to 84 million years old. About 6 mi of the line.
Black-shale, sandstone. Age: Late Cretaceous, 94 to 100 million years old. About 4 mi of the line.
Shale. Age: Early Cretaceous, 100 to 113 million years old. About 3 mi of the line.
Shale, limestone, dolostone. Age: Late Cretaceous, 84 to 90 million years old. About 3 mi of the line.
Gravel, sand, silt. Age: Pleistocene to Holocene, less than 1.8 million years old. About 2 mi of the line.
Sandstone, siltstone, shale. Age: Late Cretaceous, 84 to 87 million years old. About 2 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 4 smaller units 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 Shawmut reaches the Gulf of America by way of the Musselshell, the Missouri and the Mississippi: about 3,300 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 Shawmut; river miles along the main stem, rounded.
Shawmut has a cold desert climate. Summer afternoons average 86° in July; winter nights fall to about 14° in December. Barely 0.0 inches of rain fall in a normal year.
On November 14 Shawmut normally reaches 46° and falls to 23°. The record high is 71°, in 1953; the record low −11°, in 2014. The most rain on this date, 0.34 in, fell in 1996.
Normals 1991–2020 and records since 1909 at Ryegate, 13 miles east-southeast, 200 ft lower. NOAA, through RCC-ACIS.
