The Simms 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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73° on Nov. 12, 1999, the hottest reading for this week of the year since 1912. Next is 72° in 1990.
Simms’s center stands about 3,570 ft above sea level. Within three miles the land runs from 3,510 ft to 4,300 ft, a difference of 790 ft: hilly country. The highest named summit within 15 miles is Skull Butte, about 5,650 ft, 14 miles south-southeast.
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 9 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 16×. 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, limestone, dolostone. Age: Late Cretaceous, 84 to 90 million years old. About 7 mi of the line.
Age: Late Miocene to Holocene, less than 7.2 million years old. About 5 mi of the line.
Sandstone, siltstone, mudstone. Age: Late Cretaceous, 66 to 84 million years old. About 4 mi of the line.
Sandstone. Age: Late Cretaceous, 72 to 84 million years old. About 2 mi of the line.
Age: Pleistocene to Holocene, less than 1.8 million years old. About 2 mi of the line.
Syenitic. Age: Cretaceous, 66 to 145 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. 3 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 Simms reaches the Gulf of America by way of the Sun River, the Missouri and the Mississippi: about 3,320 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 Simms; river miles along the main stem, rounded.
Simms has a cold semi-arid climate. Summer afternoons average 83° in July; winter nights fall to about 13° in January. About 13 inches of rain fall in a normal year.
On November 14 Simms normally reaches 45° and falls to 22°. The record high is 72°, in 1999; the record low −17°, in 2014. The most rain on this date, 0.17 in, fell in 1988.
Normals 1991–2020 and records since 1912 at Sun River 4 S, 9 miles east. NOAA, through RCC-ACIS.
