The Grass Range 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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Showers likely; cooler
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−26° on Nov. 13, 1955, the coldest reading for this week of the year since 1914. Next is −25° in 1959.
Grass Range’s center stands about 3,490 ft above sea level. Within three miles the land runs from 3,380 ft to 3,980 ft, a difference of 600 ft: hilly country. The highest named summit within 15 miles is Button Butte, about 4,480 ft, 6 miles 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 11 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 9×. 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, 94 to 100 million years old. About 6 mi of the line.
Gravel, sand, silt. Age: Pleistocene to Holocene, less than 1.8 million years old. About 4 mi of the line.
Limestone, dolostone. Age: Early Pennsylvanian, 315 to 324 million years old. About 2 mi of the line.
Mudstone, siltstone, limestone. Age: Late Mississippian, 324 to 331 million years old. About 2 mi of the line.
Sandstone. Age: Early Cretaceous, 100 to 113 million years old. About 2 mi of the line.
Mudstone, siltstone, sandstone. Age: Early Cretaceous, 100 to 133 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. 5 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 Grass Range reaches the Gulf of America by way of South Fork McDonald Creek, McDonald Creek, Box Elder Creek, Flatwillow Creek, the Musselshell, the Missouri and the Mississippi: about 3,210 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 Grass Range; river miles along the main stem, rounded.
Grass Range has a warm-summer humid continental climate. Summer afternoons average 83° in July; winter nights fall to about 14° in January. A normal year brings about 50 inches of snow; with the rain, that comes to about 18 inches of water.
On November 14 Grass Range normally reaches 47° and falls to 23°. The record high is 75°, in 1999; the record low −15°, in 1959. The most rain on this date, 0.19 in, fell in 2005.
Normals 1991–2020 and records since 1914 at Grass Range, here. NOAA, through RCC-ACIS.
