The North Spearfish 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.
Partly cloudy
Sunny
Mostly sunny
Partly cloudy
Partly cloudy; cooler
Partly cloudy
Showers likely
−23° on Nov. 16, 1959, the coldest reading for this week of the year since 1893. Next is −15° in 1916.
North Spearfish’s center stands about 3,640 ft above sea level. Within three miles the land runs from 3,390 ft to 4,490 ft, a difference of 1,100 ft: steep hill country. The highest named summit within 15 miles is Terry Peak, about 7,040 ft, 13 miles south-southeast.
The section below crosses 12 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 6×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Coarse-detrital, fine-detrital. Age: Quaternary, less than 2.6 million years old. About 4 mi of the line.
Coarse-detrital, clay. Age: Quaternary, less than 2.6 million years old. About 3 mi of the line.
Hypabyssal-trachyte, hypabyssal-quartz-trachyte, hypabyssal-rhyolite. Age: Paleocene to Eocene, 34 to 66 million years old. About 3 mi of the line.
Sandstone, siltstone, shale. Age: Late Pennsylvanian to Permian, 273 to 307 million years old. About 3 mi of the line.
Siltstone, sandstone, shale. Age: Permian, 252 to 299 million years old. About 3 mi of the line.
Claystone, conglomerate, sandstone. Age: Early Cretaceous, 100 to 145 million years old. About 3 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 6 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 North Spearfish reaches the Gulf of America by way of Spearfish Creek, Redwater Creek, the Belle Fourche, the Cheyenne, the Missouri and the Mississippi: about 2,570 river miles.
Lakes on the way: Lake Oahe, Lake Sharpe, Lake Francis Case and Lewis and Clark Lake.
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 North Spearfish; river miles along the main stem, rounded.
North Spearfish has a warm-summer humid continental climate. Summer afternoons average 84° in July; winter nights fall to about 16° in January. A normal year brings about 70 inches of snow; with the rain, that comes to about 21 inches of water.
On November 14 North Spearfish normally reaches 46° and falls to 26°. The record high is 76°, in 1894; the record low −20°, in 1959. The most rain on this date, 2.67 in, fell in 1944.
Normals 1991–2020 and records since 1893 at Spearfish, here. NOAA, through RCC-ACIS.
