The Porcupine 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
Mostly sunny; warmer
Mostly sunny
Partly cloudy
Partly cloudy
Partly cloudy
Showers likely
78° on Nov. 17, 2017, the hottest reading for this week of the year since 1956. Next is 77° in 2016.
Porcupine’s center stands about 3,340 ft above sea level. Within three miles the land runs from 3,050 ft to 3,510 ft, a difference of 460 ft: hilly country. The highest named summit within 15 miles is Porcupine Butte, about 3,640 ft, 6 miles south.
Under the town center the state geologic map shows Arikaree Group (siltstone, sandstone), from the Oligocene to Miocene, 5.3 to 34 million years old.
The section below crosses 4 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 25×. 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, sandstone. Age: Oligocene to Miocene, 5.3 to 34 million years old. About 19 mi of the line.
Silt, sand. Age: Quaternary, less than 2.6 million years old. About 3 mi of the line.
Coarse-detrital, clay. Age: Quaternary, less than 2.6 million years old. About 1 mi of the line.
Coarse-detrital, fine-detrital. Age: Quaternary, less than 2.6 million years old. About 0.8 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 Porcupine reaches the Gulf of America by way of Porcupine Creek, the White River, the Missouri and the Mississippi: about 2,490 river miles.
Lakes on the way: 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 Porcupine; river miles along the main stem, rounded.
Porcupine has a hot-summer humid continental climate. Summer afternoons average 88° in July; winter nights fall to about 11° in January. About 22 inches of rain fall in a normal year.
Normals 1991–2020 and records since 1956 at Kyle 2 E, 15 miles northeast, 380 ft lower. NOAA, through RCC-ACIS.
