The The Silos 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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74° on Nov. 12, 1999, the hottest reading for this week of the year since 1948. Next is 73° in 1990.
The Silos’s center stands about 3,890 ft above sea level. Within three miles the land runs from 3,790 ft to 4,820 ft, a difference of 1,030 ft: steep hill country. The highest named summit within 15 miles is High Peak, about 8,520 ft, 12 miles west.
Under the town center the state geologic map shows Gravel, from the Late Miocene to Holocene, less than 7.2 million years old.
The section below crosses 7 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 4×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Andesite, latite. Age: Late Cretaceous, 72 to 84 million years old. About 6 mi of the line.
Age: Late Miocene to Holocene, less than 7.2 million years old. About 4 mi of the line.
Conglomerate, sandstone, siltstone. Age: Early Miocene to Pliocene, 2.6 to 20 million years old. About 3 mi of the line.
Age: Pleistocene to Holocene, less than 1.8 million years old. About 3 mi of the line.
Age: Cretaceous, 66 to 145 million years old. About 2 mi of the line.
Granitic. Age: Cretaceous, 66 to 145 million years old. About 0.9 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 1 smaller unit 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 The Silos reaches the Gulf of America by way of Whitehorse Creek, the Missouri and the Mississippi: about 3,430 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 The Silos; river miles along the main stem, rounded.
The Silos has a cold semi-arid climate. Summer afternoons average 83° in July; winter nights fall to about 14° in January. A normal year brings about 24 inches of snow; with the rain, that comes to about 11 inches of water.
On November 14 The Silos normally reaches 44° and falls to 23°. The record high is 67°, in 2021; the record low −11°, in 1959. The most rain on this date, 0.15 in, fell in 1978.
Normals 1991–2020 and records since 1948 at Townsend 3 SE, 9 miles southeast. NOAA, through RCC-ACIS.
