The Mound City 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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76° on Nov. 15, 1953, the hottest reading for this week of the year since 1911. Next is 71° in 2005.
Mound City’s center stands about 1,730 ft above sea level. Within three miles the land runs from 1,680 ft to 1,830 ft, a difference of 150 ft: gently rolling country.
Under the town center the state geologic map shows Pierre Shale (shale, bentonite), from the Late Cretaceous, 66 to 100 million years old.
The section below crosses 2 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 39×. 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, bentonite. Age: Late Cretaceous, 66 to 100 million years old. About 18 mi of the line.
Sandstone, siltstone. Age: Late Cretaceous, 66 to 100 million years old. About 5 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 Mound City reaches the Gulf of America by way of Spring Creek, the Missouri and the Mississippi: about 2,420 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 Mound City; river miles along the main stem, rounded.
Mound City has a hot-summer humid continental climate. Summer afternoons average 87° in July; winter nights fall to about 6° in January. A normal year brings about 31 inches of snow; with the rain, that comes to about 18 inches of water.
On November 14 Mound City normally reaches 45° and falls to 23°. The record high is 70°, in 2015; the record low −18°, in 1940. The most rain on this date, 0.80 in, fell in 1928.
Normals 1991–2020 and records since 1911 from the Mobridge Area threaded record (Mobridge Municipal Airport, 20 miles southwest). NOAA, through RCC-ACIS.
