The Spring Valley 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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−7° on Nov. 15, 1959, the coldest reading for this week of the year since 1897. Next is −1° in 2019.
Spring Valley’s center stands about 920 ft above sea level. Within three miles the land runs from 790 ft to 1,020 ft, a difference of 230 ft: rolling country. The highest named summit within 15 miles is Liberty Pole Hill, about 1,110 ft, 13 miles north-northwest.
Under the town center the state geologic map shows Ancell Group (sandstone), from the Ordovician, 445 to 487 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 59×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Sandstone. Age: Ordovician, 445 to 487 million years old. About 16 mi of the line.
Dolostone. Age: Ordovician, 445 to 487 million years old. About 6 mi of the line.
Dolostone. Age: Early Ordovician, 471 to 487 million years old. About 1 mi of the line.
Dolostone, limestone. Age: Late Ordovician, 454 to 459 million years old. About 1 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 Spring Valley reaches the Gulf of America by way of Taylor Creek, the Sugar, the Pecatonica, the Rock River and the Mississippi: about 1,650 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Spring Valley; river miles along the main stem, rounded.
Spring Valley has a hot-summer humid continental climate. Summer afternoons average 83° in July; winter nights fall to about 11° in January. A normal year brings about 37 inches of snow; with the rain, that comes to about 38 inches of water.
On November 14 Spring Valley normally reaches 47° and falls to 28°. The record high is 71°, in 1999; the record low 3°, in 1986. The most rain on this date, 1.25 in, fell in 1899.
Normals 1991–2020 and records since 1897 at Brodhead Wwtp, 5 miles southwest, 140 ft lower. NOAA, through RCC-ACIS.
