The Walnut 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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−1° on Nov. 12, 2019, the coldest reading for this week of the year since 1893. Next is 0° in 1996.
Walnut’s center stands about 710 ft above sea level. Within three miles the land runs from 630 ft to 830 ft, a difference of 200 ft: gently rolling country.
Under the town center the state geologic map shows Silurian System undivided (dolostone, limestone), from the Silurian, 422 to 445 million years old.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 64×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Dolostone, limestone. Age: Silurian, 422 to 445 million years old. About 24 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 Walnut reaches the Gulf of America by way of the Green River, the Rock River and the Mississippi: about 1,510 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Walnut; river miles along the main stem, rounded.
Walnut has a hot-summer humid continental climate. Summer afternoons average 83° in July; winter nights fall to about 13° in January. A normal year brings about 36 inches of snow; with the rain, that comes to about 37 inches of water.
On November 14 Walnut normally reaches 48° and falls to 30°. The record high is 74°, in 1999; the record low 0°, in 1996. The most rain on this date, 1.83 in, fell in 1926.
Normals 1991–2020 and records since 1893 at Walnut, here. NOAA, through RCC-ACIS.
