The Thornton 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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3.35 inches of rain fell in two days, the most for this week of the year since records began in 1952. The next wettest, 2.16 inches, fell in 2003.
Thornton’s center stands about 630 ft above sea level. Within three miles the land runs from 470 ft to 680 ft, a difference of 210 ft: 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.
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.
Dolostone, limestone. Age: Silurian, 422 to 445 million years old. About 17 mi of the line.
Limestone, dolostone. Age: Devonian, 359 to 422 million years old. About 4 mi of the line.
Limestone, dolostone. Age: Silurian, 422 to 445 million years old. About 3 mi of the line.
Black-shale. Age: Devonian, 359 to 422 million years old. About 0.4 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 Thornton reaches the Gulf of America by way of Thorn Creek, the East Arm Little Calumet, the Calumet Sag Channel, the Chicago Sanitary and Ship Canal, the Des Plaines, the Illinois and the Mississippi: about 1,530 river miles.
Lake on the way: Peoria Lake.
1,190 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Thornton; river miles along the main stem, rounded.
Thornton has a hot-summer humid continental climate. Summer afternoons average 84° in July; winter nights fall to about 15° in January. A normal year brings about 28 inches of snow; with the rain, that comes to about 42 inches of water.
On November 14 Thornton normally reaches 49° and falls to 32°. The record high is 73°, in 1971; the record low 5°, in 1986. The most rain on this date, 1.03 in, fell in 1957.
Normals 1991–2020 and records since 1952 at Park Forest Water, 6 miles southwest. NOAA, through RCC-ACIS.
