The Delavan 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° on Nov. 17, 1959, the coldest reading for this week of the year since 1883. Next is 5° in 1986.
Delavan’s center stands about 610 ft above sea level. Within three miles the land runs from 530 ft to 680 ft, a difference of 150 ft: gently rolling country.
Under the town center the state geologic map shows Carbondale Formation (shale, sandstone, coal), from the Middle Pennsylvanian to Late Pennsylvanian, 304 to 315 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 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.
Shale, sandstone, coal. Age: Middle Pennsylvanian to Late Pennsylvanian, 304 to 315 million years old. About 24 mi of the line.
Shale, limestone. Age: Late Pennsylvanian, 304 to 307 million years old. About 0.5 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 Delavan reaches the Gulf of America by way of Crane Creek, the Mackinaw, the Illinois and the Mississippi: about 1,370 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Delavan; river miles along the main stem, rounded.
Delavan has a hot-summer humid continental climate. Summer afternoons average 86° in July; winter nights fall to about 18° in January. A normal year brings about 26 inches of snow; with the rain, that comes to about 38 inches of water.
On November 14 Delavan normally reaches 52° and falls to 34°. The record high is 75°, in 1971; the record low 8°, in 1940. The most rain on this date, 1.57 in, fell in 1926.
Normals 1991–2020 and records since 1883 from the Peoria Area threaded record (General Wayne A. Downing International Airport, 22 miles north-northwest). NOAA, through RCC-ACIS.
