The Chatham 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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79° on Nov. 17, 2016, the hottest reading for this week of the year since 1879. Next is 78° in 1955.
Chatham’s center stands about 610 ft above sea level. Within three miles the land runs from 550 ft to 640 ft, a difference of 90 ft: gently rolling country.
Under the town center the state geologic map shows Shelburn-Patoka Formations undivided (shale, limestone), from the Late Pennsylvanian, 304 to 307 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, limestone. Age: Late Pennsylvanian, 304 to 307 million years old. About 20 mi of the line.
Shale, sandstone, limestone. Age: Late Pennsylvanian, 304 to 307 million years old. About 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 Chatham reaches the Gulf of America by way of Lake Springfield, Sugar Creek, the Sangamon, the Illinois and the Mississippi: about 1,380 river miles.
Lake on the way: Lake Springfield.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Chatham; river miles along the main stem, rounded.
Chatham has a hot-summer humid continental climate. Summer afternoons average 87° in July; winter nights fall to about 20° in January. A normal year brings about 22 inches of snow; with the rain, that comes to about 38 inches of water.
On November 14 Chatham normally reaches 53° and falls to 35°. The record high is 78°, in 2025; the record low 12°, in 1940. The most rain on this date, 0.91 in, fell in 1993.
Normals 1991–2020 and records since 1879 from the Springfield Area threaded record (Springfield Abraham Lincoln Capital Airport, 12 miles north). NOAA, through RCC-ACIS.
