The Grand Ridge 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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Mostly sunny; warmer
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75° on Nov. 11, 2022, the hottest reading for this week of the year since 1941. Next is 74° in 2020.
Grand Ridge’s center stands about 650 ft above sea level. Within three miles the land runs from 600 ft to 680 ft, a difference of 80 ft: gently rolling country.
The section below crosses 5 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 12 mi of the line.
Shale, limestone. Age: Late Pennsylvanian, 304 to 307 million years old. About 6 mi of the line.
Dolostone, limestone. Age: Late Ordovician, 454 to 459 million years old. About 2 mi of the line.
Sandstone, limestone, dolostone. Age: Middle Ordovician to Late Ordovician, 454 to 468 million years old. About 2 mi of the line.
Shale, sandstone. Age: Early Pennsylvanian to Middle Pennsylvanian, 307 to 324 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 Grand Ridge reaches the Gulf of America by way of Covel Creek, the Illinois and the Mississippi: about 1,440 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 Grand Ridge; river miles along the main stem, rounded.
Grand Ridge has a hot-summer humid continental climate. Summer afternoons average 84° in July; winter nights fall to about 14° in January. A normal year brings about 25 inches of snow; with the rain, that comes to about 39 inches of water.
Normals 1991–2020 and records since 1941 at Marseilles Lock/Dam, 8 miles north-northeast, 160 ft lower. NOAA, through RCC-ACIS.
