The Rio 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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76° on Nov. 11, 1964, the hottest reading for this week of the year since 1895. Next is 75° in 1949.
Rio’s center stands about 780 ft above sea level. Within three miles the land runs from 710 ft to 790 ft, a difference of 80 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 18 mi of the line.
Shale, sandstone. Age: Early Pennsylvanian to Middle Pennsylvanian, 307 to 324 million years old. About 6 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 Rio reaches the Gulf of America by way of North Henderson Creek, Henderson Creek and the Mississippi: about 1,440 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Rio; river miles along the main stem, rounded.
Rio 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 26 inches of snow; with the rain, that comes to about 39 inches of water.
On November 14 Rio normally reaches 49° and falls to 30°. The record high is 75°, in 1971; the record low 8°, in 1940. The most rain on this date, 2.34 in, fell in 1926.
Normals 1991–2020 and records since 1895 at Galesburg, 11 miles south. NOAA, through RCC-ACIS.
