The Calhoun 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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84° on Nov. 11, 2020, the hottest reading for this week of the year since 1948. Next is 82° in 1958.
Calhoun’s center stands about 660 ft above sea level. Within three miles the land runs from 610 ft to 830 ft, a difference of 220 ft: rolling country. The highest named summit within 15 miles is Johns Mountain, about 1,890 ft, 12 miles northwest.
The section below crosses 9 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 15×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Limestone, shale. Age: Cambrian, 487 to 542 million years old. About 8 mi of the line.
Dolostone. Age: Cambrian to Ordovician, 445 to 542 million years old. About 7 mi of the line.
Shale. Age: Carboniferous, 324 to 359 million years old. About 4 mi of the line.
Limestone. Age: Cambrian, 487 to 497 million years old. About 1 mi of the line.
Limestone, sandstone. Age: Ordovician, 445 to 487 million years old. About 1 mi of the line.
Black-shale, chert. Age: Devonian to Carboniferous, 324 to 422 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. 3 smaller units along the line are not listed.
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 Calhoun reaches Mobile Bay and the Gulf of America by way of Oothkalooga Creek, the Oostanaula, the Coosa, the Alabama and the Mobile: about 680 river miles.
Lake on the way: Lay Lake.
310 miles of the trip are on the Alabama.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Calhoun; river miles along the main stem, rounded.
Calhoun has a humid subtropical climate. Summer afternoons average 91° in July; winter nights fall to about 32° in January. About 51 inches of rain fall in a normal year.
On November 14 Calhoun normally reaches 64° and falls to 39°. The record high is 80°, in 1955; the record low 20°, in 2013. The most rain on this date, 1.35 in, fell in 1957.
Normals 1991–2020 and records since 1948 at Rome R B Russell Airport, 16 miles southwest. NOAA, through RCC-ACIS.
