The Big Rock 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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85° on Nov. 15, 1993, the hottest reading for this week of the year since 1942. Next is 80° in 1989.
Big Rock’s center stands about 930 ft above sea level. Within three miles the land runs from 900 ft to 2,060 ft, a difference of 1,160 ft: steep hill country. The highest named summit within 15 miles is Skeet Rock Knob, about 3,000 ft, 13 miles west-southwest.
Under the town center the state geologic map shows Norton Formation (shale, siltstone), from the Carboniferous, 299 to 324 million years old.
The section below crosses 3 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 12×. 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, siltstone. Age: Carboniferous, 299 to 324 million years old. About 10 mi of the line.
Shale, siltstone. Age: Carboniferous, 299 to 324 million years old. About 10 mi of the line.
Sandstone, shale, siltstone. Age: Carboniferous, 299 to 324 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 Big Rock reaches the Gulf of America by way of the Levisa Fork, the Ohio and the Mississippi: about 1,790 river miles.
970 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Big Rock; river miles along the main stem, rounded.
Big Rock has a humid subtropical climate. Summer afternoons average 83° in July; winter nights fall to about 24° in January. A normal year brings about 16 inches of snow; with the rain, that comes to about 47 inches of water.
On November 14 Big Rock normally reaches 57° and falls to 32°. The record high is 80°, in 1989; the record low 14°, in 2019. The most rain on this date, 0.52 in, fell in 1951.
Normals 1991–2020 and records since 1942 at Grundy, 7 miles southeast, 230 ft higher. NOAA, through RCC-ACIS.
