The Harrison 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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81° on Nov. 12, 1989, the hottest reading for this week of the year since 1879. Next is 80° in 1958.
Harrison’s center stands about 750 ft above sea level. Within three miles the land runs from 670 ft to 1,030 ft, a difference of 360 ft: rolling country. The highest named summit within 15 miles is Round Knob, about 2,030 ft, 13 miles west-northwest.
Under the town center the state geologic map shows Knox Group, including Newala Formation, Mascot Dolomite, Kingsport Formation, Longview Dolomite, Chepultepec Dolomite, and Copper Ridge Dolomite (dolostone, limestone), from the Cambrian to Ordovician, 445 to 542 million years old.
The section below crosses 13 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 14×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Dolostone, limestone. Age: Cambrian to Ordovician, 445 to 542 million years old. About 9 mi of the line.
Limestone. Age: Ordovician, 445 to 487 million years old. About 3 mi of the line.
Conglomerate. Age: Carboniferous, 299 to 324 million years old. About 2 mi of the line.
Limestone. Age: Carboniferous, 324 to 359 million years old. About 2 mi of the line.
Dolostone, limestone. Age: Ordovician, 445 to 487 million years old. About 2 mi of the line.
Shale, limestone. Age: Silurian, 422 to 445 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. 7 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 Harrison reaches the Gulf of America by way of the Tennessee, the Ohio and the Mississippi: about 1,500 river miles.
Lakes on the way: Guntersville Lake, White Lake (historical), Pickwick Lake and Cummings Lake.
970 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Harrison; river miles along the main stem, rounded.
Harrison has a humid subtropical climate. Summer afternoons average 91° in July; winter nights fall to about 32° in January. About 55 inches of rain fall in a normal year, with about 4 inches of snow.
On November 14 Harrison normally reaches 62° and falls to 40°. The record high is 79°, in 1999; the record low 18°, in 1969. The most rain on this date, 2.47 in, fell in 1929.
Normals 1991–2020 and records since 1879 from the Chattanooga Area threaded record (Chattanooga Airport, 7 miles south-southwest). NOAA, through RCC-ACIS.
