The Thompson 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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1° on Nov. 16, 1908, the coldest reading for this week of the year since 1899. Next is 9° in 1933.
Thompson’s center stands about 770 ft above sea level. Within three miles the land runs from 510 ft to 1,550 ft, a difference of 1,040 ft: steep hill country. The highest named summit within 15 miles is Big Mountain, about 2,460 ft, 15 miles northeast.
The section below crosses 16 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 11×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Sandstone, siltstone, shale. Age: Late Devonian, 359 to 384 million years old. About 5 mi of the line.
Black-shale. Age: Early Devonian to Middle Devonian, 384 to 422 million years old. About 3 mi of the line.
Siltstone, shale. Age: Late Devonian, 359 to 384 million years old. About 3 mi of the line.
Sandstone. Age: Late Devonian, 359 to 384 million years old. About 2 mi of the line.
Shale, siltstone. Age: Devonian to Late Devonian, 374 to 422 million years old. About 2 mi of the line.
Shale. Age: Devonian, 359 to 422 million years old. About 2 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 10 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 Thompson reaches Chesapeake Bay and the Atlantic Ocean by way of Licking Creek and the Potomac: about 260 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Thompson; river miles along the main stem, rounded.
Thompson has a humid subtropical climate. Summer afternoons average 87° in July; winter nights fall to about 25° in January. About 36 inches of rain fall in a normal year.
On November 14 Thompson normally reaches 55° and falls to 38°. The record high is 75°, in 1989; the record low 10°, in 1920. The most rain on this date, 1.91 in, fell in 1995.
Normals 1991–2020 and records since 1899 from the Hagerstown Area threaded record (Hagerstown Regional Airport, 21 miles east-southeast). NOAA, through RCC-ACIS.
