The Potomac Park 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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79° on Nov. 15, 2011, the hottest reading for this week of the year since 1974. Next is 78° in 2020.
Potomac Park’s center stands about 780 ft above sea level. Within three miles the land runs from 580 ft to 1,780 ft, a difference of 1,200 ft: steep hill country. The highest named summit within 15 miles is Sampson Rock, about 2,940 ft, 9 miles northwest.
Under the town center the state geologic map shows Clinton Group, including Rochester Shale (shale, sandstone), from the Silurian, 422 to 445 million years old.
The section below crosses 17 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 8×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Claystone, limestone. Age: Carboniferous, 299 to 324 million years old. About 4 mi of the line.
Shale. Age: Devonian, 359 to 422 million years old. About 4 mi of the line.
Quartzite. Age: Devonian, 359 to 422 million years old. About 4 mi of the line.
Claystone, shale. Age: Carboniferous, 299 to 324 million years old. About 2 mi of the line.
Sandstone, shale. Age: Carboniferous, 299 to 324 million years old. About 2 mi of the line.
Shale, sandstone. 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. 11 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 Potomac Park reaches Chesapeake Bay and the Atlantic Ocean by way of the North Branch Potomac and the Potomac: about 320 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Potomac Park; river miles along the main stem, rounded.
Potomac Park has a hot-summer humid continental climate. Summer afternoons average 87° in July; winter nights fall to about 23° in January. A normal year brings about 29 inches of snow; with the rain, that comes to about 39 inches of water.
On November 14 Potomac Park normally reaches 54° and falls to 34°. The record high is 71°, in 1993; the record low 13°, in 1986. The most rain on this date, 0.72 in, fell in 1997.
Normals 1991–2020 and records since 1974 at Cumberland 2, 3 miles northeast. NOAA, through RCC-ACIS.
