The Penn 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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77° on Nov. 15, 1973, the hottest reading for this week of the year since 1910. Next is 75° in 1993.
Penn’s center stands about 640 ft above sea level. Within three miles the land runs from 600 ft to 1,370 ft, a difference of 770 ft: hilly country. The highest named summit within 15 miles is Bowers Mountain, about 2,100 ft, 15 miles north-northwest.
Under the town center the state geologic map shows Waynesboro Formation (shale, sandstone), from the Cambrian, 487 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 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.
Quartzite. Age: Cambrian, 487 to 542 million years old. About 6 mi of the line.
Shale. Age: Ordovician, 445 to 487 million years old. About 4 mi of the line.
Quartzite. Age: Cambrian, 487 to 542 million years old. About 3 mi of the line.
Limestone. Age: Ordovician, 445 to 487 million years old. About 2 mi of the line.
Quartzite. Age: Cambrian, 487 to 542 million years old. About 2 mi of the line.
Limestone. Age: Cambrian, 487 to 542 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. 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 Penn reaches Chesapeake Bay and the Atlantic Ocean by way of Yellow Breeches Creek and the Susquehanna: about 110 river miles.
Lake on the way: Lake Aldred.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Penn; river miles along the main stem, rounded.
Penn has a hot-summer humid continental climate. Summer afternoons average 88° in July; winter nights fall to about 22° in January. A normal year brings about 34 inches of snow; with the rain, that comes to about 42 inches of water.
On November 14 Penn normally reaches 54° and falls to 34°. The record high is 73°, in 1989; the record low 14°, in 1986. The most rain on this date, 1.88 in, fell in 1995.
Normals 1991–2020 and records since 1910 at Shippensburg, 10 miles west-southwest. NOAA, through RCC-ACIS.
