The Chapman 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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75° on Nov. 11, 2020, the hottest reading for this week of the year since 1982. Next is 68° in 2012.
Chapman’s center stands about 1,910 ft above sea level. Within three miles the land runs from 900 ft to 2,100 ft, a difference of 1,200 ft: steep hill country. The highest named summit within 15 miles is Bean Hill, about 2,400 ft, 15 miles north.
The section below crosses 4 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.
Sandstone, siltstone. Age: Devonian to Carboniferous, 324 to 422 million years old. About 10 mi of the line.
Sandstone, siltstone, shale. Age: Late Devonian, 359 to 384 million years old. About 7 mi of the line.
Sandstone. Age: Carboniferous, 324 to 359 million years old. About 7 mi of the line.
Sandstone, conglomerate. Age: Carboniferous, 299 to 324 million years old. About 0.4 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 Chapman reaches Chesapeake Bay and the Atlantic Ocean by way of Young Womans Creek, Left Branch Young Womans Creek, the West Branch Susquehanna and the Susquehanna: about 230 river miles.
Lake on the way: Lake Aldred.
95 miles of the trip are on the West Branch Susquehanna.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Chapman; river miles along the main stem, rounded.
Chapman has a cold desert climate. Summer afternoons average 82° in July; winter nights fall to about 18° in January. Barely 0.0 inches of rain fall in a normal year.
Normals 1991–2020 and records since 1982 at Alvin R Bush Dam, 14 miles west-southwest, 980 ft lower. NOAA, through RCC-ACIS.
