The Upper Mahantongo 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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3.89 inches of rain fell in two days, the most for this week of the year since records began in 1893. The next wettest, 2.87 inches, fell in 1935.
Upper Mahantongo’s center stands about 620 ft above sea level. Within three miles the land runs from 590 ft to 1,500 ft, a difference of 910 ft: steep hill country. The highest named summit within 15 miles is Big Lick Mountain, about 1,820 ft, 5 miles south-southeast.
Under the town center the state geologic map shows Sherman Creek Member of Catskill Formation (siltstone, mudstone), from the Late Devonian, 359 to 384 million years old.
The section below crosses 6 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 16×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Shale, siltstone, sandstone. Age: Carboniferous, 324 to 359 million years old. About 7 mi of the line.
Siltstone. Age: Late Devonian, 359 to 384 million years old. About 6 mi of the line.
Sandstone, siltstone. Age: Late Devonian, 359 to 384 million years old. About 4 mi of the line.
Sandstone. Age: Carboniferous, 324 to 359 million years old. About 3 mi of the line.
Siltstone, mudstone. Age: Late Devonian, 359 to 384 million years old. About 3 mi of the line.
Sandstone. Age: Devonian to Carboniferous, 324 to 422 million years old. About 0.5 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 Upper Mahantongo reaches Chesapeake Bay and the Atlantic Ocean by way of Mahantango Creek and the Susquehanna: about 130 river miles.
Lake on the way: Lake Aldred.
65 miles of the trip are on the Susquehanna.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Upper Mahantongo; river miles along the main stem, rounded.
Upper Mahantongo has a hot-summer humid continental climate. Summer afternoons average 85° in July; winter nights fall to about 19° in January. A normal year brings about 29 inches of snow; with the rain, that comes to about 43 inches of water.
On November 14 Upper Mahantongo normally reaches 52° and falls to 32°. The record high is 68°, in 1902; the record low 14°, in 1920. The most rain on this date, 0.69 in, fell in 1988.
Normals 1991–2020 and records since 1893 at Selinsgrove Penn Valley Airport, 17 miles northwest, 180 ft lower. NOAA, through RCC-ACIS.
