The Jonestown 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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Jonestown’s center stands about 750 ft above sea level. Within three miles the land runs from 660 ft to 1,700 ft, a difference of 1,040 ft: steep hill country. The highest named summit within 15 miles is Red Rock Mountain, about 2,410 ft, 13 miles north.
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 10 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 15×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Siltstone, shale. Age: Late Devonian, 359 to 384 million years old. About 11 mi of the line.
Siltstone, mudstone. Age: Late Devonian, 359 to 384 million years old. About 2 mi of the line.
Sandstone, siltstone, shale. Age: Late Devonian, 359 to 384 million years old. About 2 mi of the line.
Siltstone. Age: Late Devonian, 359 to 384 million years old. About 2 mi of the line.
Black-shale. Age: Early Devonian to Middle Devonian, 384 to 422 million years old. About 2 mi of the line.
Siltstone, sandstone. Age: Late Devonian, 359 to 384 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. 4 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 Jonestown reaches Chesapeake Bay and the Atlantic Ocean by way of Huntington Creek, Fishing Creek and the Susquehanna: about 170 river miles.
Lake on the way: Lake Aldred.
110 miles of the trip are on the Susquehanna.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Jonestown; river miles along the main stem, rounded.
