The Cairnbrook 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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Cairnbrook’s center stands about 2,250 ft above sea level. Within three miles the land runs from 2,050 ft to 2,710 ft, a difference of 660 ft: hilly country. The highest named summit within 15 miles is Round Top, about 2,800 ft, 13 miles northeast.
Under the town center the state geologic map shows Allegheny Formation (sandstone), from the Carboniferous, 299 to 324 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 11×. 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. Age: Carboniferous, 299 to 324 million years old. About 8 mi of the line.
Shale. Age: Carboniferous, 299 to 324 million years old. About 5 mi of the line.
Sandstone, conglomerate. Age: Carboniferous, 299 to 324 million years old. About 3 mi of the line.
Black-shale. Age: Early Devonian to Middle Devonian, 384 to 422 million years old. About 2 mi of the line.
Shale, clastic. Age: Carboniferous, 299 to 324 million years old. About 2 mi of the line.
Sandstone, siltstone, shale. Age: Late Devonian, 359 to 384 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. 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 Cairnbrook reaches the Gulf of America by way of Dark Shade Creek, Shade Creek, the Stonycreek, the Conemaugh, the Kiskiminetas, the Allegheny, the Ohio and the Mississippi: about 2,080 river miles.
970 miles of the trip are on the Ohio.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Cairnbrook; river miles along the main stem, rounded.
