The Brockton 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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Brockton’s center stands about 840 ft above sea level. Within three miles the land runs from 750 ft to 1,710 ft, a difference of 960 ft: steep hill country. The highest named summit within 15 miles is Bears Head, about 2,090 ft, 7 miles north.
Under the town center the state geologic map shows Llewellyn Formation (sandstone), from the Carboniferous, 299 to 324 million years old.
The section below crosses 9 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 13×. 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 9 mi of the line.
Black-shale. Age: Early Devonian to Middle Devonian, 384 to 422 million years old. About 4 mi of the line.
Sandstone. Age: Carboniferous, 299 to 324 million years old. About 3 mi of the line.
Sandstone. Age: Carboniferous, 299 to 324 million years old. About 3 mi of the line.
Shale. Age: Silurian, 422 to 445 million years old. About 3 mi of the line.
Siltstone, mudstone. 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. 3 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 Brockton reaches Delaware Bay and the Atlantic Ocean by way of the Schuylkill and the Delaware: about 190 river miles.
130 miles of the trip are on the Schuylkill.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Brockton; river miles along the main stem, rounded.
