The Colrain 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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Colrain’s center stands about 650 ft above sea level. Within three miles the land runs from 480 ft to 1,410 ft, a difference of 930 ft: steep hill country. The highest named summit within 15 miles is Mount Olga, about 2,420 ft, 13 miles north-northwest.
Under the town center the state geologic map shows Waits River Formation (schist), from the Early Devonian, 394 to 422 million years old.
The section below crosses 19 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 10×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Arkose, siltstone, sandstone. Age: Late Triassic, 202 to 237 million years old. About 3 mi of the line.
Schist. Age: Early Devonian, 394 to 422 million years old. About 3 mi of the line.
Schist. Age: Early Devonian, 394 to 422 million years old. About 3 mi of the line.
Schist. Age: Early Devonian, 394 to 422 million years old. About 2 mi of the line.
Sandstone, siltstone, black-shale. Age: Early Jurassic, 175 to 202 million years old. About 2 mi of the line.
Quartz-feldspar-schist. Age: Cambrian to Early Ordovician, 471 to 542 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. 13 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 Colrain reaches Long Island Sound and the Atlantic Ocean by way of the East Branch North, the Deerfield and the Connecticut: about 140 river miles.
120 miles of the trip are on the Connecticut.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Colrain; river miles along the main stem, rounded.
