The Allagash 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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Allagash’s center stands about 630 ft above sea level. Within three miles the land runs from 580 ft to 1,410 ft, a difference of 830 ft: hilly country. The highest named summit within 15 miles is Rocky Mountain, about 2,000 ft, 14 miles west-northwest.
Under the town center the state geologic map shows Devonian Seboomook Formation (mudstone, sandstone), from the Early Devonian, 410 to 414 million years old.
The section below crosses 5 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 14×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Mudstone, sandstone. Age: Early Devonian, 410 to 414 million years old. About 21 mi of the line.
Mudstone. Age: Devonian, 359 to 422 million years old. About 2 mi of the line.
Granodiorite. Age: Devonian, 359 to 422 million years old. About 0.3 mi of the line.
Syenite, monzodiorite. Age: Devonian, 359 to 422 million years old. About 0.3 mi of the line.
Quartzite. Age: Devonian, 359 to 422 million years old. About 0.1 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale.
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 Allagash reaches the Bay of Fundy and the Atlantic Ocean by way of the Allagash and the Saint John: about 300 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Allagash; river miles along the main stem, rounded.
