The Machias 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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Machias’s center stands about 90 ft above sea level. Within three miles the land runs from 0 ft to 340 ft, a difference of 340 ft: rolling country. The highest named summit within 15 miles is Peaked Mountain, about 540 ft, 12 miles west-northwest.
Under the town center the state geologic map shows Silurian Dennys Formation, mafic to felsic volcanic rock member (mafic-volcanic, felsic-volcanic), from the Silurian, 422 to 445 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 49×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Granite. Age: Devonian, 359 to 422 million years old. About 8 mi of the line.
Age: Devonian, 359 to 422 million years old. About 3 mi of the line.
Mafic-volcanic, felsic-volcanic. Age: Silurian, 422 to 445 million years old. About 3 mi of the line.
Shale. Age: Silurian, 422 to 445 million years old. About 2 mi of the line.
Gabbro, diorite, ultramafic. Age: Devonian, 359 to 422 million years old. About 2 mi of the line.
Basalt. Age: Devonian, 359 to 422 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 Machias reaches the Atlantic Ocean by way of the Machias: about 2 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Machias; river miles along the main stem, rounded.
