The Antrim 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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Antrim’s center stands about 710 ft above sea level. Within three miles the land runs from 600 ft to 1,330 ft, a difference of 730 ft: hilly country. The highest named summit within 15 miles is Monadnock Mountain, about 3,130 ft, 15 miles southwest.
Under the town center the state geologic map shows Kinsman Granodiorite, from the Early Devonian, 394 to 422 million years old.
The section below crosses 7 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.
Granodiorite. Age: Early Devonian, 394 to 422 million years old. About 11 mi of the line.
Quartz-diorite, tonalite, granodiorite. Age: Early Devonian, 394 to 422 million years old. About 9 mi of the line.
Pelitic-schist, metasandstone. Age: Silurian, 434 to 445 million years old. About 2 mi of the line.
Granofels, calc-silicate-rock, pelitic-schist. Age: Silurian, 422 to 428 million years old. About 1 mi of the line.
Quartzite, metasedimentary. Age: Silurian, 422 to 445 million years old. About 1 mi of the line.
Schist, granofels. Age: Silurian, 425 to 434 million years old. About 0.6 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 1 smaller unit 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 Antrim reaches the Atlantic Ocean by way of Great Brook, the Contoocook and the Merrimack: about 150 river miles.
100 miles of the trip are on the Merrimack.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Antrim; river miles along the main stem, rounded.
