The Carroll 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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−4° on Nov. 17, 2019, the coldest reading for this week of the year since 1996. Next is −1° in 1996.
Carroll’s center stands about 1,450 ft above sea level. Within three miles the land runs from 1,160 ft to 3,170 ft, a difference of 2,010 ft: mountain country. The highest named summit within 15 miles is Mount Washington, about 6,260 ft, 12 miles east.
Under the town center the state geologic map shows Biotite granite, from the Late Ordovician, 445 to 459 million years old.
The section below crosses 8 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 4×. 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: Late Ordovician, 445 to 459 million years old. About 8 mi of the line.
Granodiorite. Age: Late Ordovician, 445 to 459 million years old. About 4 mi of the line.
Granite. Age: Late Ordovician, 445 to 459 million years old. About 3 mi of the line.
Metasandstone. Age: Silurian, 434 to 445 million years old. About 3 mi of the line.
Granite. Age: Early Devonian to Late Devonian, 359 to 422 million years old. About 2 mi of the line.
Metagraywacke. Age: Early Devonian, 410 to 414 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. 2 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 Carroll reaches Long Island Sound and the Atlantic Ocean by way of Black Brook, the Ammonoosuc and the Connecticut: about 310 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Carroll; river miles along the main stem, rounded.
Carroll has a warm-summer humid continental climate. Summer afternoons average 80° in July; winter nights fall to about 5° in January. About 37 inches of rain fall in a normal year.
Normals 1991–2020 and records since 1996 at Whitefield Mount Washington Regional Airport, 5 miles north, 400 ft lower. NOAA, through RCC-ACIS.
