The Colebrook 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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−8° on Nov. 17, 2019, the coldest reading for this week of the year since 1960. Next is −4° in 2018.
Colebrook’s center stands about 1,030 ft above sea level. Within three miles the land runs from 1,000 ft to 2,830 ft, a difference of 1,830 ft: steep hill country. The highest named summit within 15 miles is Bunnell Mountain, about 3,720 ft, 7 miles south.
Under the town center the state geologic map shows Frontenac Formation (metasandstone), from the Silurian to Devonian, 359 to 445 million years old.
The section below crosses 9 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 8×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Metagraywacke, slate. Age: Silurian, 422 to 445 million years old. About 7 mi of the line.
Metasandstone. Age: Silurian to Devonian, 359 to 445 million years old. About 4 mi of the line.
Granite. Age: Middle Jurassic to Late Jurassic, 145 to 175 million years old. About 3 mi of the line.
Phyllite, metasandstone. Age: Early Devonian, 394 to 422 million years old. About 2 mi of the line.
Syenite. Age: Jurassic, 145 to 202 million years old. About 2 mi of the line.
Diorite. Age: Jurassic, 145 to 202 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. 3 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 Colebrook reaches Long Island Sound and the Atlantic Ocean by way of the Mohawk and the Connecticut: about 360 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Colebrook; river miles along the main stem, rounded.
Colebrook has a warm-summer humid continental climate. Summer afternoons average 77° in July; winter nights fall to about 0° in January. A normal year brings about 81 inches of snow; with the rain, that comes to about 41 inches of water.
On November 14 Colebrook normally reaches 42° and falls to 22°. The record high is 64°, in 1989; the record low −6°, in 2019. The most rain on this date, 0.60 in, fell in 1975.
Normals 1991–2020 and records since 1960 at Colebrook 3 SW, 3 miles southwest. NOAA, through RCC-ACIS.
