The West Cornwall 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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74° on Nov. 11, 2020, the hottest reading for this week of the year since 1948. Next is 73° in 1993.
West Cornwall’s center stands about 550 ft above sea level. Within three miles the land runs from 510 ft to 1,430 ft, a difference of 920 ft: steep hill country. The highest named summit within 15 miles is Mount Frissell, about 2,440 ft, 14 miles north-northwest.
Under the town center the state geologic map shows Layered gneiss, from the Mesoproterozoic, 1 to 1.6 billion 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 13×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Gneiss. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 7 mi of the line.
Amphibolite, gneiss. Age: Cambrian, 487 to 542 million years old. About 4 mi of the line.
Gneiss. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 4 mi of the line.
Schist. Age: Cambrian, 487 to 542 million years old. About 3 mi of the line.
Marble. Age: Cambrian to Early Ordovician, 471 to 542 million years old. About 2 mi of the line.
Gneiss, quartzite. Age: Early Cambrian, 521 to 542 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. 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 West Cornwall reaches Long Island Sound and the Atlantic Ocean by way of Ivy Brook and the Housatonic: about 70 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of West Cornwall; river miles along the main stem, rounded.
West Cornwall has a warm-summer humid continental climate. Summer afternoons average 82° in July; winter nights fall to about 15° in January. A normal year brings about 59 inches of snow; with the rain, that comes to about 54 inches of water.
On November 14 West Cornwall normally reaches 50° and falls to 29°. The record high is 64°, in 2010; the record low 11°, in 2019. The most rain on this date, 0.93 in, fell in 1970.
Normals 1991–2020 and records since 1948 at Bakersville, 18 miles east, 140 ft higher. NOAA, through RCC-ACIS.
