The Clarksville 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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71° on Nov. 11, 2020, the hottest reading for this week of the year since 1918. Next is 67° in 2002.
Clarksville’s center stands about 1,750 ft above sea level. Within three miles the land runs from 1,370 ft to 2,210 ft, a difference of 840 ft: hilly country. The highest named summit within 15 miles is Stub Hill, about 3,630 ft, 13 miles east-northeast.
Under the town center the state geologic map shows Frontenac Formation, undivided (metagraywacke, slate), from the Silurian, 422 to 445 million years old.
The section below crosses 12 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 9×. 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 9 mi of the line.
Pelitic-schist, quartzite. Age: Cambrian to Early Ordovician, 471 to 497 million years old. About 3 mi of the line.
Metasandstone. Age: Silurian to Devonian, 359 to 445 million years old. About 3 mi of the line.
Granofels, pelitic-schist. Age: Silurian, 422 to 445 million years old. About 2 mi of the line.
Metavolcanic. Age: Silurian, 422 to 445 million years old. About 2 mi of the line.
Metabasalt. Age: Silurian, 422 to 445 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. 6 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 Clarksville reaches Long Island Sound and the Atlantic Ocean by way of Labrador Brook and the Connecticut: about 380 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Clarksville; river miles along the main stem, rounded.
Clarksville has a warm-summer humid continental climate. Summer afternoons average 75° in July; winter nights fall to about 0° in January. A normal year brings about 143 inches of snow; with the rain, that comes to about 47 inches of water.
On November 14 Clarksville normally reaches 40° and falls to 24°. The record high is 59°, in 2010; the record low −1°, in 2019. The most rain on this date, 0.72 in, fell in 1948.
Normals 1991–2020 and records since 1918 at First Connecticut Lake, 5 miles north-northeast, 100 ft lower. NOAA, through RCC-ACIS.
