The Lake Pocotopaug 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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5° on Nov. 17, 1996, the coldest reading for this week of the year since 1904. Next is 6° in 1924.
Lake Pocotopaug’s center stands about 460 ft above sea level. Within three miles the land runs from 340 ft to 900 ft, a difference of 560 ft: hilly country. The highest named summit within 15 miles is John Tom Hill, about 930 ft, 8 miles north-northeast.
Under the town center the state geologic map shows Monson Gneiss (gneiss, amphibolite), from the Early Ordovician to Middle Ordovician, 459 to 487 million years old.
The section below crosses 11 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 22×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Schist, calc-silicate-rock. Age: Neoproterozoic, 542 to 1,000 million years old. About 9 mi of the line.
Arkose, siltstone. Age: Early Jurassic, 175 to 202 million years old. About 5 mi of the line.
Gneiss. Age: Middle Ordovician, 459 to 471 million years old. About 3 mi of the line.
Schist, gneiss. Age: Cambrian to Ordovician, 445 to 542 million years old. About 2 mi of the line.
Siltstone, shale. Age: Early Jurassic, 175 to 202 million years old. About 1 mi of the line.
Gneiss, amphibolite. Age: Early Ordovician to Middle Ordovician, 459 to 487 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. 5 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 Lake Pocotopaug reaches Long Island Sound and the Atlantic Ocean by way of Pocotopaug Creek, Pine Brook, the Salmon and the Connecticut: about 30 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Lake Pocotopaug; river miles along the main stem, rounded.
Lake Pocotopaug has a hot-summer humid continental climate. Summer afternoons average 85° in July; winter nights fall to about 20° in January. About 43 inches of rain fall in a normal year.
On November 14 Lake Pocotopaug normally reaches 53° and falls to 35°. The record high is 71°, in 1959; the record low 15°, in 1996. The most rain on this date, 1.07 in, fell in 1940.
Normals 1991–2020 and records since 1904 at Hartford Brainard Field, 12 miles northwest, 440 ft lower. NOAA, through RCC-ACIS.
