The Putnam 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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75° on Nov. 11, 2020, the hottest reading for this week of the year since 1962. Next is 74° in 1993.
Putnam’s center stands about 270 ft above sea level. Within three miles the land runs from 230 ft to 600 ft, a difference of 370 ft: rolling country. The highest named summit within 15 miles is Lead Mine Hill, about 1,220 ft, 15 miles west-northwest.
Under the town center the state geologic map shows Tatnic Hill Formation (gneiss, schist), from the Neoproterozoic, 542 to 1,000 million years old.
The section below crosses 15 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 23×. 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, amphibolite. Age: Neoproterozoic, 542 to 1,000 million years old. About 5 mi of the line.
Schist, calc-silicate-rock. Age: Neoproterozoic, 542 to 1,000 million years old. About 4 mi of the line.
Granofels, schist. Age: Neoproterozoic, 542 to 1,000 million years old. About 3 mi of the line.
Gneiss. Age: Ordovician to Middle Ordovician, 459 to 487 million years old. About 2 mi of the line.
Granofels, schist. Age: Cambrian to Ordovician, 445 to 542 million years old. About 2 mi of the line.
Gneiss. Age: Devonian, 359 to 422 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. 9 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 Putnam reaches Long Island Sound and the Atlantic Ocean by way of Culver Brook, the Quinebaug, the Shetucket and the Thames: about 55 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Putnam; river miles along the main stem, rounded.
Putnam 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 38 inches of snow; with the rain, that comes to about 50 inches of water.
On November 14 Putnam normally reaches 51° and falls to 31°. The record high is 65°, in 2010; the record low 10°, in 1986. The most rain on this date, 1.06 in, fell in 1988.
Normals 1991–2020 and records since 1962 at West Thompson Lake, 2 miles north. NOAA, through RCC-ACIS.
