The Swanzey 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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0° on Nov. 16, 1933, the coldest reading for this week of the year since 1893. Next is 6° in 1905.
Swanzey’s center stands about 500 ft above sea level. Within three miles the land runs from 450 ft to 1,040 ft, a difference of 590 ft: hilly country. The highest named summit within 15 miles is Monadnock Mountain, about 3,130 ft, 9 miles east.
Under the town center the state geologic map shows Granite, granodiorite, and tonalite (granite, granodiorite, tonalite), from the Late Ordovician, 445 to 459 million years old.
The section below crosses 13 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.
Granite, granodiorite, tonalite. Age: Late Ordovician, 445 to 459 million years old. About 6 mi of the line.
Granodiorite. Age: Early Devonian, 394 to 422 million years old. About 5 mi of the line.
Metaclastic. Age: Early Devonian, 394 to 422 million years old. About 3 mi of the line.
Metasedimentary. Age: Early Devonian, 394 to 422 million years old. About 2 mi of the line.
Pelitic-schist, metasandstone. Age: Silurian, 434 to 445 million years old. About 2 mi of the line.
Quartz-diorite, tonalite, granodiorite. Age: Early Devonian, 394 to 422 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. 7 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 Swanzey reaches Long Island Sound and the Atlantic Ocean by way of the South Branch Ashuelot, the Ashuelot and the Connecticut: about 170 river miles.
140 miles of the trip are on the Connecticut.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Swanzey; river miles along the main stem, rounded.
Swanzey has a warm-summer humid continental climate. Summer afternoons average 82° in July; winter nights fall to about 10° in January. A normal year brings about 60 inches of snow; with the rain, that comes to about 46 inches of water.
On November 14 Swanzey normally reaches 47° and falls to 27°. The record high is 68°, in 1989; the record low 6°, in 1905. The most rain on this date, 1.61 in, fell in 1937.
Normals 1991–2020 and records since 1893 at Keene, 5 miles north-northwest. NOAA, through RCC-ACIS.
