The Dorchester 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, 2002, the hottest reading for this week of the year since 1884. Next is 69° in 1909.
Dorchester’s center stands about 1,390 ft above sea level. Within three miles the land runs from 1,020 ft to 2,100 ft, a difference of 1,080 ft: steep hill country. The highest named summit within 15 miles is Smarts Mountain, about 3,220 ft, 6 miles northwest.
Under the town center the state geologic map shows Bethlehem Granodiorite, from the Early Devonian, 394 to 422 million 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 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.
Granodiorite. Age: Early Devonian, 394 to 422 million years old. About 7 mi of the line.
Granodiorite. Age: Early Devonian, 394 to 422 million years old. About 4 mi of the line.
Metaclastic. Age: Early Devonian, 394 to 422 million years old. About 3 mi of the line.
Granodiorite, tonalite. Age: Late Ordovician, 445 to 459 million years old. About 2 mi of the line.
Granite. Age: Late Devonian, 359 to 384 million years old. About 2 mi of the line.
Metasedimentary. Age: Early Devonian, 394 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. 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 Dorchester reaches Long Island Sound and the Atlantic Ocean by way of the Indian, the Mascoma and the Connecticut: about 250 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Dorchester; river miles along the main stem, rounded.
Dorchester has a hot-summer humid continental climate. Summer afternoons average 84° in July; winter nights fall to about 13° in January. A normal year brings about 61 inches of snow; with the rain, that comes to about 40 inches of water.
On November 14 Dorchester normally reaches 48° and falls to 31°. The record high is 66°, in 1973; the record low 6°, in 1905. The most rain on this date, 1.19 in, fell in 2007.
Normals 1991–2020 and records since 1884 at Hanover, 17 miles west-southwest, 810 ft lower. NOAA, through RCC-ACIS.
