The Dedham 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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68° on Nov. 11, 2020, the hottest reading for this week of the year since 1925. Next is 68° in 2022.
Dedham’s center stands about 990 ft above sea level. Within three miles the land runs from 150 ft to 970 ft, a difference of 820 ft: hilly country. The highest named summit within 15 miles is Bald Mountain, about 1,260 ft, 4 miles southwest.
Under the town center the state geologic map shows Devonian granite, from the Devonian, 359 to 422 million years old.
The section below crosses 4 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 17×. 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. Age: Devonian, 359 to 422 million years old. About 19 mi of the line.
Granite. Age: Devonian, 359 to 422 million years old. About 3 mi of the line.
Sandstone, limestone. Age: Ordovician to Devonian, 359 to 487 million years old. About 1 mi of the line.
Slate, schist, quartzite. Age: Middle Ordovician to Late Ordovician, 450 to 470 million years old. About 0.5 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale.
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 Dedham reaches the Atlantic Ocean by way of Green Lake, Graham Lake and the Union: about 20 river miles.
Lakes on the way: Graham Lake and Green Lake.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Dedham; river miles along the main stem, rounded.
Dedham has a warm-summer humid continental climate. Summer afternoons average 80° in July; winter nights fall to about 9° in January. A normal year brings about 75 inches of snow; with the rain, that comes to about 42 inches of water.
On November 14 Dedham normally reaches 46° and falls to 30°. The record high is 63°, in 2005; the record low 8°, in 2019. The most rain on this date, 1.56 in, fell in 2006.
Normals 1991–2020 and records since 1925 from the Bangor Area threaded record (Bangor International Airport, 14 miles west-northwest, 840 ft lower). NOAA, through RCC-ACIS.
