The Chatham 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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77° on Nov. 11, 2020, the hottest reading for this week of the year since 1959. Next is 72° in 2022.
Chatham’s center stands about 550 ft above sea level. Within three miles the land runs from 380 ft to 2,060 ft, a difference of 1,680 ft: steep hill country. The highest named summit within 15 miles is Carter Dome, about 4,830 ft, 11 miles northwest.
Under the town center the state geologic map shows Migmatitic rocks (migmatite), from the Silurian to Devonian, 359 to 445 million years old.
The section below crosses 8 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 5×. 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: Carboniferous, 299 to 359 million years old. About 12 mi of the line.
Migmatite. Age: Silurian to Devonian, 359 to 445 million years old. About 4 mi of the line.
Granodiorite. Age: Early Devonian, 394 to 422 million years old. About 3 mi of the line.
Metagraywacke. Age: Early Devonian, 410 to 414 million years old. About 2 mi of the line.
Metasandstone. Age: Silurian, 434 to 445 million years old. About 2 mi of the line.
Quartz-syenite. Age: Jurassic, 145 to 202 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. 2 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 Chatham reaches the Atlantic Ocean by way of Province Brook, Kimball Brook, the Old Course Saco and the Saco: about 95 river miles.
80 miles of the trip are on the Saco.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Chatham; river miles along the main stem, rounded.
Chatham 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 84 inches of snow; with the rain, that comes to about 50 inches of water.
On November 14 Chatham normally reaches 47° and falls to 28°. The record high is 63°, in 1985; the record low 8°, in 1971. The most rain on this date, 0.85 in, fell in 2018.
Normals 1991–2020 and records since 1959 at North Conway, 10 miles southwest. NOAA, through RCC-ACIS.
