The Andover 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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70° on Nov. 11, 2020, the hottest reading for this week of the year since 1940. Next is 65° in 2022.
Andover’s center stands about 1,160 ft above sea level. Within three miles the land runs from 930 ft to 2,230 ft, a difference of 1,300 ft: steep hill country. The highest named summit within 15 miles is Peru Peak, about 3,420 ft, 12 miles west.
Under the town center the state geologic map shows Stowe Formation - schist and phyllite member (phyllite, muscovite-schist), from the Neoproterozoic to Cambrian, 487 to 1,000 million years old.
The section below crosses 16 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 7×. 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. Age: Mesoproterozoic, 1.2 to 1.6 billion years old. About 7 mi of the line.
Paragneiss. Age: Mesoproterozoic, 1.3 to 1.4 billion years old. About 4 mi of the line.
Biotite-gneiss. Age: Mesoproterozoic, 1.4 to 1.6 billion years old. About 3 mi of the line.
Phyllite, limestone. Age: Silurian to Early Devonian, 394 to 425 million years old. About 1 mi of the line.
Paragneiss, migmatite. Age: Mesoproterozoic, 1.3 to 1.3 billion years old. About 1 mi of the line.
Paragneiss. Age: Mesoproterozoic, 1.2 to 1.2 billion 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. 10 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 Andover reaches Long Island Sound and the Atlantic Ocean by way of Andover Branch, the Williams and the Connecticut: about 200 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Andover; river miles along the main stem, rounded.
Andover has a warm-summer humid continental climate. Summer afternoons average 75° in July; winter nights fall to about 8° in January. About 51 inches of rain fall in a normal year.
Normals 1991–2020 and records since 1940 at Peru, 11 miles west, 540 ft higher. NOAA, through RCC-ACIS.
