The Londonderry 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.
Mostly cloudy
Partly cloudy; warmer
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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.
Londonderry’s center stands about 1,180 ft above sea level. Within three miles the land runs from 1,070 ft to 1,850 ft, a difference of 780 ft: hilly country. The highest named summit within 15 miles is Stratton Mountain, about 3,940 ft, 11 miles south-southwest.
Under the town center the state geologic map shows Biotite-quartz-plagioclase gneiss, from the Mesoproterozoic, 1.2 to 1.6 billion years old.
The section below crosses 19 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 8×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Paragneiss, metadacite. Age: Mesoproterozoic, 1.3 to 1.3 billion years old. About 5 mi of the line.
Gneiss. Age: Mesoproterozoic, 1.2 to 1.6 billion years old. About 3 mi of the line.
Granofels, quartzite. Age: Cambrian to Early Ordovician, 471 to 542 million years old. About 2 mi of the line.
Paragneiss. Age: Mesoproterozoic, 1.3 to 1.4 billion years old. About 2 mi of the line.
Quartz-feldspar-schist, granofels. Age: Early Ordovician to Middle Ordovician, 459 to 487 million years old. About 2 mi of the line.
Schist. Age: Cambrian to Early Ordovician, 471 to 542 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. 13 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 Londonderry reaches Long Island Sound and the Atlantic Ocean by way of the West River and the Connecticut: about 190 river miles.
150 miles of the trip are on the Connecticut.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Londonderry; river miles along the main stem, rounded.
Londonderry 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, 6 miles west-northwest, 520 ft higher. NOAA, through RCC-ACIS.
