The Alton 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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73° on Nov. 11, 2020, the hottest reading for this week of the year since 1926. Next is 70° in 2022.
Alton’s center stands about 550 ft above sea level. Within three miles the land runs from 500 ft to 1,370 ft, a difference of 870 ft: hilly country. The highest named summit within 15 miles is Belknap Mountain, about 2,380 ft, 9 miles west-northwest.
Under the town center the state geologic map shows Lower part of Rangeley Formation (metaclastic), from the Silurian, 434 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 13×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Pelitic-schist, metasandstone. Age: Silurian, 434 to 445 million years old. About 7 mi of the line.
Quartzite, metasedimentary. Age: Silurian, 422 to 445 million years old. About 5 mi of the line.
Monzodiorite. Age: Jurassic, 145 to 202 million years old. About 5 mi of the line.
Metaclastic. Age: Silurian, 434 to 445 million years old. About 4 mi of the line.
Granite. Age: Late Devonian, 359 to 384 million years old. About 1 mi of the line.
Granite. 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 Alton reaches the Atlantic Ocean by way of Lake Winnipesaukee, the Winnipesaukee and the Merrimack: about 160 river miles.
Lake on the way: Lake Winnipesaukee.
120 miles of the trip are on the Merrimack.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Alton; river miles along the main stem, rounded.
Alton has a warm-summer humid continental climate. Summer afternoons average 82° in July; winter nights fall to about 12° in January. A normal year brings about 62 inches of snow; with the rain, that comes to about 46 inches of water.
On November 14 Alton normally reaches 48° and falls to 30°. The record high is 62°, in 2010; the record low 8°, in 2019. The most rain on this date, 3.40 in, fell in 1937.
Normals 1991–2020 and records since 1926 at Lakeport 2, 14 miles west-northwest. NOAA, through RCC-ACIS.
