The Acton 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 sunny
Mostly sunny
Mostly sunny
Partly cloudy
Mostly cloudy
Partly cloudy
Showers likely
74° on Nov. 14, 1990, the hottest reading for this week of the year since 1887. Next is 69° in 1953.
Acton’s center stands about 1,170 ft above sea level. Within three miles the land runs from 1,160 ft to 1,240 ft, a difference of 80 ft: gently rolling country.
Under the town center the state geologic map shows Little Falls Formation (schist, slate), from the Paleoproterozoic, 1.6 to 2.5 billion years old.
The section below crosses 5 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 64×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Schist, slate. Age: Paleoproterozoic, 1.6 to 2.5 billion years old. About 9 mi of the line.
Age: Paleoproterozoic, 1.6 to 1.8 billion years old. About 8 mi of the line.
Sandstone, siltstone, shale. Age: Middle Cambrian to Cambrian, 487 to 521 million years old. About 7 mi of the line.
Gabbro, mafic-hypabyssal. Age: Paleoproterozoic to Mesoproterozoic, 1 to 2.5 billion years old. About 1 mi of the line.
Orthogneiss, migmatite. Age: Paleoarchean to Mesoarchean, 2.8 to 3.6 billion years old. About 0.1 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale.
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 Acton reaches the Gulf of America by way of Grove Creek, the North Fork Crow, the Crow and the Mississippi: about 2,000 river miles.
Lake on the way: Lake Pepin.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Acton; river miles along the main stem, rounded.
Acton has a warm-summer humid continental climate. Summer afternoons average 81° in July; winter nights fall to about 0° in January. About 30 inches of rain fall in a normal year.
On November 14 Acton normally reaches 40° and falls to 22°. The record high is 74°, in 1990; the record low −6°, in 1940. The most rain on this date, 0.70 in, fell in 1951.
Normals 1991–2020 and records since 1887 at Litchfield, 7 miles east-northeast. NOAA, through RCC-ACIS.
