The Topsham 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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71° on Nov. 11, 2020, the hottest reading for this week of the year since 1993. Next is 70° in 2022.
Topsham’s center stands about 90 ft above sea level. Within three miles the land runs from 0 ft to 220 ft, a difference of 220 ft: rolling country. The highest named summit within 15 miles is Oak Hill, about 720 ft, 14 miles north-northwest.
Under the town center the state geologic map shows Ordovician - Precambrian Z Cushing Formation (felsic-volcanic, mafic-volcanic), from the Neoproterozoic to Ordovician, 445 to 1,000 million years old.
The section below crosses 4 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 48×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Felsic-volcanic, mafic-volcanic. Age: Neoproterozoic to Ordovician, 445 to 1,000 million years old. About 13 mi of the line.
Slate. Age: Neoproterozoic to Ordovician, 445 to 1,000 million years old. About 5 mi of the line.
Sandstone. Age: Late Ordovician to Silurian, 428 to 459 million years old. About 3 mi of the line.
Mudstone, sandstone. Age: Neoproterozoic to Ordovician, 445 to 1,000 million years old. About 0.6 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 Topsham reaches the Atlantic Ocean by way of the Androscoggin and the Kennebec: about 30 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Topsham; river miles along the main stem, rounded.
Topsham has a warm-summer humid continental climate. Summer afternoons average 79° in July; winter nights fall to about 7° in January. A normal year brings about 78 inches of snow; with the rain, that comes to about 50 inches of water.
On November 14 Topsham normally reaches 46° and falls to 27°. The record high is 64°, in 2010; the record low 6°, in 2019. The most rain on this date, 1.02 in, fell in 2018.
Normals 1991–2020 and records since 1993 at Durham, 9 miles west-northwest. NOAA, through RCC-ACIS.
