The Erin 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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72° on Nov. 11, 2022, the hottest reading for this week of the year since 1893. Next is 69° in 1964.
Erin’s center stands about 1,060 ft above sea level. Within three miles the land runs from 940 ft to 1,250 ft, a difference of 310 ft: rolling country. The highest named summit within 15 miles is Holy Hill, about 1,350 ft, 1 miles east.
Under the town center the state geologic map shows Silurian, undivided (dolostone), from the Silurian, 422 to 445 million years old.
The section below crosses 3 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 43×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Dolostone. Age: Silurian, 422 to 445 million years old. About 14 mi of the line.
Shale, dolostone. Age: Ordovician, 445 to 487 million years old. About 7 mi of the line.
Dolostone. Age: Ordovician, 445 to 487 million years old. About 3 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 Erin reaches the Gulf of America by way of the Little Oconomowoc, the Oconomowoc, the Rock River and the Mississippi: about 1,740 river miles.
Lake on the way: Lake Koshkonong.
1,450 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Erin; river miles along the main stem, rounded.
Erin has a warm-summer humid continental climate. Summer afternoons average 80° in July; winter nights fall to about 9° in January. A normal year brings about 36 inches of snow; with the rain, that comes to about 34 inches of water.
On November 14 Erin normally reaches 44° and falls to 26°. The record high is 69°, in 1999; the record low 5°, in 1995. The most rain on this date, 0.87 in, fell in 1991.
Normals 1991–2020 and records since 1893 at Hartford Wwtp, 7 miles north-northwest. NOAA, through RCC-ACIS.
