The Corunna 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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4° on Nov. 13, 2019, the coldest reading for this week of the year since 1989. Next is 12° in 1997.
Corunna’s center stands about 980 ft above sea level. Within three miles the land runs from 900 ft to 1,050 ft, a difference of 150 ft: gently rolling country.
Under the town center the state geologic map shows Antrim Shale (black-shale), from the Devonian, 359 to 422 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 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.
Black-shale. Age: Devonian, 359 to 422 million years old. About 15 mi of the line.
Shale. Age: Carboniferous, 324 to 359 million years old. About 5 mi of the line.
Shale. Age: Devonian to Carboniferous, 324 to 422 million years old. About 4 mi of the line.
Limestone, dolostone. Age: Devonian, 359 to 422 million years old. About 0.5 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 Corunna reaches Lake Erie by way of Cedar Creek, the Saint Joseph and the Maumee: about 180 river miles. From there it moves on through the Great Lakes, over Niagara Falls and down the St. Lawrence to the Atlantic.
140 miles of the trip are on the Maumee.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Corunna; river miles along the main stem, rounded.
Corunna has a warm-summer humid continental climate. Summer afternoons average 81° in July; winter nights fall to about 17° in January. A normal year brings about 36 inches of snow; with the rain, that comes to about 40 inches of water.
On November 14 Corunna normally reaches 48° and falls to 31°. The record high is 64°, in 2009; the record low 13°, in 2018. The most rain on this date, 0.72 in, fell in 2024.
Normals 1991–2020 and records since 1989 at Garrett 1 S, 7 miles south, 110 ft lower. NOAA, through RCC-ACIS.
