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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77° on Nov. 11, 2022, the hottest reading for this week of the year since 1896. Next is 74° in 1911.
Corunna’s center stands about 740 ft above sea level. Within three miles the land runs from 730 ft to 850 ft, a difference of 120 ft: gently rolling country.
Under the town center the state geologic map shows Saginaw Formation (sandstone, shale), from the Carboniferous, 299 to 324 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 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.
Sandstone, shale. Age: Carboniferous, 299 to 324 million years old. About 23 mi of the line.
Shale. Age: Carboniferous, 324 to 359 million years old. About 0.7 mi of the line.
Sandstone. Age: Carboniferous, 324 to 359 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 Corunna reaches Lake Huron by way of the Shiawassee and the Saginaw: about 75 river miles. From there it moves on through the Great Lakes, over Niagara Falls and down the St. Lawrence to the Atlantic.
50 miles of the trip are on the Shiawassee.
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 82° in July; winter nights fall to about 16° in January. A normal year brings about 38 inches of snow; with the rain, that comes to about 34 inches of water.
On November 14 Corunna normally reaches 48° and falls to 31°. The record high is 69°, in 1909; the record low 9°, in 1986. The most rain on this date, 0.95 in, fell in 1931.
Normals 1991–2020 and records since 1896 at Owosso Wwtp, 4 miles northwest. NOAA, through RCC-ACIS.
