The Iosco 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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Iosco’s center stands about 930 ft above sea level. Within three miles the land runs from 890 ft to 1,000 ft, a difference of 110 ft: gently rolling country. The highest named summit within 15 miles is Sugarloaf Hill, about 1,130 ft, 15 miles south.
The section below crosses 6 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 6 mi of the line.
Sandstone. Age: Carboniferous, 324 to 359 million years old. About 6 mi of the line.
Shale. Age: Carboniferous, 324 to 359 million years old. About 4 mi of the line.
Limestone. Age: Carboniferous, 324 to 359 million years old. About 3 mi of the line.
Shale. Age: Carboniferous, 324 to 359 million years old. About 3 mi of the line.
Sandstone. Age: Late Devonian, 359 to 384 million years old. About 2 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 Iosco reaches Lake Michigan by way of the West Branch Red Cedar, the Red Cedar and the Grand River: about 200 river miles. From there it moves on through the Great Lakes, over Niagara Falls and down the St. Lawrence to the Atlantic.
150 miles of the trip are on the Grand River.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Iosco; river miles along the main stem, rounded.
