The Gourley 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.
Gourley’s center stands about 710 ft above sea level. Within three miles the land runs from 660 ft to 830 ft, a difference of 170 ft: gently rolling country.
Under the town center the state geologic map shows Black River Limestone, from the Late Ordovician, 445 to 459 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 49×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Limestone, dolostone. Age: Late Ordovician, 445 to 459 million years old. About 11 mi of the line.
Dolostone. Age: Early Ordovician, 471 to 487 million years old. About 7 mi of the line.
Limestone. Age: Late Ordovician, 445 to 459 million years old. About 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 Gourley reaches Lake Michigan by way of the Cedar River: about 18 river miles. From there it moves on through the Great Lakes, over Niagara Falls and down the St. Lawrence to the Atlantic.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Gourley; river miles along the main stem, rounded.