The Speaker 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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Speaker’s center stands about 800 ft above sea level. Within three miles the land runs from 770 ft to 870 ft, a difference of 100 ft: gently rolling country.
The section below crosses 5 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.
Shale. Age: Carboniferous, 324 to 359 million years old. About 12 mi of the line.
Sandstone. Age: Carboniferous, 324 to 359 million years old. About 10 mi of the line.
Sandstone. Age: Late Devonian, 359 to 384 million years old. About 1 mi of the line.
Black-shale. Age: Devonian to Carboniferous, 324 to 422 million years old. About 1 mi of the line.
Shale. Age: Late Devonian, 359 to 384 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 Speaker reaches Lake St. Clair by way of Black Creek, the Black River and the Saint Clair: about 90 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 Speaker; river miles along the main stem, rounded.
