The St. Mary 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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St. Mary’s center stands about 750 ft above sea level. Within three miles the land runs from 630 ft to 800 ft, a difference of 170 ft: gently rolling country. The highest named summit within 15 miles is Putnam Knob, about 1,240 ft, 12 miles east.
Under the town center the state geologic map shows New Albany, Chattanooga, and Ohio Shales, Boyle Dolomite (Limestone), and Sellersburg Limestone, undivided (black-shale), from the Devonian to Carboniferous, 324 to 422 million years old.
The section below crosses 7 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 28×. 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 to Carboniferous, 324 to 422 million years old. About 8 mi of the line.
Dolostone. Age: Ordovician, 445 to 487 million years old. About 5 mi of the line.
Limestone. Age: Ordovician, 445 to 487 million years old. About 4 mi of the line.
Dolostone. Age: Silurian, 422 to 445 million years old. About 3 mi of the line.
Shale. Age: Devonian to Carboniferous, 324 to 422 million years old. About 2 mi of the line.
Limestone. Age: Ordovician, 445 to 487 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. 1 smaller unit along the line are not listed.
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 St. Mary reaches the Gulf of America by way of Stewarts Creek, the Rolling Fork, the Salt River, the Ohio and the Mississippi: about 1,420 river miles.
970 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of St. Mary; river miles along the main stem, rounded.
