The St. Johnsville 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. Johnsville’s center stands about 500 ft above sea level. Within three miles the land runs from 300 ft to 1,100 ft, a difference of 800 ft: hilly country. The highest named summit within 15 miles is Mount Independence, about 2,240 ft, 15 miles south.
Under the town center the state geologic map shows Beekmantown Group (dolostone), from the Cambrian to Early Ordovician, 471 to 497 million years old.
The section below crosses 11 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 12×. 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: Middle Ordovician, 459 to 471 million years old. About 5 mi of the line.
Dolostone. Age: Cambrian, 487 to 542 million years old. About 4 mi of the line.
Charnockite, gneiss. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 3 mi of the line.
Siltstone, shale. Age: Late Ordovician, 445 to 459 million years old. About 3 mi of the line.
Hornblende-gneiss. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 2 mi of the line.
Dolostone. Age: Cambrian to Early Ordovician, 471 to 497 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. 5 smaller units 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. Johnsville reaches New York Harbor and the Atlantic Ocean by way of Zimmerman Creek, the Mohawk and the Hudson: about 230 river miles.
160 miles of the trip are on the Hudson.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of St. Johnsville; river miles along the main stem, rounded.
