The Johnstown 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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Johnstown’s center stands about 690 ft above sea level. Within three miles the land runs from 550 ft to 970 ft, a difference of 420 ft: hilly country. The highest named summit within 15 miles is Shaker Mountain, about 2,540 ft, 14 miles north-northwest.
Under the town center the state geologic map shows Canajoharie Shale (black-shale), from the Middle Ordovician, 459 to 471 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 10×. 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 14 mi of the line.
Biotite-gneiss. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 4 mi of the line.
Graywacke, sandstone, siltstone. Age: Late Ordovician, 445 to 459 million years old. About 3 mi of the line.
Charnockite, gneiss. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 1 mi of the line.
Quartzite, schist. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 1 mi of the line.
Gneiss. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 0.8 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 Johnstown reaches New York Harbor and the Atlantic Ocean by way of Mathew Creek, Cayadutta Creek, the Mohawk and the Hudson: about 220 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 Johnstown; river miles along the main stem, rounded.
