The Clark 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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Clark’s center stands about 870 ft above sea level. Within three miles the land runs from 800 ft to 870 ft, a difference of 70 ft: gently rolling country.
Under the town center the state geologic map shows Marmaton Group (limestone, shale), from the Carboniferous, 299 to 324 million years old.
The section below crosses 4 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.
Limestone, shale. Age: Carboniferous, 299 to 324 million years old. About 11 mi of the line.
Shale, sandstone, siltstone. Age: Carboniferous, 299 to 324 million years old. About 5 mi of the line.
Limestone. Age: Carboniferous, 324 to 359 million years old. About 5 mi of the line.
Sandstone. Age: Carboniferous, 299 to 324 million years old. About 4 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 Clark reaches the Gulf of America by way of Big Creek, the Reese Fork, Allen Creek, the Elk Fork Salt, the Salt River and the Mississippi: about 1,390 river miles.
Lake on the way: Mark Twain Lake.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Clark; river miles along the main stem, rounded.
