The Arley 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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Arley’s center stands about 740 ft above sea level. Within three miles the land runs from 500 ft to 800 ft, a difference of 300 ft: rolling country. The highest named summit within 15 miles is Hickory Knob, about 960 ft, 14 miles north.
Under the town center the state geologic map shows Pottsville Formation (upper part) (shale, siltstone, sandstone), from the Carboniferous, 299 to 324 million years old.
The section below crosses 2 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 42×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Sandstone. Age: Carboniferous, 299 to 324 million years old. About 15 mi of the line.
Shale, siltstone, sandstone. Age: Carboniferous, 299 to 324 million years old. About 9 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 Arley reaches Mobile Bay and the Gulf of America by way of Dismal Creek, the Sipsey Fork, the Mulberry Fork, the Black Warrior, the Tombigbee and the Mobile: about 460 river miles.
Lake on the way: Lewis Smith Lake.
170 miles of the trip are on the Tombigbee.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Arley; river miles along the main stem, rounded.
