The Madison 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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Madison’s center stands about 690 ft above sea level. Within three miles the land runs from 530 ft to 740 ft, a difference of 210 ft: rolling country.
The section below crosses 6 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 47×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Gneiss. Age: Precambrian to Paleozoic. About 8 mi of the line.
Gneiss, amphibolite. Age: Precambrian to Paleozoic. About 6 mi of the line.
Gneiss. Age: Precambrian to Paleozoic. About 5 mi of the line.
Gneiss. Age: Precambrian to Paleozoic. About 3 mi of the line.
Amphibolite, biotite-gneiss, mica-schist. Age: Precambrian to Paleozoic. About 2 mi of the line.
Biotite-gneiss, amphibolite. Age: Precambrian to Paleozoic. About 0.9 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 Madison reaches the Atlantic Ocean by way of Horse Branch, North Sugar Creek, Sugar Creek, the Oconee and the Altamaha: about 320 river miles.
180 miles of the trip are on the Oconee.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Madison; river miles along the main stem, rounded.
