The Georgetown 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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Georgetown’s center stands about 240 ft above sea level. Within three miles the land runs from 190 ft to 370 ft, a difference of 180 ft: gently rolling country.
Under the town center the state geologic map shows Catahoula formation (sand), from the Miocene, 5.3 to 23 million years old.
The section below crosses 3 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 60×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Sand. Age: Miocene, 5.3 to 23 million years old. About 19 mi of the line.
Sand, gravel. Age: Pliocene to Pleistocene, less than 5.3 million years old. About 4 mi of the line.
Clay, sand. Age: Miocene, 5.3 to 23 million years old. About 1 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 Georgetown reaches the Gulf of America by way of the Pearl: about 240 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Georgetown; river miles along the main stem, rounded.
