The Pearsall 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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Pearsall’s center stands about 620 ft above sea level. Within three miles the land runs from 570 ft to 680 ft, a difference of 110 ft: gently rolling country.
The section below crosses 8 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.
Siltstone, sandstone. Age: Middle Eocene, 38 to 48 million years old. About 11 mi of the line.
Sandstone. Age: Middle Eocene, 38 to 48 million years old. About 4 mi of the line.
Gravel. Age: Late Pliocene to Pleistocene, less than 3.6 million years old. About 3 mi of the line.
Fine-detrital, coarse-detrital. Age: Holocene, less than 12,000 years old. About 2 mi of the line.
Claystone, sandstone. Age: Eocene, 34 to 56 million years old. About 2 mi of the line.
Coarse-detrital, fine-detrital. Age: Pleistocene, less than 2.6 million years old. 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. 2 smaller units 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 Pearsall reaches Corpus Christi Bay and the Gulf of America by way of Buck Creek, the Frio and the Nueces: about 220 river miles.
Lakes on the way: Horseshoe Tank and Lake Corpus Christi.
75 miles of the trip are on the Frio.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Pearsall; river miles along the main stem, rounded.
