The Pecan Gap 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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Pecan Gap’s center stands about 580 ft above sea level. Within three miles the land runs from 470 ft to 610 ft, a difference of 140 ft: gently rolling country.
Under the town center the state geologic map shows Wolfe City Formation (sandstone-mudstone), from the Late Cretaceous, 66 to 72 million years old.
The section below crosses 7 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.
Clay. Age: Late Cretaceous, 66 to 72 million years old. About 6 mi of the line.
Claystone. Age: Late Cretaceous, 66 to 72 million years old. About 6 mi of the line.
Fine-detrital, coarse-detrital. Age: Holocene, less than 12,000 years old. About 4 mi of the line.
Chalk. Age: Late Cretaceous, 66 to 100 million years old. About 4 mi of the line.
Sand. Age: Pleistocene to Holocene, less than 2.6 million years old. About 3 mi of the line.
Sandstone-mudstone. Age: Late Cretaceous, 66 to 72 million years old. About 2 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 1 smaller unit 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 Pecan Gap reaches the Gulf of America by way of East Fork Jernigan Creek, Jernigan Creek, the South Sulphur, the Sulphur, the Red River, the Atchafalaya and the Lower Atchafalaya: about 690 river miles.
Lake on the way: Wright Patman Lake.
320 miles of the trip are on the Red River.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Pecan Gap; river miles along the main stem, rounded.
