The Brackettville 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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Brackettville’s center stands about 1,110 ft above sea level. Within three miles the land runs from 1,080 ft to 1,270 ft, a difference of 190 ft: gently rolling country. The highest named summit within 15 miles is Turkey Mountain, about 1,790 ft, 14 miles east-northeast.
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 34×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Gravel. Age: Late Pliocene to Pleistocene, less than 3.6 million years old. About 11 mi of the line.
Limestone. Age: Early Cretaceous, 100 to 145 million years old. About 5 mi of the line.
Black-shale, siltstone. Age: Late Cretaceous, 66 to 100 million years old. About 5 mi of the line.
Marlstone, chalk. Age: Late Cretaceous, 66 to 100 million years old. About 1.0 mi of the line.
Limestone. Age: Late Cretaceous, 66 to 100 million years old. About 0.8 mi of the line.
Marl. Age: Late Cretaceous, 66 to 100 million years old. About 0.8 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 Brackettville reaches the Gulf of America by way of Las Moras Creek and the Rio Grande: about 560 river miles.
Lake on the way: Paz Ramirez Lake.
270 miles of the trip are on the Rio Grande.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Brackettville; river miles along the main stem, rounded.
