The Thornton 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.
Thornton’s center stands about 490 ft above sea level. Within three miles the land runs from 420 ft to 520 ft, a difference of 100 ft: gently rolling country. The highest named summit within 15 miles is Horn Hill, about 670 ft, 11 miles north-northwest.
Under the town center the state geologic map shows Hooper Formation (claystone), from the Paleocene, 56 to 66 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: Paleocene, 56 to 66 million years old. About 8 mi of the line.
Claystone. Age: Paleocene, 56 to 66 million years old. About 6 mi of the line.
Claystone. Age: Late Paleocene to Early Eocene, 48 to 59 million years old. About 3 mi of the line.
Sand. Age: Paleocene, 56 to 66 million years old. About 3 mi of the line.
Clay, sand. Age: Paleocene, 56 to 66 million years old. About 2 mi of the line.
Fine-detrital, coarse-detrital. Age: Holocene, less than 12,000 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. 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 Thornton reaches the Gulf of America by way of Steele Creek, the Navasota and the Brazos: about 370 river miles.
230 miles of the trip are on the Brazos.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Thornton; river miles along the main stem, rounded.