The Todd Mission 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.
Todd Mission’s center stands about 310 ft above sea level. Within three miles the land runs from 260 ft to 410 ft, a difference of 150 ft: gently rolling country.
Under the town center the state geologic map shows Willis Formation (coarse-detrital, fine-detrital), from the Pliocene, 2.6 to 5.3 million years old.
The section below crosses 4 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.
Coarse-detrital, fine-detrital. Age: Pliocene, 2.6 to 5.3 million years old. About 16 mi of the line.
Clay, sandstone. Age: Miocene, 5.3 to 23 million years old. About 4 mi of the line.
Silt, sand, clay. Age: Pleistocene, less than 2.6 million years old. About 2 mi of the line.
Fine-detrital, coarse-detrital. Age: Holocene, less than 12,000 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.
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 Todd Mission reaches Galveston Bay and the Gulf of America by way of Mill Creek, Spring Creek, the San Jacinto and Buffalo Bayou: about 100 river miles.
Lake on the way: Lake Houston.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Todd Mission; river miles along the main stem, rounded.