The Blue 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.
Blue’s center stands about 580 ft above sea level. Within three miles the land runs from 510 ft to 660 ft, a difference of 150 ft: gently rolling country. The highest named summit within 15 miles is Caddo Hills, about 830 ft, 6 miles north-northwest.
Under the town center the state geologic map shows Alluvium (fine-detrital), from the Holocene, less than 12,000 years old.
The section below crosses 5 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 63×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Fine-detrital. Age: Holocene, less than 12,000 years old. About 13 mi of the line.
Claystone. Age: Early Cretaceous, 100 to 145 million years old. About 7 mi of the line.
Sandstone, shale. Age: Late Cretaceous, 66 to 100 million years old. About 2 mi of the line.
Marlstone. Age: Early Cretaceous, 100 to 145 million years old. About 0.9 mi of the line.
Sandstone, shale. Age: Late Cretaceous, 66 to 100 million years old. About 0.6 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 Blue reaches the Gulf of America by way of the Blue River, the Red River, the Atchafalaya and the Lower Atchafalaya: about 790 river miles.
610 miles of the trip are on the Red River.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Blue; river miles along the main stem, rounded.