The Martha 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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Martha’s center stands about 1,410 ft above sea level. Within three miles the land runs from 1,380 ft to 1,450 ft, a difference of 70 ft: gently rolling country. The highest named summit within 15 miles is King Mountain, about 2,380 ft, 11 miles north-northeast.
Under the town center the state geologic map shows Terrace Deposits (coarse-detrital, fine-detrital), from the Pleistocene, less than 2.6 million years old.
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 23×. 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: Pleistocene, less than 2.6 million years old. About 9 mi of the line.
Shale. Age: Permian, 252 to 299 million years old. About 5 mi of the line.
Gypsum, dolostone. Age: Permian, 252 to 299 million years old. About 4 mi of the line.
Fine-detrital. Age: Holocene, less than 12,000 years old. About 3 mi of the line.
Shale, siltstone. Age: Permian, 252 to 299 million years old. About 2 mi of the line.
Granite. Age: Middle Cambrian, 497 to 521 million 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.
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 Martha reaches the Gulf of America by way of Bitter Creek, the Salt Fork Red, the Red River, the Atchafalaya and the Lower Atchafalaya: about 1,150 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Martha; river miles along the main stem, rounded.
