The Marathon 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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Marathon’s center stands about 4,050 ft above sea level. Within three miles the land runs from 3,960 ft to 4,260 ft, a difference of 300 ft: rolling country. The highest named summit within 15 miles is Old Blue Mountain, about 6,230 ft, 15 miles north-northwest.
Under the town center the state geologic map shows Woods Hollow Shale, Fort Pena Formation, Alsate Shale, Marathon Limestone, and Dagger Flat Sandstone, undivided, from the Cambrian to Middle Ordovician, 459 to 497 million years old.
The section below crosses 8 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 8×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Limestone. Age: Cambrian to Middle Ordovician, 459 to 497 million years old. About 6 mi of the line.
Coarse-detrital. Age: Pleistocene, less than 2.6 million years old. About 5 mi of the line.
Coarse-detrital. Age: Pleistocene to Holocene, less than 2.6 million years old. About 5 mi of the line.
Sandstone-mudstone, sandstone, black-shale. Age: Carboniferous, 299 to 359 million years old. About 3 mi of the line.
Limestone, dolostone. Age: Permian, 252 to 299 million years old. About 2 mi of the line.
Shale. Age: Permian, 252 to 299 million 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. 2 smaller units 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 Marathon reaches the Gulf of America by way of Peña Colorado Creek, Maravillas Creek and the Rio Grande: about 850 river miles.
Lakes on the way: Paz Ramirez Lake and Amistad Reservoir.
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 Marathon; river miles along the main stem, rounded.
