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Geology of Guadalupe Mountains

Between 251 – 299 million years ago, during the Permian period of geologic time, all the continents on Earth were joined together to form the supercontinent of Pangea.

El Capitan, a part of one of the world's most well-preserved fossil reef, Guadalupe Mountains National Park / NPS - D. Buehler

A vast ocean surrounded Pangea and a narrow inlet – the Hovey Channel – connected the ocean with the Permian Basin. There were three arms to this basin: Marfa, Delaware, and Midland basins. Considered to be the world’s most well-preserved fossil reef, the Capitan Reef developed along the edge of the Delaware Basin and thrived there for several million years. The skeletal remains of life in that reef became the sedimentary rock known as Capitan limestone.

Map of the Capitan Reef showing the exposed and buried sections as they are today, Guadalupe Mountains National Park / NPS file

Eighty million years ago, tectonic pressure caused uplift in the region of what is now West Texas and southern New Mexico. Steep fault blocks and erosion created the Guadalupe Mountains and the cliff known as El Capitan that rises 1,000 feet (305 m) above the desert floor.

To learn more about the geology and geologic formations constituting Guadalupe Mountains National Park, click here.

Guadalupe Mountains National Park

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