San Carlos Formation, Geological formation in Big Bend National Park, Texas, United States
San Carlos Formation is a geological layer found throughout Big Bend National Park, made up of sedimentary rocks stacked in distinct bands that reveal different ages and environments. Walking through the park, visitors can see these rock layers exposed in canyon walls and hillsides, each one telling a story of ancient conditions.
This formation took shape roughly 85 million years ago during the Late Cretaceous, when an ancient seaway covered the Texas region. After the water retreated, the sediments it left behind hardened into the rock layers visitors see today.
Geologists and researchers visit this formation regularly to study the rock layers and collect samples for analysis of Earth's geological history.
You can see this formation best by hiking along the main trails, especially those that run through canyons and along ridge lines in the park. Bring plenty of water and wear sturdy shoes, as the terrain is rocky and the desert sun can be intense.
The rocks here hold fossils and mineral traces of the ancient seaway that once covered this land, providing direct evidence of a warm tropical ocean. These remains make it possible to read the story of an entire ecosystem that flourished millions of years ago in what is now a desert.
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