Geological History of Guadalupe Mountains National Park

The geological history of Guadalupe Mountains National Park is very much the reason why it became a National Park back in 1972. Never mind the natural beauty of the place, the hiking trails and the chance to lose yourself in the wilderness, geologists flock to Guadalupe Mountains National Park from all over the world to study the Permian Reef, formed an astonishing 250 million years ago – no wonder they thought it was worth protecting, this is undeniably one of the finest fossil reef examples in the world.

The Permian Period (when the Permian Reef was formed) was between 280 and 225 million years ago, the surface of the earth was already shifting and evolving, life on earth was changing from primitive forms like fungi and algae to fish, insects and amphibians. Thin plates on the earths crust were moving around steadily changing the pattern and the supercontinent, known as Pangaea was still all in one piece. That’s how long ago we’re talking.

Anyway, some time during the Permian Period a reef began to develop close to the Delaware Sea, this reef is now known as the Capitan Reef and is widely recognized as being one of the very best fossil reefs in the world, and the best exposure of this reef is in the Guadalupe Mountains. The reef stopped growing somewhere towards the end of this period although it had thrived and expanded for millions of years, but changes to the landscape caused changes to the life of the sea. The ocean outlet became restricted and the Delaware Sea began to evaporate, trouble was it was evaporating faster than it was being replenished. Minerals were precipitated from the disappearing waters and drifted along the sea floor to form bands of sediments, and eventually, over the following thousands of years the bands began to fill up the basin entirely and cover the reef.

26 million years ago or so (give or take a decade), there was a fault in the area which uplifted the Capitan Reef from its long burial, almost two miles from the original location. The uplifted block became exposed to the forces of erosion – wind and rain caused the erosion of the softer, overlying sediments exposing the more resistant materials of the reef. These days the reef towers high above the floor of the desert, just like it once covered the Delaware Sea floor an incredible 250 million years ago.