Last updated: January 23, 2024
Place
At The Stairs: Foundations for a New Life
NPS/Sean Dupre'
Quick Facts
Location:
Gila Hot Springs
Significance:
Cliff Dwellings
Designation:
National Monument
Amenities
1 listed
Benches/Seating
You are standing on the edge of a caldera, the collapsed remains of a giant volcano! About 28 million years ago, the ground under your feet exploded and shot huge amounts of ash and shards of volcanic glass into the sky. As this material fell to the ground, it was still hot and welded together into a stone called tuff.
Later volcanoes oozed lava over the welded tuff forming the darker andesite rock above. As the lava erupted, escaping gasses left the many holes you see in the hillside today.
Cave Formation in the Gila Conglomerate
As the volcanoes quited, the long process of steady erosion began. Ground level was once at the height of the caves. The creek slowly began to carve laterally through the weak points in the canyon walls. The final result was large caves, scoured out of the Gila Conglomerate. This is where the Mogollon people built their homes over 700 years ago.
Later volcanoes oozed lava over the welded tuff forming the darker andesite rock above. As the lava erupted, escaping gasses left the many holes you see in the hillside today.
Cave Formation in the Gila Conglomerate
As the volcanoes quited, the long process of steady erosion began. Ground level was once at the height of the caves. The creek slowly began to carve laterally through the weak points in the canyon walls. The final result was large caves, scoured out of the Gila Conglomerate. This is where the Mogollon people built their homes over 700 years ago.