Nature
Santa Elena Canyon
The Rio Grande enters a limestone wall here and comes out the other side 8 miles later having cut a slot up to 1,500 feet deep and in places barely 30 feet wide. The rock is the same Cretaceous limestone that forms the Edwards Plateau, lifted here into the Mesa de Anguila block along a fault; the river was already running its course when the block began to rise, and it cut down as fast as the…
Nature
The Chisos Mountains
The only mountain range entirely contained within a U.S. national park, and the southernmost range in the continental United States. The peaks are volcanic — lava flows, ash falls and intrusions from a period of intense eruption between about 47 and 32 million years ago, sitting on top of much older sedimentary rock.
Nature
The Marathon Basin
The low, sharply folded ridges here are a window into rock that is buried everywhere else in Texas. These are Paleozoic sediments, up to about 500 million years old, crumpled when the ancestral North American and South American plates collided to build the Ouachita mountain chain around 300 million years ago.
Elsewhere in Texas
Hear it from the road
Whistlestop tells you this story automatically when you drive past. No searching, no tapping, nothing to ask.
