An interstate might seem an arbitrary boundary. But an attentive West Texas traveler driving north of Interstate 10, on Highway 54 from Van Horn to the Guadalupe Mountains, can see they’ve entered a different landscape. Gone are the ruddy volcanic hues of the Davis Mountains country. White dunes and chalky outcrops appear, even as the bright limestone cliffs of Texas’ highest mountains shine on the horizon.
This is the Gypsum Plain, which covers a thousand square miles of West Texas and southern New Mexico. Like the nearby petroleum, this pale, porous gypsum was deposited more than 250 million years ago, in a Permian-age sea. Today, it’s a landscape of sinkholes, sand dunes – and caves.
That includes Parks Ranch Cave, which, with more than 4 miles of mapped passages, is among the world’s longest gypsum caves. It’s a site of discovery for both cavers and geologists.
Ethan Oleson is a University of Arkansas geology PhD student. His research into “speleogenesis” – the forces behind cave formation – took him to caves across the U.S., including Parks Ranch.
“In the United States, it's the only place to go if you want to look at a gypsum cave and understand how gypsum caves form and just play around in a gypsum cave,” Oleson said. “It's this weird, wacky white world of very interesting, almost marble-y looking rock.”
Located on Bureau of Land Management property in New Mexico, a dozen miles from Carlsbad Caverns, Parks Ranch Cave is open to unsupervised exploration. It doesn’t require technical caving skills. But it’s not without its hazards.
The cave has 20 different entrances. Two are readily entered on foot, but most are sinkholes. In March 2025, a solo caver tried to exit one of these vertical openings – and fell 40 feet. He lay for hours with two broken legs, before rescuers found him.
Most caves are formed from the top down, as surface water works its way through limestone, gypsum or dolomite. But Carlsbad Cavern, and other caves near the Guadalupes, formed from the bottom up. Deep beneath the surface, groundwater mingled with petroleum. That produced sulfuric acid, which dissolved rock into wondrous subterranean cavities.
Parks Ranch likely had such an origin. But at some point, it did become a route for surface water. During flash floods, water surged through the cave, filling its passages. And turbulence within those floodwaters produced distinctive cave formations.
Parks Ranch doesn’t have the classic stalagmites and stalactites. Instead, it has features called “scallops” – concave indentations that appear in fields on cave walls.
“Saying ‘scallop’ evokes the sea creature,” Oleson said, “which is kind of accurate. All scallops have this asymmetrical bowl. It looks like somebody went and carved ice cream on the wall with an ice cream scoop successively.”
Scallops have long been a scientific conundrum – mathematical models say they shouldn’t exist. By comparing Park Ranch to caves elsewhere in the world, Oleson gained insight into how scallops form. He found that the type and texture of cave rock play a role, as do the sediments carried by underground floodwaters.
Geologists have long studied the landscapes of the Earth’s surface. But the underground “landscapes” of caves remain mysterious. Parks Ranch, Oleson said, is an ideal place to probe those mysteries.
It’s also a unique Chihuahuan Desert adventure – though the cave should only be explored with proper gear, and companions.
“I encourage everyone to go caving and check out Parks Ranch,” Oleson said. “But do it in a manner that is safe and responsible, with several people. But it's definitely a must see.”
Information on Parks Ranch is available on the BLM’s website, at https://www.blm.gov/visit/parks-ranch-cave.
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