Devil’s Sinkhole Formation: How Water Created a Real Bat Cave

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Tony Maples Photography


Though most know the Devil’s Sinkhole for its massive bat flights, it also is a geological feature that bears study. You will likely find the story of its formation as fascinating as watching the millions of bats that call the sinkhole home when they leave on a fall evening. One of the most interesting aspects of the Devil’s Sinkhole formation is how common these holes occur in Texas. In fact, the same phenomenon that created this feature continues to occur today, even in major cities.

Devil’s Sinkhole Formation

Devil's Sinkhole Formation

Photo: Facebook/Devil’s Sinkhole State Natural Area – Texas Parks and Wildlife

While some geologic features form in moments from earthquakes or volcanoes, others can take millions of years, such as mountains. The Devil’s Sinkhole formation falls in between these extremes. Geologically speaking, this sinkhole formed in the blink of an eye, but it still took thousands of years. Almost a million years ago, water fell from the sky and sank into the ground, where it picked up minerals, slightly acidifying it. This acidic water ate away at the delicate limestone of the Edwards Plateau. Over time, it created a vast hole in the rock. As the water table dropped, the water that had once held up the ceiling of the cavern drained away, leaving the roof to cave in, creating the opening of what we know as the Devil’s Sinkhole.

When to Visit

The Devil's Sinkhole Formation Started with Water

Photo: Facebook/Devil’s Sinkhole State Natural Area – Texas Parks and Wildlife

If you want to visit to learn more about the bats and the Devil’s Sinkhole formation for yourself, you cannot just go at any time. Though the Texas Parks and Wildlife Department oversees it, the Devil’s Sinkhole Society runs this natural area. To tour Devil’s Sinkhole, you will need to book a tour with them. While on a guided tour, you will not be permitted to enter the sinkhole, but you can look down into it from the viewing platform above it. Plan your trip to coincide with one of the bat flights for an unforgettable experience.

Sinkholes in the Texas Hill Country

Hurricane Harvey Opened a Sinkhole on a Road Near Houston

Photo: Facebook/Pop Stop

Though the Devil’s Sinkhole formation took several thousand years, sinkholes still occur today in much less time. The most frequent cause of sinkholes in Texas today is large amounts of rain. Occasionally, these rains will wash away the dirt under roadways, causing the road itself to collapse. Sadly, Bexar County lost one of its sheriff’s deputies whose car was swallowed by one of these rain-caused sinkholes. Rarer are natural sinkholes that lead to underground caverns. Though these sinkholes do occur and get larger, they are not nearly as common as rain-caused roadway collapses.