Sinkholes can be scary to think about. They don’t happen too often, but when they do, they can take people by surprise. The solid ground disappears, and a hole suddenly appears.
It might seem like sinkholes appear out of nowhere. But they actually need specific conditions to form.
To have a sinkhole, you first must have a cave.
“You can think of a sinkhole as the end of the life cycle of a cave,” Kurtis Wilkie, senior instructor of Geology at Washington State University, explained. He is very interested in how Earth’s features form over long periods of time.
Wilkie said caves often occur in rock called limestone. Limestone is made mostly of calcium carbonate (the same substance that makes up seashells!).
“We’re talking not just thousands of years, maybe millions of years. It’s not as if you start the process now and then 10 years or 100 years from now you have a cave. It takes a very long time,” Wilkie said.
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