Modern Engineering Marvels on MSN

Deep in Mammoth Cave, shark teeth rebuild a lost tropical sea

The longest mapped network of caves in the world also contains one of the most implausible marine collections in North America. In Mammoth Cave, sharks and their kinsmen are preserved in layers of ...

This National Park Is Home to the Longest Cave in the World—and Only 426 Miles Have Been Explored So Far

Mammoth Cave National Park in Kentucky is home to the world’s longest cave system, with over 426 miles of mapped underground ...