Mammoth Cave, the world's longest known cave system, stretches 426 miles under Kentucky. The cave's limestone began forming 330 million years ago when the region was submerged under an ocean. Visitors ...
International research and highly-specialized divers are bringing an underground, underwater world to the surface ...
On Sunday’s episode of The Excerpt podcast: Hidden beneath Earth’s surface are caverns and pathways that hold the secrets of our planet’s very beginnings. Even after decades of exploration, there are ...
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