Geography
How Sinkholes Form in Karst and Affect Human Settlements
Quick fact
The largest sinkhole ever discovered is in China—the Xiaozhai Tiankeng, which is more than 600 meters deep, big enough to hold several city blocks.
Why this is interesting
Imagine driving down a quiet street and suddenly the road vanishes into a pit. How does solid ground become a yawning hole? You may be witnessing the hidden power of water dissolving rock beneath your feet.