Summary:
- A hot spring forms where a crack in the Earth allows water to reach the surface after being heated underground.
- Many hot springs are used by people and animals as natural hot tubs.
- Some people believe that hot springs can cure illnesses.
- Only about 1,000 geysers exist worldwide.
- Old Faithful at Yellowstone National Park erupts every 60 to 70 minutes.
- Castle Geyser is another geyser at Yellowstone Park; however, it does not erupt as frequently or predictably as OldFaithful.