Transcription: Yellowstone Park in northwest Wyoming is most famous for its 10,000 steam vents, geysers, and mud volcanoes. They are caused by volcanic activity underneath the earth's surface, which heats up water lying underground. This causes a buildup of pressure, which forces liquid or gases through cracks in the earth. The most famous geyser or hot spring in Yellowstone Park is Old Faithful, which erupts about once an hour. you
(.mp4)