Which U.S. National Park contains more than half of the world's geysers?

• A. Grand Canyon National Park
• B. Yosemite National Park
• C. Zion National Park
• D. Yellowstone National Park

Answer: (D)

Geysers occur when groundwater is heated by hot rocks nearby and the pressure builds until an eruption releases the steam and water. The crucial idea is that a large, active geothermal system with many heat sources and pathways for water to circulate can produce many geysers in one area. Yellowstone National Park sits atop a massive, long-lasting volcanic system with a shallow magma chamber, which heats and pressurizes groundwater over a vast region. That setup creates far more geysers than anywhere else on Earth, so the park contains more than half of the world’s geysers. The other parks are renowned for different features—Grand Canyon for its massive canyon, Yosemite for granite cliffs and waterfalls, and Zion for canyons and rock formations—but they don’t have the same intense geothermal activity and density of geysers as Yellowstone.