Scientists at Yellowstone National Park have uncovered a large, underground magma cap that is likely crucial to containing one of Earth's largest volcanic systems. Hidden 2.4 miles (3.8km) beneath Yellowstone's northeast caldera, the cap acts as a lid for the intense heat and pressure below it, which could otherwise cause large-scale eruptions.

For decades, scientists knew magma was simmering beneath the earth at Yellowstone National Park. A team of researchers recently found out how deep.