Yellowstone

The world's first national park — on top of a supervolcano

Yellowstone is the world's first national park (1872). It sits on top of a giant sleeping volcano! That's why boiling water shoots out of the ground — geysers. The 'Old Faithful' geyser shoots water 40 metres high every 90 minutes. Colourful hot springs look like rainbows — tiny bacteria paint them. Bison, wolves and bears roam free here.

Yellowstone National Park (8,991 km², Wyoming) was founded in 1872 — the first in the world. It sits in the caldera of a supervolcano that erupted 640,000 years ago; beneath it lies a magma chamber 60 km wide. Half the world's geysers (more than 500) are here: Old Faithful (every 60–110 minutes, 30–55 m) and Steamboat, the tallest (90 m). The Grand Prismatic Spring (110 m) is coloured by heat-loving bacteria (thermophiles); their enzyme (Taq polymerase) made PCR tests possible. The return of wolves in 1995 triggered a trophic cascade. The 1988 fire burned 36% of the park, and the forest recovered naturally. It has 4.5 million visitors a year. The chance of the next 'super-eruption' is 1 in 730,000 per year.

Fun facts

• Under Yellowstone lies a 'lake' of magma 60 km wide.
• Half of all the world's geysers are in Yellowstone.
• PCR tests were made possible by an enzyme from a bacterium found in Yellowstone's hot springs!