In 1971 heavy rain fell across much of East Nebraska. In the summer paleontologist Mike Voorhies travelled to the farmland around the Midwest town of Orchard. What he was to discover exceeded his wildest dreams. It was a sight of sudden prehistoric disaster. Voorhies' digging revealed the bones of 200 fossilized rhinos together with the prehistoric skeletons of camels, lizards, horses and turtles. Dating shows they all died abruptly 10 million years ago. The cause of death, however, remained a mystery. It was not from old age...

Hidden deep beneath the Earth's surface lie one of the most destructive and yet least-understood natural phenomena in the world - supervolcanoes. Only a handful exist in the world but when one erupts it will be unlike any volcano we have ever witnessed. The explosion will be heard around the world. The sky will darken, black rain will fall, and the Earth will be plunged into the equivalent of a nuclear winter.

Normal volcanoes are formed by a column of magma - molten rock - rising from deep within the Earth, erupting on the surface, and hardening in layers down the sides. This forms the familiar cone shaped mountain we associate with volcanoes. Supervolcanoes, however, begin life when magma rises from the mantle to create a boiling reservoir in the Earth's crust. This chamber increases to an enormous size, building up colossal pressure until it finally erupts.