Older Than Dirt
Almost 14 1/2 billion years ago, it all started with a Big Bang, and what began as a cloud of gas, dust, and rock eventually took shape and bloomed into a molten sphere. Battered by asteroid collisions, ice ages, and shifting tectonic plates, our fledgling planet finally pushed forth continents. But if you think Earth has calmed down since then-think again! Geological activity such as earthquakes, volcanoes, and tsunamis continues to sculpt the earth's landscape, sometimes with terrible consequences for its inhabitants.