Monster asteroid?

Here is a story about a massive asteroid striking the Earth 3 billion years ago and perhaps causing the continents to slide.

The effects on the planet were reportedly spectacular. The impact would have set off a planet-wide firestorm, evaporating the surface of the Earth's oceans and causing earthquakes over 10.8 on the Richter scale that lasted over half an hour, and triggered more seismic activity across the globe.

The impact would have wiped out many of the species in existence at the time, allowing others to take over – much as the loss of the dinosaurs helped mammals grow to become one of the dominant species on the planet. It could also be responsible for shifting the planet's tectonic plate system into a higher gear.

thanks to Instapundit for linking to the story.