The Oldest Rocks on EarthEarth has existed for an immense period of timean almost unimaginable 4. 6 billion years. If we ventured far enough into the past, would we reach a time when our planet was fundamentally different? Did it always have landscapes like those we see today, sculpted by wind, rain, and the forces of plate tectonics? When did Earth turn into the distinctive blue planet where life could emerge and evolve? Geologist Simon Lamb shows that the key to answering