Walter Alvarez and his team made one of the most astonishing scientific discoveries of the twentieth century - that an asteroid smashed into the Earth 65 million years ago, exterminating the dinosaurs. Alvarez had the first glimmer of that amazing insight when he noticed something odd in a rock outcrop in central Italy. In this major new work Alvarez now returns to that rich terrain, this time to take the reader on an excavation of the Earth's distant past. We encounter the volcanoes that formed the Seven Hills of Rome; the majestic limestone Appennine mountains that started to develop millions of years ago under water; the evidence that the Mediterranean Sea completely evaporated to a sunken desert, perhaps several times; and the proof that continental plates once overran one another to form the Alps. In Alvarez's telling, all major geologic episodes are as dramatic as the great impact that killed the dinosaurs.