... the planet, sending up a gigantic plume of gas and debris and blasting outwards a rapidlyexpanding shock wave. As fragment after fragment hammered intothe planet, spectacular images were gathered ... waves, earthquakes, tsunamis, and wildfires. Many urban centres in Europe, Africa, and Asia appear tohave collapsed almost simultaneously around 2350 bc, and recordsabound of flood, fire, quake, ... northern Canada, and Australia, and some craters are sobig that their true form can only be seen from space. Today,satellites have helped in the identification of over 172 impact cratersall over...