Midnight (4.5 billion years ago) — Earth forms from cosmic dust

3:20 A.M. (3.96 billion years ago) — age of oldest rock ever found

9:23 P.M. (500 million years ago) — first animals with backbones

11:00 P.M. (190 million years ago) — age of the dinosaurs

11:35 P.M. (80 million years ago) — Rocky Mountains start to form

11:58 P.M. (6 million years ago) — small stream begins carving Grand Canyon

11:59 P.M. and 26 sec. (1.8 million years ago) — earliest humans appear

11:59 P.M. and 45 sec. (750 thousand years ago) — humans begin using fire

11:59 P.M. and 59 sec. (20 thousand years ago) — last Ice Age