Card Set Information
Ordered arrangement of rock layers.
Eons divided into smaller units of geological time.
Eras are divided into shorter time units.
Divide a period into shorter time units.
Is the gradual development of new organisms from preexisting organisms.
Known as the formation of earth and ended about 542 million years ago
ended about 251 million years ago.
enormous amount of species died.
ended about 65 million years ago.
division of geologic time