chapter 9

a geologic column represents a timeline of earths history.

an era is an eon split into smaller units.

a period is an era split into smaller units.

an epoch is a period split into smaller units.

evolution is the gradual development of new organisms preexisting

The time interval that began with earths formation and ended about 542 million years ago.

The geologic era that began about 542 million years ago and ended about 251 million years ago

The disappearance of Jurassic animals.

Earths surface started to change

The division of earths that began about 65 million years ago