Card Set Information
an ordered arrangement of rock layers that is based on the relative age of the rocks and in which the oldest rocks are at the bottom.
a unit of geologic time that includes two or more period.
a unit of geologic time that is longer than an epoch but shorter than an era.
a subdivision of geologic time that is longer than an age but shorter than a period.
the process of change by which new species develop from preexisting species over time
the geologic era that followed precambrain time and that lasted from 542 million to 251 million years ago
the interval of time in the geologic time scale from earths fromation to the begining of the paleoic era from 4.6 billion to 542 million years ago.
an episod during which large number of species become extinct
the geologic era that lasted from 251 million to 65.5 million years ago; also called the age of reptiles.
the current geologic era, which began 65.5 million years ago; also called the age of mammals