History of Earth

The geologic time scale is a record of _______

• The thickness of sedimentary rock layers

• The rate of fossil formation

• The life forms and geologic events in Earth’s history

Longest subdivisions; based on abundance of fossils is called what?

• Eons

• Periods

• Epochs

Divided periods characterized by differences in life forms

• Eon

• Epoch

• Era

Based on types of existing life globally at a particular time is called what?

• Eon

• Period

• Epoch

Marked by significant worldwide changes in the types of fossils present in rock

• Eon

• Epoch

• Era

The Paleozoic, Mesozoic, and Cenozoic are divisions in the geologic time scale called _____

• Eon

• Epoch

• Era

1. On the geologic time scale, the _________ Era is divided into the Triassic, Jurassic, and Cretaceous periods.

• 1. Mesozoic

• Cenozoic

• Paleozoic

1. The present day is part of the ____________________ Era.

• 1. Mesozoic

• Cenozoic

• Paleozoic

1. Geologic time begins with the longest span of time called __________________ Time.

• Precrotoun

• 1. Precambrian

• Hammer

1. The earliest life forms were _____.

• Dinosaurs

• Single-Celled Organisms

• Mammoths