Geologic Time Scale (pg 6)

Geologic Time Scale (pg 6)

• A timeline of Earth’s history

Geologic Time Scale (pg 6)

• A timeline of Earth’s history• Based on both relative dating and absolute

dating

Geologic Time Scale (pg 6)

• A timeline of Earth’s history• Based on both relative dating and absolute

dating• Divides time into eons, eras, and periods

Creating the Geologic Time Scale

• The divisions are based on changes in the fossil record in different layers of rock

Creating the Geologic Time Scale

• The divisions are based on changes in the fossil record in different layers of rock

• Scientists use radiometric dating to determine the age of each rock layer

Eras1. Precambrian: Covers almost 90% of Earth’s

history. Single-celled organisms

Eras1. Precambrian: Covers almost 90% of Earth’s

history. Single-celled organisms2. Paleozoic: Animals and plants appear. This

era begins with the “Cambrian explosion” with many strange new types of animals

Eras1. Precambrian: Covers almost 90% of Earth’s

history. Single-celled organisms2. Paleozoic: Animals and plants appear. This

era begins with the “Cambrian explosion” with many strange new types of animals

3. Mesozoic: Dinosaurs, mammals, and flowering plants appear

Eras1. Precambrian: Covers almost 90% of Earth’s

history. Single-celled organisms2. Paleozoic: Animals and plants appear. This

era begins with the “Cambrian explosion” with many strange new types of animals

3. Mesozoic: Dinosaurs, mammals, and flowering plants appear

4. Cenozoic: Mammals become dominant