geologic time scale review GREEN

Geologic Time Scale

• Division of _______________________

Geologic Time Scale

• Based on the _____________________ that lived only during certain periods

Divisions of the Geologic Time Scale

• ______________

  • Longest subdivision

Divisions of the Geologic Time Scale

• ______________

  Marked by major, world wide changes in types of fossils present

Divisions of the Geologic Time Scale

• ______________

  Categorized by the types of life existing

Divisions of the Geologic Time Scale

• ______________

  Smaller units of time

Divisions of the Geologic Time Scale

What determines when a time division begins or ends?

Index Fossils 

• Remains of species that existed on Earth for____________

Index Fossils 

What do geologists use to estimate the age of rocks

This picture is an example of

Precambrian Time

4.5 billion years ago - 544 million years ago = 4 billion years of time

Contains ____________ of Earth’s history

Precambrian Time

• Cyanobacteria: Blue-green algae

• Tiny, soft-bodied organisms

  these are examples of ?

Paleozoic Era

544 million years ago - 248 million years ago

What type of life was present?

Paleozoic Era

• First _________________ appear - FISH!

• Life moved on to land

Paleozoic Era

First _____________ extinction happens

Mesozoic Era - “Middle Life”

248 million years ago - 65 million years ago

Age of the dinosaur!

Appearance of _____________, _______________, and _______________

Mesozoic Era - “Middle Life”

2nd Mass __________________ happens

Cenozoic Era - “Recent Life”

• 65 million years ago - Today

• Known as the "age of ______"

Cenozoic Era - “Recent Life”

• Most recent _____________ accured

• The process in which groups of species _________________________________

what percentage of a species needs to gone in order for it to be considered extinct?

what percentage of a species needs to gone in order for it to be considered endangered?