The Geologic Time Scale and Early Earth Section Review

1
The Geologic Time Scale and Early Earth Section
Review

2
What is the geologic time scale?

• A record of the life forms and geological events
  in Earths history.

3
True or False?

• In order to develop the geologic time scale,
  scientists studied rock layers and fossils
  worldwide and placed Earths rock layers in order
  by relative age. Later, radioactive dating
  helped them determine the absolute ages of the
  divisions.
• TRUE!

4
What are the basic units into which the geologic
time scale is divided?

• Eras and periods

5
What are the 4 Eras introduced in your book?

• Precambrian
• Paleozoic
• Mesozoic
• Cenozoic

6
True or False?

• Scientists hypothesize that Earth formed at a
  different time than the other planets and the sun
  around 2 million years ago.
• FALSE!!!
• The hypothesis states the Earth was formed at the
  same time as the other planets and the sun around
  4.6 billion years ago!

7
What is a comet?

• A ball of dust and ice that orbits the sun.

8
How did volcanic eruptions and comets change
Early Earth?

• They released carbon dioxide and water vapor into
  the atmosphere.

9
What do scientist think were the first organisms
to evolve on Earth?

• Bacteria-like organisms