Download L15 Early Earth and Atmosphere

What is
this?
Earth,
4 billion
years ago!
The Changing Earth and Atmosphere
What is different about this Early Earth?
Video: Formation of Earth
• We are going back to 4.6 billion years ago.
• Watch the video and answer the questions.
• Imagine what it would be like to be on the
early Earth.
Formation of the Earth
1. How long ago was the Earth formed?
4.6 billion years ago
2. How did the Earth first form?
Rocks collided from gravitational force with such
force that they melted and stuck together
3. Describe the conditions of early Earth.
Extremely hot, covered in lava, violently volcanic
Formation of the Atmosphere
Atmosphere = the envelope of gases surrounding
the earth or another planet.
4. How did the first atmosphere form?
Volcanic eruptions released gases
5. What gases were in the first atmosphere?
Mostly water vapour and carbon dioxide
(methane, hydrogen, and ammonia present
also) similar to Mars and Venus
6. What vital (to us) gas is missing?
Oxygen
Changing Earth
7. What happened when the Earth cooled and
the atmosphere became saturated?
Water vapour condensed into liquid water
(rain) and formed the oceans
8. Describe the conditions of the Earth at this
point.
Cooled to form thin crust, first oceans
9. Give a brief description of continental drift
and plate tectonics.
Atmosphere Today
What is the composition of the modern atmosphere?
Gas
Nitrogen
Oxygen
Argon
Carbon Dioxide
Other
Percentage
78%
21%
0.9%
0.04%
Trace
Early Atmosphere
(estimate)
Other
Gases
Carbon 10%
Dioxide
10%
Modern Atmosphere
Where
does this
come
from?
Carbon Other
Argon Dioxide
0.09% 0.03% Gases
(Trace)
Oxygen
21%
Water
Vapour
80%
Nitrogen
78%
Changing Atmosphere
Photosynthesis Produces Oxygen
• The first photosynthetic organisms were able
to use the energy from the sun to break down
water molecules for energy.
Carbon Dioxide + Water  Glucose + Oxygen
• The oxygen first built up in the oceans, then
finally the atmosphere.
Theories About Life
• Primordial soup theory
states that chemicals in
the atmosphere and
oceans reacted in the
presence of sunlight or
lightning to make
complex molecules that
are the basis for life.
Miller-Urey Experiment
• (1953) Tested if early
atmosphere and
lightning could form
complex molecules
needed for life
• Many amino acids
(basis for proteins)
formed in the
experiment
• Supports the primordial
soup theory