Earth

1
Earths History

• 4 Eras of Geologic Time

2
4 Eras of Geologic Time

• Precambrian
• Paleozoic
• Mesozoic
• Cenozoic

3
(No Transcript)
4
Precambrian Events

• The earths crust formed
• The atmosphere formed
• The oceans formed
• First life forms developed

5
The earths crust

• The earth was very hot from its formation (The
  nebular theory)
• It cooled from the outside
• As it cooled, the earths crust formed and
  cracked to form plates

6
An atmosphere developed

• Volcanic activity was very common as the crust
  formed and cracked
• CO2 and Nitrogen
• H20 vapor
• Methane, ammonia, and sulfur dioxides

7
Earths atmosphere

• Earth has an atmosphere for 3 reasons
• Volcanic history
• Mass of the planet
• Amount of radiation from the sun

8
The oceans formed

• As the earth continued to cool, the water vapor
  in the atmosphere condensed and fell as rain.
• This water formed the oceans, rivers, lakes,
  streams, and underground water ways.

9
What were the conditions on the early earth?

• Intense volcanic activity
• Warm, shallow seas
• Turbulent atmosphere
• Lots of lightning
• Lots of storms

10
How did life form on this planet?

• Life originated on this planet
• Life was seeded here by
• A comet carrying carbon compounds
• An asteroid carrying single-celled life forms

11
What did the first organisms on earth look like?

• The oldest fossils of life on this planet are
• Bacteria
• Blue Green algae

12
Bacteria

• Single-celled life forms
• No true nucleus or organelles (prokaryotes)
• Very hardy and resistant to extreme conditions
• Many species do not need oxygen

13
Blue Green Algae

• Single celled organisms
• Prokaryotes
• Able to photosynthesizeuse CO2 and H2O to
  produce glucose (food) and O2
• Put tons of oxygen into atmosphere

14
Oxygen in the atmosphere

• Toxic to many forms of bacteria
• Changed our atmospheric makeup by adding ozone to
  the earths atmospheric makeup
• O2 is converted to O3 (ozone) by lightning

15
What happens to early life forms?

• In order to survive they must adapt to using
  oxygen
• Single-celled organisms that have well-defined
  nuclei develop (eukaryotes)
• Multicellular algal forms develop (first plants)

16
PaleozoicAge of Fishes

• Paleomeans early and zoic means animals
• Life exploded on the planet
• Many marine life forms developed
• Plants and animals move onto land
• Small wetlands plants and simple insects
• Amphibians developed
• Atlantic ocean begins to develop and continents
  begin to move apart

17
MesozoicAge of Reptiles

• Meso means middle -zoic means animals
• All continents joined together at the beginning
  of this era, but begins to break apart
• Animalsdinosaurs evolve and become extinct
• Plantsferns the predominant plant formflowering
  plants evolve

18
(No Transcript)
19
(No Transcript)
20
CenozoicAge of Mammals

• Ceno means recent -zoic means animals
• Mammals evolve and flourish
• Humans and human civilizations develop