Download History of Earth

History
of Earth
By: Mr. Kauffman
Outline
• Early History of Earth
• Structure of Earth
• Changing Structure of Earth
• Plate Tectonics
• Evidence of Early Life
• How Old is Something
• Fossil Record
• History of Life on Earth
Early History of Earth
• How old is the
Earth?
– 4.6 billion years old
(4,600,000,000)
• How do scientists
explain how the
Earth formed?
– Big Bang Theory
– Large explosion 1015 billion years ago
– Created the
universe
Expanding Universe
Early History of Earth
• What was Earth like at first?
– Very hot; constant volcanic eruptions and
meteorite impacts
– Atmosphere consisting of Ammonia, Methane,
Water Vapor, Carbon Dioxide, and Nitrogen
– What was missing?
•Oxygen
Structure of Earth
• The Earth consists
of 4 layers
1. Crust
2. Mantle
3. Outer core
4. Inner core
– The crust and
mantle are called
the lithosphere
Structure of Earth
Structure of Earth
Crust
Mantle
Outer core
Inner core
Changing Structure of Earth
• Continental drift: idea that says the Earth’s
continents are slowly moving across the Earth’s
surface
– Pangea – supercontinent that existed 200 to 300
million years ago
Changing Structure of Earth
• Plate tectonics: scientific theory that explains
the features and movement of the Earth’s
surface in the present and past
– The Earth’s crust is divided into several sections
called tectonic plates
Changing Structure of Earth
Changing Structure of Earth
– These plates are constantly gliding/moving over
the top of the mantle
– The movement of the plates is driven by thermal
(heat) energy of the Earth
Plate Tectonics
• There are 3 types of tectonic plate boundaries
(places where the tectonic plates meet)
1. Divergent – occurs when the plates move away
from each other
• The space created between the plates is
filled by magma which solidifies into rock
Plate Tectonics
• There are 3 types of tectonic plate boundaries
(places where the tectonic plates meet)
2. Convergent – occurs when the plates collide
together
• Forms mountains over long periods of time
Plate Tectonics
• There are 3 types of tectonic plate boundaries
(places where the tectonic plates meet)
3. Transform – occurs when the plates slide past each
other
• Causes earthquakes
Evidence of Early Life
• Fossil: remains or
imprints of long dead
organisms preserved in
the Earth’s surface
– 2 basic types of fossils
1. Imprint: footprints or
plant impressions
2. Remains: bones or teeth
Evidence of Early Life
How Old is Something
• How do scientists determine the
age of a fossil?
– Relative Dating: examine how deep
the fossil is buried
• the deeper it is buried, the older it is
– Radiometric Dating: study radioactive
elements found in the fossil and rocks
around it
Fossil Record
• Collection of all types of fossilized organisms that
have been discovered
• Millions of species of fossilized organisms have
been discovered
– Estimated to be about 2% of all species that have lived
on Earth
– New species are still being found
• 2 patterns can be observed
– Fossils appear in order
• Not random, not mixed together
• Example – don’t find human remains with dinosaur remains
– As we progress through time, fossils look more and more
like modern day creatures
Fossil Record
Fossil Record
Fossil Record
Fossil Record
Fossil Record
History of Life on Earth
• Time frames are divided into periods
– Jurassic is one example
– Each period has certain characteristics specific to it
• What it looks like
• What lives there
• Factors that determine what life could be found
on Earth
– Amount of oxygen
– Continental shift
– Meteors
– Volcanoes
– Climate
Meteorite Craters
¾ of a mile in diameter
111 miles in diameter