A View of Earth`s Past

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Transcript A View of Earth`s Past

A view of Earth’s Past
Objectives:
 Summarize how evolution is related to geologic
change.
 Interpret a geologic time scale.
Arizona State Standard:
Strand 6: Concept 3:
P04: Interpret a geologic time scale
P06: Investigate theories of how life originated on Earth.
P07: Describe how life on Earth has influenced the
evolution of Earth’s system.
P08: Sequence major events in Earth’s evolution.
Geologic Time
PO 8: Sequence major events in the
Earth’s evolution using relative and
absolute data (e.g., mass extinctions,
ice ages).
PO 4: Interpret a geologic time scale
The geologic Column
A time line of
Earth’s history
Ordered rock
layers based on
relative age
Distinguishable by
type of rock and
fossils.
 Think back, what
is relative age?
Relative age is the
age of an object in
relation to the ages
of other objects
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Why did many
scientist have to
work together to
develop the
geologic column?
Explain why
constructing
geologic columns
is useful to Earth
scientist.
Scientist worked together because different
rocks occur in different parts of the world.
A geologic column is useful because it
shows the relative ages of rocks and fossils
How can scientist use the
geologic column to determine
the absolute age of earth’s
major events?
 Ice ages
 Mass extinctions
 Organisms explosions
o Ice cores
trap gasses
that tell about
past climates
and changes
in the
environment.
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o Radiometric
dating can be
used to
determine the
absolute age
of fossils and
the
surrounding
rock
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Divisions of Geologic Time
Marked by major changes in Earth’s
surface, climate, and type of organisms.
Divided into smaller units characterized
by type of fossil.
Units of Geologic Time
 Eons: Largest Unit of geologic time.
 Most are in Pre-Cambrian time.
 Eras: Divided into smaller Units.
 Paleozoic
 Mesozoic
 Cenozoic
 Periods: Eras are divided into smaller units of time
characterized by fossil type.
 There are 11 periods.
 Epochs: Divided into smaller units called ages
Precambrian time & The Paleozoic Era.
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Precambrian Time
 Began with the formation of Earth
 Makes up 88% of Earth’s History
 Difficult to interpret due to
deformation caused by tectonic
activity.
 Fossils are rare
 No hard parts to preserve.
 Stromatolites formed by blue green
algae.
 Form in warm, shallow waters.
The Paleozoic Era
 Includes:
 Cambrian Period:
 First Vertebrates
 Ordovician Period:
 Oxygen rich atmosphere
 Silurian Period:
 First Land Plants
 Devonian Period:
 First amphibians appear
 Carboniferous Period:
 First Reptiles
 Permian:
 Pangea is complete
 Mass Extinction from environmental
changes.
The Mesozoic Era: Age Of Reptiles
 Triassic Period:
 Pangea begins to break
apart, and first mammals
begin to appear.
 Jurassic Period:
 First primitive birds.
 Cretaceous Period:
 First Flowering Plants
 The last dinosaurs
become extinct.
 Meteorite Impact: Impact
hypothesis.
The Cenozoic Era:
Age of Mammals
Tertiary Period: Modern Mammals
Quaternary Period: First Hominids
The Cenozoic Era:
Age of Mammals
Tertiary Period: Modern Mammals
Whales
Carnivores
Hoofed Animals
Primates
First grasses appear
India collides with Asia.
Antarctica drifts over the south pole.
 Quaternary Period: First Hominids
Modern ice age begins
Modern Humans appear
Evolution
P06: Investigate theories of how life
originated on Earth.
PO7:Describe how life on Earth has
influenced the evolution
of Earth’s systems
The gradual development of new
organisms from preexisting organisms.
Evolution occurs from natural selection
Models of evolution include:
 High Temperature
 Low Oxygen
 Clay Catalyst
High Temperature
Earth’s surface temperature was extremely
hot and the atmosphere was noxious.
 The air contained CH, NH, and H
 Outgassing from the molten rock produced
an enormous amount of water vapor.
 Eventually forming a cloud layer that covered
the entire planet.
 Violent storms fueled with lightening sparking
followed
Earth’s ancient atmosphere, combined
with the intense electrical storms, was
essential for the production of the
molecules that cells need to survive.
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Low Oxygen
 First unicellular life appears in the
Precambrian time when oxygen was not
present in the atmosphere.
 Organisms that thrived in this
atmosphere were anaerobic--does not
require free oxygen.
Clay Catalyst
 Clay served as a storage for amino
acids to join together.
 Water is absorbed between platelets in
clay.
 Clay dries with proteins inside, then
when moist again the proteins will
return.
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How has life on Earth
influenced the evolution of
Earth’s systems?
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