Download Bio 1309 Early Earth History 4 Billion Years old! Horrible Place!

Bio 1309
Early Earth History
Slide 1
4 Billion Years old!
First the earth – really inhospitable!
Then the moon !
The great bombardment!
Slide 2
Horrible Place!
• No free Oxygen
• High Radiation (no ozone yet…) (so what is
ozone anyway?)
• Noxious gasses with sulfur, carbon monoxides,
dangerous chemicals
• LOTS of volcanic activity
• Water likely not buffered .. (whats a buffer?)
Slide 3
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So What changed?
• Earliest bacteria – Archae made Oxygen.
• Earth rusted
(iron III oxides)
Slide 4
Grand Canyon example
Slide 5
Impact Craters!
The Barringer Crater in Arizona - .74 miles across, 560 ft deep
http://www.haydenplanetarium.org/tyson/read/2009/06/05/musings-of-a-solo-ist-astrophysicist-the-humanist
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Riding the Continents - Pangaea
• Pangaea was a
supercontinent that
formed about 300
million years ago
– It began to break apart
around 200 million years
ago
Slide 7
Riding the Continents – Pangaea
Separates
• Pangaea broke into two
continents:
– Laurasia
• Laurasia was the more
northerly of the two
continents
– Gondwanaland
• Gondwanaland was the
more southerly of the two
Slide 8
Riding the Continents – Jurassic
Period
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Riding the Continents –
Cretaceous Period
Slide 10
Riding the Continents - Now
Slide 11
Riding the Continents
Slide 12
4
Riding the Continents - Evidence
• Fossil evidence for
Pangaea includes
presence of similar
and identical species
on continents now
great distances apart
• For example, fossils of
the therapsid,
Lystrosaurus, found in
South Africa, India and
Australia
Slide 13
Therapsid?
Definition:
• any of various groups of mammal-like reptiles of
the extinct order Therapsida
• inhabiting all continents from midPermian to late Triassic times
• Some of which were probably warmblooded and directly ancestral to mammals.
Slide 14
Pangea Examples of Organisms
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Riding the Continents - Range
• Lystrosaurus fossils
have been found
together with members
of the Glossopteris flora
– distribution would have
ranged from polar circle
to equator if the
continents were in their
present position
Slide 16
Lystrosaurus & Glossoptera
Slide 17
Riding the Continents • Similarly, the freshwater
reptile, Mesosaurus,
has been found in only
localized regions of the
coasts of Brazil and
West Africa
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Mesosaurus – Only Africa & Brazil
Slide 19
Riding the Continents – Geo
Evidence
• Additional evidence for
Pangaea found in
geology of adjacent
continents
– Includes matching
geological trends
between eastern coast
of South America and
western coast of Africa
Slide 20
South America and western coast of Africa
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Riding the Continents – More Data
• The polar ice cap of the
Carboniferous Period
covered the southern end
of Pangaea
• Glacial deposits of till, of
the same age and
structure found on many
separate continents that
would have been
together in the continent
of Pangaea
Slide 22
So what is Till?
Till Definition:
mixture of rocks, boulders, and soil picked up by a moving
glacier and carried along the path of the ice advance.
The glacier deposits it along its path: on the sides of the
ice sheet, at the toe of the glacier when it recedes, and
across valley floors when the ice sheet melts.
Till deposits are like the footprint of a glacier and are
used to track the movement of glaciers.
Slide 23
Till Deposits
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Riding the Continents – Magnetic
Data
Paleomagnetic study of
apparent polar wandering
paths support theory of
super-continent
Orientation of magnetic
minerals in rocks show
movement of continental
plates
Slide 25
Paleomagnetism Data
Slide 26
Riding the Continents- Mountains
• The continuity of
mountain chains provides
evidence for Pangaea
• One example Appalachian Mountains
chain extends from
northeastern United
States to the Caledonides
of Ireland, Britain,
Greenland, and
Scandinavia
Slide 27
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Mountain Data
• The Appalachian Mountains chain
extends from northeastern United
States to the Caledonides of Ireland,
Britain, Greenland, and Scandinavia!
Slide 28
Mountain Data
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