Geologic History and the Evolution of Life. Geologic Time Fossil evidence found in rocks allow...
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Transcript of Geologic History and the Evolution of Life. Geologic Time Fossil evidence found in rocks allow...
Geologic History and the Evolution of Life
Geologic Time Fossil evidence found in rocks allow scientists to determine the age of rocks.
Ages of geologic time can be broken down into eons, eras, periods and epochs.
The beginning and/or end of each unit of
geologic time reflects an important event in
the geologic or biologic history of
Earth
For example: The Cambrian Period began 542 mya –a
point in Earth’s history where a large number of primitive, soft-bodied animals evolved.
The Cambrian Period ended 488 mya when specific invertebrate organisms
(brachipods) became the dominant form of animal life. (beginning of the Ordovician
Period)
CAMBRIAN PERIOD542-488 mya
ORDOVICIAN PERIOD488-444 mya
The Evolution of Planet Earth
It is estimated that the origin of the Earth can be dated back
some 4.6 X 109 years.
During this period of time Earth was still very hot and largely molten due to impact events, the
decay of radioactive molten material, and gravitational forces within the Earth.
During this molten phase, Earth interior zones became established as denser material settled to the
Earth’s core.
Hundreds of millions of years after its creation, the Earth cooled enough to develop a
crust.
As the crust cooled, it is inferred that gases trapped within other zones of the
Earth began to seep into the atmosphere.
This outgassing event lasted millions of years and released nitrogen, water vapor
and carbon dioxide.
As the Earth continued to cool, water in the atmosphere precipitated to Earth
and oceans formed. Primitive life forms (bacteria) began to evolve in these
oceans using carbon dioxide as a fuel source and releasing oxygen as a waste
product.
Nearly 2 billion years later, oxygen levels in the atmosphere continued to rise,
oceans increased in size and the development of sedimentary rocks was
taking place.
Landforms became predominant amongst the oceans. Sophisticated life forms continues to evolve as oxygen
levels continued to rise including multicellular organisms.
Evolution of LifeThe evolution of life can be seen as sequences of
evolutionary events represented in the fossil record.
Organic evolution is the process of change over time. Organisms that
have favorable, genetic variations that allow
them to adapt to environmental changes
will survive.
These organisms that survive will reproduce
and pass these favorable genetic variations to
their offspring.
At times, the evolutionary change of
groups of organisms can be recorded in the
rock record.
Horses have
evolved over the past 55 million years.
Fossils of horses have
shown a change in size, tooth shape and leg design.
Geologic History of New York
Why does New York State not have an entire geologic record of Earth’s history?
Due to the theory of plate tectonics, it can be inferred
that New York’s position on the Earth now is not what is was
in the past.
As the North American plate shifted over time. New York state was thrust into higher
and lower latitudes from where it is today.
Changes in latitude impacted the climate of New York. Different organisms and
different environments are associated with different
climates.
This would explain why there are gaps in the rock record in
New York. This would also explain why organisms found in New York today are different from those of the past (fossils).
Why are fossils from the past found in New York very different from the organisms that live there today?
RT = Pg. 3