Transcript Geologic History and the Evolution of Life

Geologic History and the
Evolution of Life
Geologic Time
The beginning and/or
end of each unit of
geologic time reflects
an important event in
the geologic or
biologic history of
Earth
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.
CAMBRIAN PERIOD
542-488 mya
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)
ORDOVICIAN PERIOD
488-444 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.
Landforms became predominant
amongst the oceans. Sophisticated life
forms continues to evolve as oxygen
levels continued to rise including
multicellular organisms.
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.
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.
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.
Evolution of Life
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.
The evolution of life can be seen as
sequences of evolutionary events
represented in the fossil 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?
RT = Pg. 3
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.
Why are fossils from the past found in New York
very different from the organisms that live there
today?
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).