Geologic Time Scale
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Name:
Geologic Change
8.E.2.1 Fossils
 Paleontology
The science involved with the study of a
The data used for this study of a past life are
 Fossils
Fossils are the
that have been preserved by geologic processes.
Provide evidence of how life and the environment has changed
The processes we see today are
to those in the past.
 Uniformitarianism
The idea that the
shaping the earth today has been
at work throughout history.
Erosion
Deposition
Movement of
Changes in
 Catastrophism
The principle that states that all geologic changes
.
Through
such as:
Impact of an
Earthquakes
 6 Types of Fossils
Mold Fossil
Cast Fossil
Petrified (
) Fossil
Preserved Fossil
Carbonized Fossil
Trace Fossil
 Mold Fossil
Forms when sediments bury an organism and the sediments change into rock
The organism decays leaving a
of the organism
 Cast Fossil
Forms when a
that hardens
into the shape of the organism
 Petrified Fossil
Also known as
Forms when
into the buried remains,
replacing the remains, and changing them into rock
 Preserved Fossils
Forms when entire organisms or parts of organisms are prevented from decaying by being trapped in
.
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 Carbonized Fossils
Forms when organisms or parts, like
, are pressed
between layers of soft mud or clay that hardens squeezing almost all the decaying organism away leaving
the
.
 Trace Fossil
Forms when the mud or sand hardens to stone where a
of an organism was left behind
Helps to give clues to an animals
.
Coprolite
 Geologic Time Scale
A record of the major events and the diversity of life forms in Earth’s history
At the end of each era, a
occurred, many kinds of organisms died
out.
 Divisions of Time
Eon:
of time
Containing two or more
Era: a defined period of time with a start event and an end event
Period: form a division which geologist use to divide
.
Epoch: a division of time that is longer than an age, but shorter than a
 Precambrian Era
First era of time
Bacteria and
, leading to jellyfish and sea worms
Few fossils
 Paleozoic Era
Early
, trilobites, leading to early vertebrate fish, arachnids, insects,
first amphibians,
become dominant by the end.
Early land plants, mosses, ferns, cone-bearing plants
 Mesozoic Era
Reptiles were dominant animals,
Small mammals and birds appeared
Flowering plants and types of
increased
Dinosaurs became
at the end of this era
 Cenozoic Era
New mammals appeared
Diversity of life increased
 Relative age of rocks does not tell
 Can be determined using 2 different methods:
Ordering of
Index Fossils
 Ordering of rock layers
The Law of
Each rock layer is older than the one above it.
Younger layers lie on
, unless disturbed.
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 Index Fossils
Used to find the
To be considered an index fossil:
An organism must have lived for a
in Earth’s history
and must be
across the globe.
Trilobites
 Trilobites
Hard shelled animals
3 body sections
Lived in shallow seas
Became extinct about
million years ago.
 Absolute Dating
Absolute dating is any method of measuring the age of an event or object in
.
Radiometric dating
Radioactive “
” decay into “daughter atoms” at a predictable rate.
They become trapped in
when it forms.
By measuring amount left after decay, scientist can predict how much time has passed.
Carbondating is most frequently used.
Half-life: the amount of time needed for
of a radioactive isotope to
disappear.
8.E.2.2 Artifacts of Geologic Change
 Other artifacts scientist can use to determine geological history:
Ice cores
Cylinders of
drilled out of glaciers and polar ice sheets
Help understand how the
over time
Record of
and compounds in the air where it formed.
Examining layers of sedimentary rock
Makes up about
of earths surface
Forms where sand, mud, or other sediments collect
Can be disturbed by
, which is formed from molten rock (
), causing intrusions.
 Geologic Column
An arrangement of rock layers in which the oldest rocks are at the
.
 Disturbed Rocks
Folding: rock layers
Faulting: a
in the earths crust
Intrusion: molten rock that squeezes into existing rock. Always
than the
layer it cuts through.
Tilting: when internal forces in the earth
the layers
 Gaps in the Record
Unconformities: a break in the geologic record created when rock layers are
for a long time
Represent missing time that was not recorded.
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8.L.4.1 Evolution
 Biological evolution: the change over time of
Acquire characteristics through
Change in
that helps an organism survive a
particular environment
Homologous Structures:
(wing of a
bat and arm of a human)
Analogous Structures:
(wing of a bird and
wing of a butterfly)
Fossils can be compared to each other and living organisms to observe any changes over time
Transitional fossils
 Extinction
It occurs when an
and the organism does not have
traits necessary to survive and reproduce.
Most species that have lived on earth are now extinct.
Extinction is apparent in the fossil record.
 Biological Classification
System used to organize all life on Earth.
Used to:
Describe organisms
Examine the relationships between organisms
Also referred to as
(KPCOFGS)
 Theory of Evolution
States that species
Change in response to their environment
Charles Darwin is known as the “
”
Theory that all life is related from a common ancestor
As genetic mutations occur, the beneficial mutations are kept and passed on, because they aid in
survival
The process known as
The beneficial mutation builds and creates an entirely different organism.
 Darwin’s Finches
An example of a
that Darwin researched that adapted their beaks
to eat a type of food source common to the area.
 Factors impacting survival of a species:
Phenotype
Body structure and characteristics
Can influence the ability to find, obtain, or utilize resources (
) and even reproduce
Genotype
The genetic code of an organism
Beneficial vs. Harmful
Physical Conditions
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If the environment changes, the organisms with
to survive
will reproduce and pass on those traits.
Those without the traits most likely die or produce fewer offspring.
The greater the
of a species, the greater the chance for survival during
environmental changes.
 Geological Evolution: change in
.
Theory of
Movement of earth’s
and
plates
 Caused mountains and trenches to form which continually shape the earth’s
surface.
 Movement of the plates causes changes in climate, geographic features, sea
levels, and types of organisms in a location.
Pangaea
 Theory of
Law of Superposition:
In any undisturbed sequence of rocks deposited in layers, the