History of the Earth
Too much time
on my hands.
Let’s go to the
fossil record.
That’s some
radioactive decay
you have on.
Take up your
super
positions.
Correlate the
correlation.
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Final Jeopardy
What are the necessary conditions for a
once living organism to turn into a
fossil?
• Organisms need to be buried quickly to avoid decay
• Organisms usually need hard parts that can be imprinted
into the rock layers
Is the Principle of Superposition more related to
relative dating or absolute dating? Why?
Relative Dating. The principle tells us
position of the rock layers compared to
other layers. It does not tell us their
absolute age.
< 120 mya
120 mya
> 120 mya
What is the principle of
horizontality?
The force of gravity does the work to lay down
sediments in flat layers. Eventually, the flat
layers of sediment may turn into sedimentary
rock. This is similar to how we see the horizon.
Traces, imprints, or the remains of onceliving things are called…
Fossils
Explain uniformitarianism
• Uniformitarianism states that Earth slow
processes that happen today are similar
to those that occured in the past
Organize these layers in the events in which they
occurred. (Oldest to Youngest)
A
B
C
Bonus $100
D
The principle that
cut these layers?
D-C-B-A
The Principle of
Crosscutting
What are the three ingredients that
make a good index fossil?
Although
Bonus
they200:
had both
1.Hard parts
Why
hardwere
partseurypterids
and were
2.Lived abundantly
widespread
not good
onand
theindex
Earth.
fossils?
They on
lived
during
many
widespread
the
Earth
time.
3.Lived for aperiods
short of
period
of time
Bonus
Question
Compare and Contrast
a trace fossil with a regular fossil
Both are the remains, imprints,
or traces of once-living
organisms preserved in rocks
Only trace fossils provide
tracks and other evidence of
animal activity
Why do we study fossils?
Answer questions like:
When did life begin?
What did ancient
organisms look like?
How did they live?
Don’t they
Also help you
date rock
layers?!
What is the principle of lateral
continuity?
Rock layers will continue sideways in all
directions
If layers are missing in the middle, we can
assume that they were once connected.
What is the principle of inclusions?
As younger rocks form, pieces older rocks are
included in them.
xenoliths
What is the half-life
of an isotope?
Bonus
The half life refers to the time it
takes for radioactive material,
the isotope, to “ half ” or 50%
decay.
Material usually
has many
Bonus
200:“half
Every 5,730
years
before
lives” before
itiscompletely
½
of Carbon-14
What
the half material
life of
decays.
decays.
Carbon-14
What is the Principle of
Superposition?
In layers of undisturbed rock the youngest rock
are on top and the oldest rocks are on the
bottom.
Younger
Older
Normally, the three particles of the
atom work to _________
balance the
overall charge and _____________
stabilize
of the atom.
Occasionally, scientists find the original
remains of creatures. What substance or
conditions have been known to preserve
organisms?
• Amber
• Tar
• Ice
Don’t even
think about
touching
my DNA!
What are the building blocks of
all matter whether its living or
non-living?
The mighty little
ATOM
Geologists estimate the Earth to
be approximately how many
millions of years old?
4,600 million
Or
4.6 billion
What is the principle of faunal
succession?
Fossils can be used to correlate and date
rock layers
If you were studying the age of rock layers and
did not have access to absolute dating methods,
how could you get an approximate age of the
rock layers?
• Relative dating methods, like
using the principle of
superposition and other
principles.
When rock layers are spread over a
large area, we match them up.
What’s that called?
Correlating
rock layers
What is usually unstable
parent material or daughter product?
Parent material
When unstable atoms break
down, what’s the process called?
Radioactive decay
What is an unconformity in the
rock layers?
• When rock layers do
-Bonus
not follow
the300normal
When younger
layers of rock
relative
age
order,
form horizontally on top of the
according
to
the
6
eroded and tilted layers.
principles.
They can’t
Getting an accurate relative
be relatively
correlated.
age is a problem.
-Bonus 300What is a angular
unconformity?
Absolute dating is a process that uses
the properties of ______
atoms in rocks and
other materials, like petrified
remains, to determine their ages.
What is the difference between a mold and
a cast?
• A mold of a species is
created when rock forms
around the body and then
the body decays.
• If sediment fills the mold
and hardens a cast of the
species is formed.
Final Jeopardy
Compare and Contrast:
Relative Dating
And Absolute Dating
Final Jeopardy Answer
Absolute and relative dating are both used to
calculate and understand the geologic and evolutionary
history of the Earth. Relative dating uses rules like the
Principle of Superposition, older layers on the bottom;
newer layers on top, to arrive at a relative, not exact,
age of Earth. By understanding unconformities,
geologist can correlate rock layers to match when and
where geologic events took place. Absolute dating is
more of an exact science. It uses the radioactive decay
of isotopes to calculate the age of a fossil and rock
layer. Each isotopes has a half-life that scientist use to
measure the age. Both absolute and relative dating
work together to help scientists understand the history
of the Earth.
Jeopardy does not contain all the information you
need to know for the test. Continue to review your
notes, class work, and/or the online PowerPoints
Our next area of
study will be…
PLATE
TECTONICS!!
(Yes, that includes
volcanoes.)
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