Geologic Time Notes Page 3 Geologic Time
Geologic Time Notes Page 3 Geologic Time Fossils can only be found in rocks. sedimentary.
Dec 22, 2015
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Geologic Time
Notes Page 3
Geologic Time
Notes Page 3
Geologic TimeGeologic Time
Fossils can only be found in
rocks.
Fossils can only be found in
rocks.
sedimentarysedimentary
Why is this statement false: “The caveman had
dinosaur for breakfast.”?
Why is this statement false: “The caveman had
dinosaur for breakfast.”? man and
dinosaursnever lived at the same time
man and dinosaurs
never lived at the same time
Relative AgeRelative Age
If a sedimentary rock outcrop has not been overturned, which layer would be the oldest? What is this principle known as?
If a sedimentary rock outcrop has not been overturned, which layer would be the oldest? What is this principle known as?
Principle of SuperpositionPrinciple of
Superposition
oldest rock layers are on bottom
oldest rock layers are on bottom
Using this principle, label the strata below from oldest to youngest.
Using this principle, label the strata below from oldest to youngest.
Faults are always (older, younger)
than the rocks they cut through.
Faults are always (older, younger)
than the rocks they cut through.
Which is older:
F or S
How do you know?
If a geologist finds an igneous sill, how can she determine if the sill is an
intrusion or an extrusion?
If a geologist finds an igneous sill, how can she determine if the sill is an
intrusion or an extrusion?
IntrusionsIntrusions
contact metamorphism on all sidescontact metamorphism on all sides
extrusionsextrusions
no contact metamorphism on topno contact metamorphism on top
Is “H” an intrusion or extrusion?
How can you tell?
Is “H” an intrusion or extrusion?
How can you tell?
H is an intrusion.Contact
metamorphism on top
H is an intrusion.Contact
metamorphism on top
What is an unconformity? What is an unconformity?
a buried erosional surface a buried erosional surface
a part of the rock record
is missing
a part of the rock record
is missing
How does it complicate the relative dating of rock layers?
How does it complicate the relative dating of rock layers?
What processes could lead to an unconformity? What processes could lead to an unconformity?
weathering and erosion weathering and erosion
Using the diagram to the left, identify where the unconformity is located by drawing an arrow and writing the word “unconformity” next to it.
What characteristics must fossils have in order to be
good index fossils?
What characteristics must fossils have in order to be
good index fossils?
lived over a large geographic area (large horizontal distribution)
lived for a short period of time (small vertical distribution)
lived over a large geographic area (large horizontal distribution)
lived for a short period of time (small vertical distribution)
In the diagram below, a geologist has matched up
rock layers based on index fossils. In the diagram below, a geologist has matched up
rock layers based on index fossils. In geology, this is referred
to as CORRELATION In geology, this is referred
to as CORRELATION
EvolutionEvolutionExplain the theory of evolution. Explain the theory of evolution.
organisms adapt to their environment
in order to survive
organisms adapt to their environment
in order to survive
EvolutionEvolutionExplain how the fossil record supports this theoryExplain how the fossil record supports this theory
can see that different organisms have
changed over time
can see that different organisms have
changed over time
Why are radioactive isotopes useful in determining the absolute age of a rock?
their half-lives are constanttheir half-lives are constant
What can be done to change the half-life of a radioactive isotope?
Why is this important?
NOTHING!it is reliable to calculate age
What radioactive isotope could be used to determine the absolute
age of material that was recently living?
carbon-14
What radioactive isotope could be used to determine the absolute
age of material that was recently living?
carbon-14
What is the half life of uranium-238?
4.5 x 109
4,500,000,000
4.5 billion years
choice (c)
If there is a 100g sample of C14, how many grams of C14 would remain after three half-lives?
How long would this take? Show all work.
100g 50g 25g 12.5g
3 half-lives x (5.7 x 103) =1.71 x 104 = 17,100 years
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