Relative Age Dating of Rocks Put these people in order from youngest to oldest A B C D Relative age Dating of Rocks Can you tell the exact ages of these people Dating Relative age dating ID: 486263
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Slide1
Relative Vs. Absolute Dating of RocksSlide2
Relative Age Dating of Rocks
Put these people in order from youngest to oldest.
A
B
C
DSlide3
Relative age Dating of Rocks
Can you tell the exact ages of these people?Slide4
Dating
Relative age dating-
places the ages of rocks and the events that formed them in order, but without dates.
by comparing one
rock layer
to anotherno
specific date!Slide5
Principle of Uniformitarianism
Uniformitarianism
- the processes happening today are the same ones that happened
millions of years ago
This is why we can
compare
rock layers!Slide6
Relative age Dating of Rocks
Principle of Superposition –
in an undisturbed rock sequence, the
older
rocks are at the bottom and each successive layer is
older than the layer
above it.Slide7
Inclusions
Inclusions-
are pieces of one rock unit that are
within another rock unit
.
Example) Pieces of granite embedded in shale.The rock containing the inclusions has to be
older than the rock that gave the inclusion.Slide8
Intrusions
Intrusions are pieces of one rock unit that
cross cut other layers.
Law of cross- cutting relationship:
If P
“intruded
” rock layers Q, O and N, P
must be younger than Q, O and NSlide9
Principle of
InclusionsSlide10
Inclusions and IntrusionsSlide11
Step 1
: Deposition – horizontalSlide12
Fig. 08.03
Step 1 (cont.)
: Deposition – horizontalSlide13
Fig. 08.04
Step 2
: Intrusion of graniteSlide14Slide15
Fig. 08.05
Step 3
:
Tilting of layers
Step 4
: Erosion to create unconformitySlide16
Fig. 08.06
Step 5a
: Submergence and deposition
of new layersSlide17
Fig. 08.07
Step 5b
: ….. possibly additional formationsSlide18
Fig. 08.08
Step 6
: Intrusion
Through weakness of layersSlide19
Step 7
: Erosion of
Layers-- UnconformitySlide20
Fig. 08.11
Step
8
:
Erosion due to streamSlide21Slide22
Folding
Crustal activity can cause the crust to look
wavy
.Slide23
Folding
Did F form after/before D folded?
A
B
C
D
E
F
GSlide24
Unconformity
An unconformity is something that is
out of the ordinary
in rock layer formation. Unconformity at line XY
The bottom layers were
tilted
by crustal movement.
X
YSlide25
Relative Age Dating
Excercise
Intrusion!
Inclusion!
If layer L is 65 million years old, and layer H is 35 million years old, what is a possible age of intrusion P? What is the possible age of J?
Unconformity!Slide26
Absolute age dating of rocks
Determine the
actual age
(in millions of years) of a rock, fossil or other object.
Use the decay rate of
radioactive isotopes within rocks and fossils.
Radioactive materials emit particles at a constant
rate.Slide27
Absolute Age DatingSlide28
Absolute Age Dating of Rocks
Radiometric dating
-
depending on what elements are present in the fossils we can tell exactly
how old the fossil is. Slide29
Half Life
Half Life-
The time it takes for one element to lose half of its particles.Slide30
Compare and ContrastSlide31
Index Fossils
Remains
of a
plant
or an
animal that can be used by geologists to correlate rock layers
over a large area.Can also be used to date a particular
fossil.CharacteristicsEasily
recognizedAbundantWidely Distributed
Alive for a short period of history