his PowerPoint is too large for me to upload so I will take screenshots.
1:08
Relative dating 4U.pdf
☆
ch
Relative dating
• Just like you put the events of your
morning in order, geologists can put
geologic events in the proper order.
6
A big word
• Relative dating, and most of geology, is
based on a basic principle:
• the Principle of Uniformitarianism.
• “The present is the key to the past.”
• It’s the opposite of “catastrophism.”
7
Catastrophism
• The idea that the Earth (and life) has been
shaped by a few sudden, rare events.
• The Biblical flood is an example.
• There is good evidence that some global
catastrophes have occurred.
• Can you think of an example?
8
Principles of Relative
Datino
1
OOO
Dashboard
Calendar
To Do
Notifications
Inbox
1:08
<
Relative dating 4U.pdf
☆
G
1
Relative dating
Geologic time
2
How old is that rock?
Early geologists were not able to measure
the age of rocks and geologic events.
• But they could determine “which came
first."
3
Example
• Put these events in the correct order:
• I arrived at school
• I woke up
• I ate breakfast
• I went to the bathroom
• 1 brushed
my
teeth
4
Answer
• Chances are, this is the correct order:
• I woke up
• I went to the bathroom
• I ate breakfast
• I brushed my teeth
• I arrived at school
1
000
Dashboard
Calendar
To Do
Notifications
Inbox
1:08
Relative dating 4U.pdf
B
ch
Principles of Relative
Dating
9
Basic principles
• In this class, we'll discuss 4 basic principles
of relative dating
• Original horizontality
• Superposition
• Cross-cutting relationships
• Inclusions
10
Original horizontality
11
• Were these layers formed the way they are
now?
• Or did they form in horizontal layers, that
were then tilted later?
12
1
OOO
Dashboard
Calendar
To Do
Notifications
Inbox
1:08
<
Relative dating 4U.pdf
☆
G
12
Original horizontality
• Sediment is deposited in horizontal layers.
• Tilted layers must have been tilted after
they formed.
13
Original horizontality
B
B
Layers were originally
deposited horizontally
Layers were tilted
after their formation
a.
b.
14
When did the tilting occur?
A
E
D
С
B
15
Superposition
1
000
Dashboard
Calendar
To Do
Notifications
Inbox
1:08
Relative dating 4U.pdf
☆
G
16
A
B
• Which layer is the
oldest?
• Which one is the
youngest?
D
17
Superposition
• Each layer is
Deposited last
younger than the
one below it, and
older than the
one above it.
Deposited first
• Or: Layers get
younger as you
go up.
18
In what order were the layers deposited?
A
С
D
B
E
19
Cross-cutting relationships
1
RID
OOO
Dashboard
Calendar
To Do
Notifications
Inbox
1:08
<
Relative dating 4U.pdf
☆
G
1
Relative dating
Geologic time
2
How old is that rock?
Early geologists were not able to measure
the age of rocks and geologic events.
• But they could determine “which came
first."
3
Example
• Put these events in the correct order:
• I arrived at school
• I woke up
• I ate breakfast
• I went to the bathroom
• 1 brushed
my
teeth
4
Answer
• Chances are, this is the correct order:
• I woke up
• I went to the bathroom
• I ate breakfast
• I brushed my teeth
• I arrived at school
1
000
Dashboard
Calendar
To Do
Notifications
Inbox
1:08
Relative dating 4U.pdf
☆
ch
Relative dating
• Just like you put the events of your
morning in order, geologists can put
geologic events in the proper order.
6
A big word
• Relative dating, and most of geology, is
based on a basic principle:
• the Principle of Uniformitarianism.
• “The present is the key to the past.”
• It's the opposite of “catastrophism.”
7
Catastrophism
• The idea that the Earth (and life) has been
shaped by a few sudden, rare events.
• The Biblical flood is an example.
• There is good evidence that some global
catastrophes have occurred.
• Can you think of an example?
8
Principles of Relative
Datino
1
OOO
Dashboard
Calendar
To Do
Notifications
Inbox
1:08
Relative dating 4U.pdf
B
ch
Principles of Relative
Dating
9
Basic principles
• In this class, we'll discuss 4 basic principles
of relative dating
• Original horizontality
• Superposition
• Cross-cutting relationships
• Inclusions
10
Original horizontality
11
• Were these layers formed the way they are
now?
• Or did they form in horizontal layers, that
were then tilted later?
12
1
OOO
Dashboard
Calendar
To Do
Notifications
Inbox
1:08
<
Relative dating 4U.pdf
☆
G
12
Original horizontality
• Sediment is deposited in horizontal layers.
• Tilted layers must have been tilted after
they formed.
13
Original horizontality
B
B
Layers were originally
deposited horizontally
Layers were tilted
after their formation
a.
b.
14
When did the tilting occur?
A
E
D
С
B
15
Superposition
1
000
Dashboard
Calendar
To Do
Notifications
Inbox
1:08
Relative dating 4U.pdf
☆
G
16
A
B
• Which layer is the
oldest?
• Which one is the
youngest?
D
17
Superposition
• Each layer is
Deposited last
younger than the
one below it, and
older than the
one above it.
Deposited first
• Or: Layers get
younger as you
go up.
18
In what order were the layers deposited?
A
С
D
B
E
19
Cross-cutting relationships
1
RID
OOO
Dashboard
Calendar
To Do
Notifications
Inbox
1:08
Relative dating 4U.pdf
☆
20
What formed first?
21
What formed first?
Granite
fault
Amphibolite dike
Granite
fault
22
Cross-cutting relations
• When an intrusion or a fault cuts through
rocks, the rocks being cut are older than
what's doing the cutting.
23
Principle of Inclusions
1
OOO
Dashboard
Calendar
To Do
Notifications
Inbox
1:08
<
Relative dating 4U.pdf
27
Inclusions
Rock B
• Inclusions are pieces of
older rock that are
included in younger rock.
• Inclusions in igneous rock
are called xenoliths.
• Inclusions in sedimentary
rock are called clasts.
Rock A
28
Putting it all together
G
• In your notes,
make a list of the
sequence of
events that
created these
rocks.
F
D
B
• Get your
G
partner to help!
29
Unconformities
30
• So what's going on here?
1
OOO
Dashboard
Calendar
To Do
Notifications
Inbox
1:09
<
Relative dating 4U.pdf
☆
31
Gaps in the record
• An unconformity is a gap in the geologic
record — a missing chapter.
• There are three types of unconformity:
• Disconformity
• Angular unconformity
• Nonconformity
32
Layers form...
Layer D
Layer C
Layer B
Layer A
33
Then the land rises or seas level falls, and
weathering and erosion remove rock.
Layer
Layer A
34
When the land sinks or sea level rises, new
layers form.
Layer H
Layer G
Layer F.
Layer D
Layer A
1
000
Dashboard
Calendar
To Do
Notifications
Inbox
1:09
<
Relative dating 4U.pdf
☆
35
Disconformities
• Unconformities such as on the previous
slide are called disconformities.
• In your notes:
Development of a Disconformity
Deposition of rocks Uplift, & erosion
Subsidence & Deposition
1,2,3, & 4
of rocks 3 & 4
of rocks 6 & 7
-Sea Level
13
6
Disconformity
2
1
36
Angular unconformities
Development of an Angular Unconformity
Deposition of rocks
A,B,&C
Uplift, tilting, & erosion
Subsidence & Deposition
of rocks F&G
-Sea Leve
E
Angular Unconformity
37
Angular?
• Please note that “angular” is an adjective,
and is meaningless without a noun.
• In anatomy, angular is added to the nouns
artery, bone, and vein.
• If the answer is “angular unconformity,” and
you write “angular," it will be wrong!
38
Nonconformities
• If the rocks under the unconformity are
igneous or metamorphic, it's called a
nonconformity.
Development of a Nonconformity
Deposition of rocks
J&K Intrusion or
Metamorphism of
Rock IM
Uplift, & erosion
of rocks J, K,& IM
Subsidence & Deposition
of rocks P&Q
1
000
Dashboard
Calendar
To Do
Notifications
Inbox
1:08
Relative dating 4U.pdf
B
G
Principle of Inclusions
24
Which is older?
Xenolith
Xenolith
(Metamorphic
rock)
Xenolith
Granite
25
Which
is older?
Sedimentary rock
(conglomerate)
Clast of sandstone
My foot
26
Which is older?
Sedimentary rock
(conglomerate)
Clasts of igneous rock
1
000
Dashboard
Calendar
To Do
Notifications
Inbox
1:09
Relative dating 4U.pdf
☆
G
Nonconformities
• If the rocks under the unconformity are
igneous or metamorphic, it's called a
nonconformity.
Development of a Nonconformity
Deposition of rocks Uplift, & erosion Subsidence & Deposition
J&K Intrusion or of rocks J, K,& IM of rocks P &Q
Metamorphism of
Rock IM
-Sea Level
-Q
Nonconformity
IM
39
Questions
• The next few slides will show pictures and
drawings of unconformities.
• Figure out which type each one is!
40
What type of
unconformity is this?
Sedimentary
layers
Inclusions of
igneous rock
Igneous rock
41
What
type
of
unconformity is this?
1
OOO
Dashboard
Calendar
To Do
Notifications
Inbox
1:09
<
Relative dating 4U.pdf
G
45
Whạt type of
unconformity is this?
46
Sedimentary rock
What type of
unconformity
is this?
Granite
47
What
type of
unconformity is this?
48
What type of
unconformity is this?
Granite
Sedimentary rock
1
OOO
Dashboard
Calendar
To Do
Notifications
Inbox
1:09
<
Relative dating 4U.pdf
&
48
What type of
unconformity is this?
Granite
Sedimentary rock
49
What type of
unconformity is this?
Conglomerate
Sandstone with crossbedding
50
Practice
Youngest
51
• 1.
• 2.
• 3.
• Look at the diagram on
the next slide.
• 4.
• 5.
• Place the rock units in
their order of formation,
from oldest to youngest.
• 6.
• 7.
1
000
Dashboard
Calendar
To Do
Notifications
Inbox
1:09
<
Relative dating 4U.pdf
☆
51
Youngest
• 1.
• 2.
• 3.
• Look at the diagram on
the next slide.
• 4.
5.
• Place the rock units in
their order of formation,
from oldest to youngest.
.
6.
• 7.
• 8.
.
9.
• 10.
Oldest
52
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display,
Gneiss
Lava flow
Granite
Limestone
Conglomerate 3 Coal
D
H
.
53
Correlation
54
Correlation
• Using everything we've talked about so far,
you can figure out the relative ages of rocks
in one area.
• But how can you match rocks in one area
with rocks in another area?
• Any thoughts?
• (Hint: reread p. 478–480)
1
OOO
Dashboard
Calendar
To Do
Notifications
Inbox
1:09
G
Relative dating 4U.pdf
What type of
unconformity is this?
47
What type of
42
unconformity is this?
Layer H.
Layer G
Layer F.
LAYED
Layer A
43
What type of
unconformity is this?
44
What type of
unconformity is this?
1
OOO
Dashboard
Calendar
To Do
Notifications
Inbox
1:09
<
Relative dating 4U.pdf
☆
54
Correlation
• Using everything we've talked about so far,
you can figure out the relative ages of rocks
in one area.
• But how can you match rocks in one area
with rocks in another area?
• Any thoughts?
• (Hint: reread p. 478–480)
55
Correlation
• We can match layers by:
• Physical continuity
• Similarity of rock types
• Fossils (fossil succession)
56
Fossil Succession
的
57
Fossil succession
• The principle of fossil succession (often
called faunal succession) states that fossils
are found in a repeatable order.
• This is true because over the age of the
Earth, organisms have evolved, lived for a
time and then sana avtinct
1
000
Dashboard
Calendar
To Do
Notifications
Inbox
1:09
<
Relative dating 4U.pdf
☆
G
57
Fossil succession
• The principle of fossil succession (often
called faunal succession) states that fossils
are found in a repeatable order.
• This is true because over the age of the
Earth, organisms have evolved, lived for a
time, and then gone extinct.
• As one species goes extinct, others evolve.
58
Example
• Dinosaurs went extinct 65.5 Ma.
• So if you find a rock with dinosaur fossils, it
must be older than 65.5 Ma!
59
Index fossils
• All fossils help us date rocks, but some are
more useful.
• The more useful ones are called index
fossils.
60
Index fossils
• Which of these things would make a fossil
organism a good index fossil?
Widespread (found all over)
Found in only a small area
Rare
Common
Lived for a short time only
Lived for 100's of million of years
1
OOO
Dashboard
Calendar
To Do
Notifications
Inbox
1:09
Relative dating 4U.pdf
&
60
Index fossils
• Which of these things would make a fossil
organism a good index fossil?
Widespread (found all over)
Found in only a small area
Rare
Common
Lived for a short time only
Lived for 100's of million of years
61
Question
• Look at the diagram on the next slide.
• The drawing shows the rock types and
fossils found in four locations.
• Which fossil would be the best choice to
use as an index fossil for these rocks?
• Why? Explain your reasoning to your
partner (or just to yourself).
62
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display,
North
West
East
South
Sandstone A
Limestone A
4 Shale A
Sandstone B
Limestone B
Shale B
Gneiss
Limestone C
Coal
Fossil 1
Fossil 2
Fossil 3
GSA GEOLOGIC TIME SCALE
1.40
MESOZOIC PALEOZOIC PRECAMBRIAN
63
CENOZOIC
ERA
PERICO
NEOPRO
TONIAN
STENIAN
ALBAN
MEBORD
TERORDIC
ставен
BRIGALIAN
Geologic Time Scale
Divisions of Earth's History
1
OOO
Dashboard
Calendar
To Do
Notifications
Inbox
1:09
<
Relative dating 4U.pdf
☆
66
Question
• The Earth is 4.6 billion years old.
• The Phanerozoic is the last 541 million
years.
• So what percentage of Earth's history is
represented by the Precambrian? (See fig.
18.25 on p. 486.)
67
Eras
• Eons are divided into eras.
• Look in your book. What are the three eras
of the Phanerozoic Eon?
68
Periods
• Eras are divided into periods.
• Look in your book. What are the three
periods of the Mesozoic Era?
69
Epochs
• Periods are divided into epochs.
• Look in your book. What are the two
epochs of the Quaternary Period?
1
OOO
Dashboard
Calendar
To Do
Notifications
Inbox
1:09
Relative dating 4U.pdf
GSA GEOLOGIC TIME SCALE 1.4.0
MESOZOIC PALEOZOIC PRECAMBRIAN
63
CENOZOIC
AGE
ERA
PERIOD
NEOPRO
TONIAN
STENIAN
оно.
BOTAS
BURDIGALIAN
Geologic Time Scale
Divisions of Earth's History
LUTETIAN
SIITTI
VAREN
THANETIAN
SGLANDUAN
DANAN
THE GEOLOGICAL SOCIETY
OF AMERICA
'The Poe is divided into our us, but was some bare also be inclytheists 1.71 Medom 1. i 13 and Laterno
Walkar Dawan, Juving 5. adabad, LI.com, 2012. Gadiogic TS.Gagal Society of musica, 1.002 CORE 2 The Geological Society mala
REFERENCES.COM, K., Sd Cast L.2012.
Saligraphic Data Carrinca ce Sig.phys. Choose
Grad, S. 16 SchD, 2012. The Cologie Time Salle 2012 STOEBEST-SOUS-1.000
64
Eons
• The largest unit of geologic time is the eon.
• Earth has four eons: Hadean, Archean,
Proterozoic, and Phanerozoic.
• (Some books leave out the Hadean.)
65
Precambrian
• Geologists tend to lump the Proterozoic,
Archean and Hadean Eons together, into
the "Precambrian.”
Why do you think this is?
66
Question
• The Earth is 4.6 billion years old.
• The Phanerozoic is the last 541 million
years.
• So what percentage of Earth's history is
represented by the Precambrian? (See fig.
1
Dashboard
Calendar
To Do
Notifications
Inbox
1:09
Relative dating 4U.pdf
☆
st
69
Epochs
• Periods are divided into epochs.
• Look in your book. What are the two
epochs of the Quaternary Period?
70
Questions
• Look at page 486.
• Are the periods all the same length of time?
What about the eras and eons?
• Why is that?
71
Questions
• Look again at page 486.
• The Precambrian isn't divided into periods.
• The Paleozoic and Mesozoic aren't divided
into epochs.
• Why is that?
GSA GEOLOGIC TIME SCALE 40
MESOZOIC PALEOZOIC PRECAMBRIAN
72
CENOZOIC
ADE
AGA
PER
NEORD
TOMAN
STEIN
ALBAR
MEBORD
TERORDIC
BOTASUN
GALVAN
AQUITAIN
STATIERAN
DATTIAN
OROSRIAN
PALEOPRO
RUPELIN
HACIAN
PRIBONIA
BARTORAN
LUTETIN
ARDHEAN
YPRESIN
PWLED
VINH
1
OOO
Dashboard
Calendar
To Do
Notifications
Inbox
1:09
Relative dating 4U.pdf
☆
st
into epochs.
• Why is that?
1.4.0
GSA GEOLOGIC TIME SCALE
MESOZOIC PALEOZOIC PRECAMBRIAN
72
CENOZOIC
AGE
AGE
AGE
CRA
PERIOD
NEOPRD
LANCARAN
CRVENAN
TONIAN
TORTORAN
STENA
SERRALLIAN
LANGEN
ALBAN
MESOPRO
TEROR
BOTAS
BURDIGAN
ΑΡΤΑ
GALVAN
ADUITAN
STATIERAN
DUTAN
TERUS
BELIAN
VACAN
EVEN
SERIAN
PAD
ECOARCHE
LUTETIN
MESO
RHATIAN
YPAESAR
ARDEAN
DANIAN
THE GEOLOGICAL SCXCIETY
OF AMERICA
Telecame
down the What was om te
do
Gitar. J. Bourg SA, and cod LS2, Galege Twengalackya keris, SBRIE The Geological Society
The Comic Walked Pican thereof the hanc Rossidable to the 2012 and Chat 20comprend paket beds
Founded to remember for the new android pe fere Gescind to procedere Gebe po
BERRIES
CITOPL Delerational Care este cel poate de Chat
Grada OJ. Schmidt, The Badogle Tree Boon, USA. DE ----
73
The End
1
000
Dashboard
Calendar
To Do
Notifications
Inbox