Earth and Life Science Lectures Week 5 DISCLAIMER: Media files courtesy to their rightful owners

3. PHOTO: Geology In
▸ from low grade to high grade

4. ▸grains are arranged in planes
or bands
▸grains are not arranged
▸usually only one mineral
PHOTO: Mindat.org
PHOTO: gotbooks.miracosta.edu

5. ▸Enhance the metamorphic process
▸It increases with depth, and the buried
rocks are subjected to the force or stress
▸It provides the energy to drive the
chemical changes

6. Magma
chamber
Extrusive igneous rocks cool quickly and as a
result, these rocks are fine grained or has lack of
crystal growth.
Intrusive igneous rocks are formed
from magma that cools slowly and
as a result, these rocks are coarse-
grained.

7. Felsic
made of light-colored, low-
density minerals such as
quartz and feldspar
Mafic
made of dark-colored,
higher-density minerals
such as olivine and
pyroxene.

8. Intermediate
have compositions
between felsic and mafic
Ultramafic
contain more than 90%
mafic minerals and have
very few light, felsic
minerals in them.

9. 1. Explain how the movement of plates leads to the
formation of folds and faults. (S11/12ES-Id-22)
2. Describe how layers of rocks (stratified rocks) are
formed. (S11/12ES-Ie-25)
3. Describe the different methods (relative and
absolute dating) to determine the age of stratified
rocks. (S11/12ES-Ie-26)

10. Explain how the movement of plates leads to the formation
of folds and faults. (S11/12ES-Id-22)
LESSON 1

11. are pieces of
Earth's crust and
uppermost
mantle, together
referred to as the
lithosphere.

12. The plates are
around 100 km (62
mi) thick and consist
of two principal types
of material: oceanic
crust and continental
crust

13. the scientific
theory explaining
the movement of
the earth’s crust.

14. the movement
of the plates
that make up
Earth’s crust

17. Cold, sinking
lithosphere at the
edges of a tectonic
plate pulls the rest
of the plate across
Earth’s surface.

18. Gravity pulls newly formed lithosphere downward
and away from the mid-ocean ridge. The rest of the
plate moves because of this force.

19. Convection currents are
produced when hot
material in the mantle
rises toward the surface
and colder material
sinks. The currents pull
plates over Earth’s
surface.

20. when two continental plates are shoved
together

21. when one plate plunges beneath another

22. when two plates are pushed apart

23. when two plates slide past each other

24. The movement of crust causes stress which can result
to formation of faults. A fault is formed in the Earth's
crust as a brittle response to stress.

25. The sense of stress determines the type of fault that
forms, and we usually categorize that sense of stress in
three different ways:

26. correlate with the three types of plate boundaries
happens at convergent plate boundaries
where two plates move toward each other

27. happens at divergent plate boundaries where
two plates are moving away from each other.

28. experienced at transform boundaries where
two plates are sliding past each other

30. Folding occurs when tectonic
processes put stress on a rock, and
the rock bends, instead of
breaking.

31. This can create a variety of
landforms as the surfaces of the
folded rocks are eroded.

32. are folds shaped like an arch
are shaped like the letter 'U'

33. 1. Sediments accumulate in
shallow seas or depressions
known as GEOSYNCLINES as
rivers enter those areas.
2. This creates a sea or lake bed of
layered sedimentary rocks as
compression takes place.
3. Two plates move together
because of convection currents
in the mantle.
4. This starts to crumple the rocks
together.

34. 5. The rocks start to form
folds which have anticlines
and synclines, which are
pushed upwards to form
fold mountains
6. These mountains are then
subject to erosion,
weathering and mass
movement (denudation).

35. Describe how layers of rocks (stratified rocks) are
formed. (S11/12ES-Ie-25)
Lesson 2

37. Sedimentary rocks are formed by the
accumulation of sediments from older rocks
that have been broken apart by water or wind.
CONGLOMERATE MUDSTONE SHELL LIMESTONE

38. ● organic materials, or in other words, the
remains of once-living organisms,
● chemical precipitates, which are materials that get
left behind after the water evaporates from a
solution.
● fragments of other rocks that have been worn
down into small pieces, like sand,
Sediments may include:
Sedimentary rocks are formed by the
compaction of sediments

40. Erosion and
weathering include
the effects of wind
and rain, which
slowly break down
large rocks into
smaller ones.

41. Erosion and
weathering
transform boulders
and even mountains
into sediments, such
as sand or mud.

42. Dissolution is a form
of weathering—
chemical weathering.
With this process,
water that is slightly
acidic slowly wears
away stone.
Windows 10 Spotlight images

43. Precipitation is the
formation of rocks
and minerals from
chemicals that
precipitate from
water.

44. For example, as a lake
dries up over many
thousands of years, it
leaves behind mineral
deposits.

45. Lithification is the process
by which clay, sand, and
other sediments on the
bottom of the ocean or
other bodies of water are
slowly compacted into
rocks from the weight of
overlying sediments.

46. LITHIFICATION (DIAGENESIS)
▸ the process that turns sediment into rock

47. STAGES OF LITHIFICATION
1. COMPACTION
▸ occurs as the weight of the overlying material
increases.
▸ forces the grains closer together, reducing pore
space and eliminating some of the contained
water.
▸ Some of this water may carry mineral
components in solution, and these constituents
may later precipitate as new minerals in the
pore spaces.

48. STAGES OF LITHIFICATION
2. CEMENTATION
▸ Binding of the individual particles together to
form sedimentary rocks.

49. Clastic sedimentary rocks are made up
of pieces (clasts) of pre-existing rocks.
Pieces of rock are loosened by
weathering, then transported to some
basin or depression where sediment is
trapped. If the clastic sediment is
buried deeply, it becomes compacted
and cemented, forming sedimentary
rock.
CLASTIC
CLASSIFICATION OF
SEDIMENTARY ROCKS

50. Clastic sedimentary rocks may have particles ranging in size
from microscopic clay to huge boulders. Their names are
based on their grain size.
CLASTIC
CLASSIFICATION OF
SEDIMENTARY ROCKS
BRECCIA CONGLOMERATE SANDSTONE SILTSTONE SHALE

51. Chemical sedimentary rocks are formed
by chemical precipitation. This process
begins when water traveling through
rock dissolves some of the minerals,
carrying them away from their source.
CHEMICAL
CLASSIFICATION OF
SEDIMENTARY ROCKS

52. Eventually these minerals are
redeposited when the water evaporates
away or when the water becomes over-
saturated.
CHEMICAL
CLASSIFICATION OF
SEDIMENTARY ROCKS

53. EXAMPLES OF CHEMICAL
SEDIMENTARY ROCKS
ROCK SALT
IRON ORE
FLINT
DOLOMITE
LIMESTONE
CHERT

54. EXAMPLES OF CHEMICAL
SEDIMENTARY ROCKS
ROCK SALT
IRON ORE
FLINT
DOLOMITE
LIMESTONE
CHERT

55. Biologic sedimentary rocks
form from once-living
organisms. They may form
from accumulated carbon-rich
plant material or from deposits
of animal shells.
BIOLOGIC/ORGANIC
CLASSIFICATION OF
SEDIMENTARY ROCKS

56. EXAMPLES OF BIOLOGIC/ORGANIC
SEDIMENTARY ROCKS
CHALCOPYRITE-DOLOMITE
ORGANIC LIMESTONE
COAL

57. Lesson 3
Describe the different methods (relative and absolute dating) to
determine the age of stratified rocks. (S11/12ES-Ie-26)

59. STRATIGRAPHY
a branch in geology which studies
the chronology of events and
changes, along with the develop-
ment of organisms, which have
determined the development of the
Earth from when it became an
independent spatial body until
today.

60. DATING METHODS
Relative Dating
▸ a method of arranging
geological events based on
the rock sequence.
▸ in determining the relative
age of a rock, the data from
sedimentary rocks are
generally used.

61. DATING METHODS
Relative Dating
▸ Relative age of magmatic and
metamorphic rocks is
determined according to their
relation with sedimentary
rocks.

62. DATING METHODS
Relative Dating
▸ Relative dating cannot
provide actual numerical
dates of rocks.
▸ It only tells that one rock is
older than the other but does
not tell how old each of the
rock is.

63. Nicholas Steno, 1600s
▸ studied the relative positions
of sedimentary rocks.
▸ He discovered that they settle
based on their relative weight
or size in a fluid.
▸ The largest or heaviest
particles settle first, and the
smallest or the lightest
particles settle last.

64. ▸ Any slight changes in the
particle size or
composition may result in
the formation of layers
called beds.
▸ Layering or bedding is a
distinct quality of
sedimentary rocks.
▸ The layered rocks are also
called strata.

65. 1) The Law of Superposition
▸ in any sequence of layered
sedimentary rocks, the top
layer is younger than the
bottom layer.
Principles of Relative Dating

66. 2) The law of original horizontality
▸ states that most sediments were originally laid
down horizontally.
▸ the rocks that were tilted may be due to later
events such as tilting episodes of mountain
building.

67. 3) The law of lateral continuity
▸ states that rock layers extend laterally or out to
the sides.
▸ Erosion may have worn away some parts of the
rock, but the layers on either side of the eroded
areas still match.

68. 4) The law of cross-cutting
relationship
▸ states that fault lines
and igneous rocks are
younger features that
cut through older
features of rocks.

69. In the diagram, the
igneous dike D must be
younger than fault A and
igneous intrusion B,
because it cuts across
these (and other) features.

70. 5) Principle of
unconformities
▸ A gap in the sequence of
rock layers is called an
unconformity

71. Types of unconformities
1. Nonconformity
▸ A boundary between
non-sedimentary rocks
below and sedimentary
rocks above

72. Types of unconformities
2. Angular unconformity
▸ A boundary between two
sequences of sedimentary rocks
where the underlying units have
been tilted (or folded) and
eroded prior to the deposition of
the younger units.

73. Types of unconformities
3. Disconformity
▸ A boundary between two
sequences of sedimentary rocks
where the underlying units have
been eroded (but not tilted)
prior to the deposition of the
younger units.

74. Types of unconformities
4. Paraconformity
▸ A time gap in a sequence of
sedimentary rocks due to non-
deposition. The time gap does
not show up as an angular
conformity or a disconformity.

75. Types of unconformities
4. Paraconformity
▸ A time gap in a sequence of
sedimentary rocks due to non-
deposition. The time gap does
not show up as an angular
conformity or a disconformity.

76. 6) Principle of inclusions
▸ Sedimentary rocks can
contain clasts of other
rocks (such as pebbles in a
conglomerate), or igneous
rocks can contain xenoliths
(foreign rock fragments)
which were ripped from
surrounding rocks by the
magma.

77. 7) Principle of Fossil
Succession
▸ Assemblages of fossils contained
in strata are unique to the time
they lived, and can be used to
correlate rocks of the same age
across a wide geographic
distribution.
▸ Assemblages of fossils refers to
groups of several unique fossils
occurring together.

78. Principle of Fossil Succession
▸ is a stratigraphic principle where geologists use
fossils in the rock to help interpret the relative
ages of the rock.

80. radioactive
decay

82. RADIOMETRIC
is the process of
determining the absolute
age of a sample based on
the ratio of parent isotope
to daughter isotope.
DATING

83. RADIOMETRIC
In order to use radiometric
dating, you need to know the
half-life of the parent
isotope. The half-life of a
radioactive isotope is how
long it takes for half of a
sample of the isotope to
DATING

84. For example, imagine
that a parent isotope
has a half-life of 10,000
years. A sample of this
isotope has a mass of
12 mg. After 10,000
years, only one-half, or
6 mg, of the sample
will be left.

85. Isotopes Used for
Radiometric Dating
▸ Potassium-40 is one isotope that is
often used in radiometric dating. It
has a half-life of 1.3 billion years. It
decays to produce the daughter
isotope argon-40. Scientists usually
use the potassium-argon method to
date rocks that are older than about 1
million years.
1. POTASSIUM-ARGON METHOD

86. ▸Uranium-238 is also used
for radiometric dating. It
has a half-life of 4.5 billion
years. It decays to produce
lead-206. Scientists use the
uranium-lead method to
date rocks that are older
than about 10 million
years.
2. URANIUM-LEAD METHOD

87. ▸Rubidium-87 is also used for
radiometric dating. It has a half-
life of about 48 billion years. It
decays to produce the daughter
isotope strontium-87. The half-
life of rubidium-87 is very long.
Therefore, this method is only
useful for dating rocks older
than about 10 million years.
3. RUBIDIUM-STRONTIUM
METHOD

88. ▸Carbon-14 is a radioactive
isotope of the element
carbon. Carbon-14, along
with the other isotopes of
carbon, combines with
oxygen to form the gas
carbon dioxide. Plants use
carbon dioxide to make
food.
4. CARBON-14 METHOD

89. ▸Therefore, living plants
are always taking in small
amounts of carbon-14.
Animals that eat plants
also take in carbon-14
from the plants.
4. CARBON-14 METHOD

90. ▸When a plant or animal
dies, it stops taking in
carbon-14. The carbon-14
already in its body starts
to decay to produce
nitrogen-14. Carbon-14
has a short half-life: only
5,730 years.
4. CARBON-14 METHOD

91. ▸Therefore, this method
can be used to date the
remains of organisms that
died in the last 50,000
years
4. CARBON-14 METHOD