I hope you can get more ideas on my presentation. This my first report as a education student at HOLY CROSS COLLEGE

1. Geological
Forces
of
the
Earth

2. Diastrophism

3. It pertains to any movement of the solid part of the
Earth.
• The movement may be strong and sudden that we
feel the shaking of the Earth’s surface, we call this
Earthquake
Tectonism
Leads to the formation of continents and ocean
basins, mountain systems, plateaus, rift valleys,
and other features.

7. Uplift and Subsidence
Vertical movements in the crust are divided into two types—
uplift and subsidence.
Uplift
 The rising of regions of the Earth’s crust to higher
elevations.
Subsidence
 The sinking of regions of the Earth’s crust to lower
elevations.

8.  Uplifting of Depressed Rocks
› Uplift can occur when large areas of land rise without
deforming.
 Areas rise without deforming is process known as
rebound.
› When the crust rebounds, it slowly springs back to
its previous elevation.

9.  Subsidence of Cooler Rocks
› Rocks that are hot take up more space than cooler
rocks.
 The lithosphere is relatively hot at mid-ocean ridges, but
cools as it moves farther from the ridge.
 As it cools,
› The oceanic lithosphere takes up less volume and the
ocean floor subsides.

12. Theory of Isostasy

13.  Isostasy can be explained as the balancing of
forces between the effects of gravity on the mass
of a section of earth and the resistance of that
mass to sinking into the mantle of the earth.
 The simplest analogy of isostasy is icebergs (this
is based on Archimedes’ Principal).
 This explains why the wearing down of mountains
and the filling up of the ocean basins have not
resulted on a leveled surface over the whole
earth.
 As vertical adjustments take place, landmasses
are folded, buckled and thrusted.

14. Simple Analogy:

15. Example:
 North
Greenland
ford cliffs

16. TRIVIA:
 The general
term 'isostasy'
was coined in
1889 by the
American
geologist
Clarence
Edward Dutton.

17. Theory of Contraction
› because it is cooling and the great pressure
squeezes parts of the earth into a smaller volume.
› Gravity draws the crust inward causing it to buckle,
bend and trench.

18.  Shrinking
resulted in a
reduction in
the Earth’s
diameter while
the
circumference
remained
unchanged due
to folding and
buckling of the
crust

19. Theory of Convection

20.  According to this
theory, convection
currents are set in the
crust and heat comes
from the disintegration
of radioactive elements.
 As heat accumulates,
rocks become plastic
and moves upward
causing the surface of
the earth to bulge.

21.  convection
within the
Earth's mantle
pushes the
plates
 movement of a
fluid, caused
by differences
in temperature

22. Continental Drift Theory

23.  Proposed by a German meteorologist and
geophysicist, Alfred Wegener.
 Wegener hypothesized that there was an
original, gigantic supercontinent 200 million
years ago, which he named Pangaea,
meaning "All-earth".
 Pangaea was a supercontinent consisting of
all of Earth's land masses.
 Pangaea started to break up into two smaller
supercontinents, called Laurasia and
Gondwanaland, during the Jurassic period
 Continents were joined in a super-continent,
called Pangaea (all lands). Over a vast period
of time, the continents drifted apart to their
current locations.

25.  Numerous
geological
similarities
between
South
America
and Africa.

26. TRIVIA:
 Continental
Drift theory was
first presented
by Alfred
Wegener who
died two days
after his 50th
birthday.

27. Theory of Expansion

28.  Earth is physically expanding in
diameter, mass, or both.

29.  An Australian
geologist who was
an early advocate
of the theory of
continental drift.
His work on plate
tectonics
reconstructions led
him to develop the
Expanding Earth
hypothesis.

31. Deformation of Rocks
 Changes in a rock’s shape due to stress
De = “undo” Form = “shape” –tion = “process of”

32. Whether a material bends or breaks depends on:
1.How much stress is applied to the material.
2.Process by which the shape of a rock
changes because of stress.
3.Rock layers bend when stress is placed on
them.
4.When enough stress is placed on rocks,
they can reach their elastic limit and break.

33. 2 Major Types of
Structural Deformation
 Fold
 Fault

34. Folding

35.  Folding
› The bending of rock layers because of stress in the
Earth’s crust.
 Types of Folds
› Depending on how rock layers deform, different
types of folds are made.
 The major types of folds are
1. Anticlines
2. Synclines
3. Monoclines.

36.  Anticlines are upward-arching folds.
 Synclines are downward, troughlike folds.
 In a monocline, rock layers are folded so that
both ends of the fold are horizontal.

37. Anticline
 oldest rocks occur in the core of a fold
 Caused by compressional stress
 A-shaped

39. Syncline
 youngest rocks occur in the core of a fold
 Caused by compressional stress
 U-shaped

42. Monocline
 A fold that has both ends of the fold still
horizontal.
 There is a middle portion that bends
downwards.

43. Dip and Strike

45. Pitching Fold

47. Joints and Fissures

49. Faulting

50.  Fault
› The surface along which rocks break and slide past
each other.
› Some rock layers break when stress is applied.
 Fault blocks
› The blocks of crust on each side of the fault.
 When a fault is not vertical, its two sides are either a
hanging wall or a footwall.

53. Types
of
Faults

54. Dip Slip Faults - These are faults where the major
movement is vertical.
NORMAL FAULT - occurs when the
crust is extended. Also called as
extensional fault or gravity fault.
The hanging wall moves
DOWNWARD, relative to the
footwall.
• REVERSE FAULT - is the opposite of
a normal fault — the hanging wall
moves UPWARD relative to the
footwall. Reverse faults indicate
shortening of the crust.

56. Normal Faults
Tension forces in Earth's crust cause normal
faults.

57. REVERSE FAULT

58. • STRIKE-SLIP FAULT - It is usually near vertical and the
footwall moves either left or right or laterally with very little
vertical motion. Strike-slip faults with left-lateral motion are
also known as SINISTRAL faults. Those with right-lateral
motion are also known as DEXTRAL faults
•A special class of strike-slip faults is the transform
fault, where such faults form a plate boundary.
Transform faults runs along the boundary of a tectonic
plate and are also referred to as conservative plate
boundaries, as lithosphere is neither created or
destroyed.

62. Oblique Faults – These
are faults where the major
movements are both
horizontal and vertical.
For all naming distinctions,
it is the orientation of the
net dip and sense of slip of
the fault which must be
considered, not the
present-day orientation,
which may have been
altered by local or regional
folding or tilting.

63. Earthquakes

64. What is an
Earthquake?
Vibrations (seismic waves) within Earth materials are
produced by the rapid release of energy
 Earth’s crust is in constant motion because of
tectonic forces
 Earth’s crust can store elastic energy
 When forces exceed the elastic limits and
structural strength of the rocks, the rocks will
break and/or move producing vibrations that
travel outward in all directions

65. Earthquakes happen because the
ground is always moving
About 20 tectonic plates rub against each other,
floating above a layer of molten rock
Move about 5 inches per year (about as fast as our fingernails grow!)

66. Causes
of
Earthquake

67. Aftershocks and Foreshocks
• An aftershock is a small earthquake that
follows the main earthquake.
• A foreshock is a small earthquake that
often precedes a major earthquake.

68. Most earthquakes are produced by the rapid release of
elastic energy stored in rock that has been subjected to
great forces.
Short answer is that earthquakes are caused by
“FAULTING” a sudden lateral or vertical movement of
rock along rupture (break) surface.
EARTHQUAKE provide direct evidence of crustal
movement

69. Crustal Plates
Our planet's surface crust is relatively thin and extends to a
depth of about 70 kms (40 miles) beneath the oceans to about
150 km (90 miles) beneath the continents.
The crust is now known to be discontinous-- that is, it is
broken into a number of large fragments, called “PLATES”,
varying in width from few hundred to many thousands of miles.

71. Man-Made
Quakes

74. Seismic Waves
 Are sound travelling through and across the
earth that are produced by earthquakes.
Somes waves travel down through the earth
and other waves travel over the surface on
the ground. The surface waves travel faster
than the interior waves. The waves from a
large earthquake can be recorded on
instruments on the opposite side of the world,
having taken about 21 mins to pass right
through the eath.

75. 3
Types
of
Seismic
Waves

76.  P waves (primary waves) Compressional
wave
 Particles move back and forth in the same
direction as the wave
 Travels the fastest
 Can pass through solids and liquids (gases
also)
 Does not cause damage

77.  S wave (secondary wave, shear wave)
 Particles move at right angles to the direction of
the wave
 Travels slower than P waves
 Can pass through solids only
 Does not cause damage
 Strong movements can be recorded through
seismographs

78.  L wave (long wave, surface wave, ground
wave)
 Travel along the outer layer of the earth.
 Two kinds of R (or Rayleigh) waves and L (or
Love) waves, named after the 2 scientist who
first described them.
 This kind of wave is the last to arrive since it
travells relatively slowly.

79. How do we Measure
Earthquakes?
Earthquake waves are recorded by a
seismograph and the recording of waves on
paper is called seismogram

80. Effect
of
Earthquakes

81. Landslides

82. Fire

83. Seiches

84. Seismic Sea Wave of Tsunami
for “bay wave”

86. The
End
Reported by: Kclyn Canonizado-Pabellosa
BEED-1