Dr. Tess Consulta
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TYPES OF CRUSTS
• Oceanic crust is thin and composed of basalt
• The continental crust is composed mainly of lighter
• Continental crust is thinnest in areas like the Rift Valleys
of East Africa and in an area known as the Basin and
Range Province in the western United States.
PROCESSES INVOLVED IN
breakdown and alteration of rocks and
minerals at or near the Earth's surface into
products that are more in equilibrium with
the conditions found in this environment.
• occurs when the two surfaces of water
and compound meet.
• involves the reaction between mineral
ions and the ions of water (OH- and H+)
• results in the decomposition of the
• reaction that
• Makes the rocks
• allows for the
acceleration of other
surface area for
• active when the
• decomposition of
because of its
• water + carbon
dioxide + calcite
calcium ion and
• cause sinkholes
and karst features
as well as
statutes and grave
• physical grinding of
• pits that have been
eroded into the rock
• rock is repeatedly
wetted and dried as
dissolve from the
rock then grow
when it is dried -
• two types of crystal
growth that occur;
they are ice and salt.
• water expands when
it freezes. the
cycles of freeze-
• heating causes rock
to expand, cooling
• different minerals
expand and contract
at different rates.
• typically happen in
• During the process
of weathering, hard
or resistant material
is left behind while
softer material is
scoured out by the
action of wind and
• rock breaks apart in
layers that are
parallel to the
• as rock is
expands (due to the
• Burrowing animals
• Increase of carbon
• Chelation –
• deformation of the Earth's crust.
• most obvious evidence of diastrophic
movement can be seen in sedimentary
rock where bent, broken or non-
horizontal strata provide visual proof of
TWO TYPES OF MOVEMENTS
• occurs when one or a stack of originally flat
and planar surfaces, such as sedimentary
strata, are bent or curved as a result of
plastic (i.e. permanent) deformation
• planar rock fractures which show evidence
of relative movement.
• Earthquakes are caused by energy release
during rapid slippage along faults.
• The addition of glacial ice on the Earth's surface
causes the crust to deform and sink (a). When the
ice melts, isostatic rebound occurs and the crust
rises to its former position before glaciation (b and
c). A similar process occurs with mountain building
and mountain erosion
• The plates move in
ways. They either
slide past one
together, or pull
apart from each
• Convection currents in Earth's mantle and
their role in oceanic crust formation and
Earthquakes and Volcanoes play
a fascinating role in creating
and changing the landscapes of
An earthquake is a sudden movement of
the Earth, caused by the abrupt release
of strain that has accumulated over a
The trembling or shaking movement of the
earth's surface may be minor tremors or
usually begin with slight tremors but
rapidly take the form of one or more violent
shocks, and end in vibrations of gradually
diminishing force called aftershocks.
The subterranean point of origin of an
earthquake is called its focus; the point on
the surface directly above the focus is the
Shifting and Sliding
Along the boundary separating
any two plates, the relative
motion between the plates can
be classified into one of 3
Divergent Motion: Movin' Apart
This is the most common kind of motion
along the mid-ocean ridges. This is a
system of undersea mountain ranges that
extends beneath the world's oceans and
connects together like the seams on a
Convergent Motion: Comin' Together
This is the most common kind of motion at
subduction zones. This motion happens where
dense oceanic plates colide and slide beneath
This is the motion of the earthquake as
A good example of this type of motion is the
San Andreas Fault which runs through
Earthquakes create seismic waves are
just like waves of water moving across
the ocean and waves of air moving
across a field of wheat.
The P waves move in a compressional motion similar
to the motion of a slinky, while the S waves move in
a shear motion perpendicular to the direction the
wave is travelling.
Earthquakes generate several kinds of
seismic waves including P, for "Primary"
and S, for "Secondary" waves.
Some depend on the amount of damage caused by the
earthquake while others depend on the amount of seismic
energy emitted by the earthquake.
There are two popular earthquake scales.
The Mercalli Intensity Scale
(intensity / effect of
earthquakes on certain
The Richter Magnitude Scale
invented in China
A.D. 136 by a m
an named Choko.
Each dragon head held a ball
in its mouth, which, when
dropped due to the strong
shaking of an earthquake,
would fall into the open
mouth of the frog directly
By noting which frogs
contained balls after a
strong earthquake, it was
possible to determine how
the Earth had moved in
response to the earthquake.
early eastern seismoscope consisted of a copper vessel
with eight dragon heads attached to it, positioned
above eight frogs.
By the end of the 19th century, several
European inventors had constructed different
seismographs. Most were electromagnetic and
operated by suspending a magnetic mass, or
pendulum, within an electric coil.
Today's high-technology, digital seismographs
record ground shaking over a large band of
frequencies and seismic amplitudes.
They are called broadband since they record
frequencies from thousands of seconds to less
than a hundredth of a second.
old seismometers was limited by the amount of
movement possible between the mass, or
pendulum, and the seismometer housing.
Modern seismometers can record a wide range
of seismic signals, both very small and very
• a conical shaped hill or mountain built by
accumulations of lava flows, tephra and volcanic ash.
• has its origin from the name of Vulcan, a god of fire in
What is a Volcano?
The processes that create volcanoes and other volcanic
Most volcanoes occur where two
plates meet. When two plates move
apart causing a gap, hot molten rock -
called magma - rises up between
them. This type of volcano occurs on
the ocean floor and is mostly invisible.
If the amount of magma is large
enough, it rises above the surface of
the ocean and an island is created.If
two plates collide and one plate is
forced beneath the other plate, the
friction makes the first melt and
magma rises up. Only a few
volcanoes on earth are formed like
this, but their eruptions are the most
violent and dangerous ones.
Sometimes volcanoes also form in
the middle of the plates which are
called hotspots. These are places that
are connected by channels to the hot
YouTube - How Volcanoes Fo
This classification is based on
the geomorphic form, magma
chemistry, and the explosiveness
of the eruption.
five different types of volcanoes.
Least explosive type of volcano.
Produces a very basaltic magma with horizontal
Shaped like a bowl or shield in the middle with long
gentle slopes made by the lava flows.
Built up of successive layers of high viscosity lava
This type of volcano is built slowly and can have
multiple vents producing lava flows.
Largest active volcano in the world.
5 1/2 miles high (3 miles under water and
2 1/2 miles above sea level). Almost 5
miles of this volcanic structure is buried
into the Pacific plate below ground level
which if included makes this structure
about 10 miles in height!
A shield volcano.
A cone structure built by an accumulation of loose
bits of magma called scoria that fall around a vent
or crater after being expelled during moderately
A small volcano between 100 and 400 meters tall.
Has steeply sloped sides
Also known as stratovolcano.
It is a cone shaped mountain with steep, smooth,
barren slopes often with a single plume of smoke
emitted from a single central vent. It is composed
of alternating layers or strata of material created
by pyroclastic (lava) flows.
They form when huge amounts of magma erupts out
of sub-surface magma chambers. The removal of
magma leaves a void below the surface and the top
collapses in to form the caldera. The resulting basin-
shaped depression is roughly circular and is usually
several kilometers or more in diameter. The lava
erupted from caldera volcanoes is very viscous and
generally the coolest with temperatures ranging from
650°C to 800°C and is called rhyolitic magma.
Although caldera volcanoes are uncommon, they are
the most dangerous.
Volcanic hazards from this type of eruption include
tsunami from caldera collapse, large pyroclastic
surges and widespread ash fall.
types of volcano.wmv
• Active volcano
– Erupts regularly or showing signs of unrest.
• Dormant volcano
– also called "Sleeping" volcanoes because it is
presently inactive, but could erupt again.
• Extinct volcano
– has not had an eruption for at least 10,000
years and is not expected to erupt again in a
comparable time scale of the future.
• hotspot theory- A hotspot is located in the
middle of a plate (below it). When the
hotspot emits magma, it will form a
volcano. As the plate moves, the volcano
located on the plate moves together with it.
It is then cut off from the magma source
which is the hotspot, and it becomes extinct.
How do active volcanoes become
• Helps in maintaining the biogeochemical
• Helps in cooling the atmosphere
Effects of volcanic eruptions
• Add nutrients to soil through weathering
process of volcanic rock
• Create new islands
Effects of volcanic eruptions
– Volcanic features like maria, sign of
past lava flow
– 90% basalt
Volcanoes on other
– Four of several extinct volcanoes are
Arsia Mons, Ascraeus Mons, Hecates
Tholus, Olympus Mons, and Pavonis
Volcanoes on other
– Io-most volcanically active
– Europa- its volcanic activity is
entirely in the form of water, which
freezes into ice on the frigid
Volcanoes on other