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Landforms, Rocks, and
Minerals
Chapter 7
What Makes the Crust Move?
• Earth’s crust is constantly moving, if not in
one place then in another. Sometimes it
moves quickly enough to be seen and felt
(such as an earthquake).
Earthquake
• Earthquakes are related to cracks in the
crust called faults. The faults may have
formed from earlier earthquakes.
Sometimes they form while the earthquake
happens.
Earth’s Vibrations
• During an earthquake vibrations travel through
the crust. The farther away people are from the
earthquake, the harder it is for them to feel the
vibrations.
• The vibrations that move
through the Earth’s layers
are called seismic waves.
• These vibrations are measured
on a machine called a
seismograph.
Fault
Seismograph
• A seismograph, or seismometer, is an
instrument used to detect and record
earthquakes. Generally, it consists of a
mass attached to a fixed base. During an
earthquake, the base moves and the mass
does not.
Not all motion happens
along faults. Often,
layers of the crust
bend. Bending, like
motion along a fault,
may happen gradually
over time.
To measure crust
movement, surveyors
measure elevation—
how high a place is
above sea level.
They leave plaques called
bench marks that tell the
exact location and elevation of
a place. When some bench
marks are remeasured, they
are found to have risen or
sunk.
• Geologists are
scientists who
study the
Earth.
Tools of the Trade
Geologist Brunton Pocket Transit
Geologist Estwing Rock Hammer
Geologist Outfit
Earth’s Layers
The Earth is composed of four
different layers.
1. Crust – Earth’s outermost layer
that is thinnest under the oceans
and thickest through the
mountains.
2. Mantle – largest layer of Earth’s
interior that lies above the outer
core and is solid yet flows slowly.
3. Outer core – layer of Earth that
lies above the inner core and is
thought to be composed mostly
of molten metal.
4. Inner core – solid, innermost
layer of Earth’s interior that is the
hottest part of the Earth and
experiences the greatest amount
of pressure.
Clues to Earth’s Interior
Scientist or geologist use indirect
observations to gather clues about what
the Earth’s interior is made of and how it is
structured. Geologist studies:
1. Waves
2. Rock Clues
Earth’s Plates
• The rigid, upper part of Earth’s mantle and
the crust is called the lithosphere.
Plates – The moving pieces of the
relatively rigid outer layer of the Earth (the
lithosphere), made up of the crust and
upper mantle, which contain the continents
and ocean floors.
Plate Boundaries (3 types):
Plate boundaries – the places where the
edges of different plates meet.
1. Mountains – landforms that extends
above the surrounding terrain.
2. Rift valleys – elongated depressions.
3. Faults – large fracture in rocks along
which movement occurs.
(Fracture – a break in a rock formation due to structural
stresses.)
• The movements of the plates are fairly
slow, often taking more than a year to
creep a few centimeters.
Plates
Slow
Creep
Plates That Move Apart
• Subduction – a type of plate movement
that occurs when one plate sinks beneath
another plate.
Three Types of Convergent Plate
Boundaries
1.
2.
3.
Continental-continental collisions
Continental-oceanic collisions
Oceanic-oceanic collisions
Uplift of Earth’s Crust
There are four main types of mountains:
1. Fault-block
2. Folded
3. Upwarped
4. Volcanic
http://pirate.shu.edu/~schoenma/mountains.htm
Fault-Block Mountains
• Fault-block mountains form from pulling forces. They
are sharp jagged mountains made of huge, tilted blocks
of rock that are separated from surrounding rock by
faults and form because of pulling forces.
(Fault – large fracture in rock along which
movement occurs.)
Folded Mountains
• Folded mountains are mountains formed
by the folding of rock layers caused by
compression forces.
Upwarped Mountains
• Upwarped mountains form when forces
inside Earth push up the crust.
Volcanic Mountains
• Volcanic mountains are mountains that
forms when magma is forced upward and
flows onto Earth’s surface.
http://www.arenal.net/photo/latest/2005-september/
Parts Of A Volcano
What type of mountains make up the
Hawaiian Islands?
Volcanic Mountains
Other Types Of Uplift
• According to the principal of isostasy, the crust and lithosphere are
able to float on the mantle.
• The principle of isostasy relates to the buoyancy of rocks.
(Buoyancy is the tendency of a body to float or rise when
submerged in a fluid.)
The End
Does all of this drive you apes?