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8-2 & 8-3 NOTES
L A N D F O R M S AT P L AT E B O U N D A R I E S
A N D M O U N TA I N B U I L D I N G
L A N D F O R M S C R E AT E D B Y P L AT E M O T I O N
• The large slow moving plates have so much force that
they can form tall mountains and deep valleys.
• At plate boundaries, three types of stresses can
produce different types of landforms.
• Tension
• Compression
• Shear
L A N D F O R M S C R E AT E D B Y
COMPRESSION
• The largest landforms on Earth are
produced by compression at
convergent plate boundaries.
• The collision of two continental
plates causes tall mountains to form.
• Takes millions of years to
form
• ex: The Himalayas
LANDFORMS
C R E AT E D B Y
COMPRESSION
• Through subduction, two plates can collide forcing the
denser plate into Earth’s mantle creating a ocean trench.
• Ocean trenches are deep, underwater troughs.
• Volcanic mountains can form in the ocean where plates
converge and one plate subducts under another.
• Volcanic arc: a curved line of volcanic islands that
forms parallel to a plate boundary.
L A N D F O R M S C R E AT E D B Y T E N S I O N
• Where plates move apart, tension stresses stretch Earth’s crust.
• In the ocean, tension stresses produce a(n) mid-ocean ridge along
divergent plate boundaries.
• When divergent boundaries occur between two continental plates, tension
stresses cause continental rifts.
• Continental Rift: an enormous split in the Earth’s crust to form.
• At the continental divergent plate boundary, tension stresses create
faults where large blocks of crust move downward creating a rift
valley.
• Fault: a crack or a fracture in Earth’s lithosphere
L A N D F O R M S C R E AT E D B Y S H E A R
STRESSES
• As two plates slide past
each other, shear stresses
occur at transform
boundaries.
• Shear stresses at
transform boundaries
produce faults.
T R A N S F O R M F A U LT S
• Transform faults form where
tectonic plates slide
horizontally past each other.
• Some transform faults
form perpendicular to
a mid-ocean ridge,
separating the midocean ridge.
• Fault Zone: an area with
many fractured pieces of
crust along a large fault.
T H E M O U N TA I N - B U I L D I N G C Y C L E
• Mountain ranges form and change slowly over
millions of years.
• Many plate collision occur forming mountains made
up of many different types of rocks.
C O N V E R G E N T P L AT E S
• When plates collide at a(n) plate boundary, a
combination of folding, faulting, and uplift form
mountains.
• When two continents converge over millions of years,
the forces become inactive, forming one continent.
• With no compression at a convergent plate
boundary, the mountains stop growing.
COLLISIONS AND RIFTING
• The movement of tectonic plates, causes the
continents to always be changing.
• A divergent plate boundary that forms on a continent
often forms close to the place where two plates first
collided.
• Eventually plate movement changes and the
continents collide again.
W E AT H E R I N G
• As a mountain stops forming
weathering continues by
rounding the peaks and
lowering the elevation.
• ex: The Appalachian
mountains are not as
tall and rugged as the
Rocky mountains.
EROSION AND UPLIFT
• As a mountain erodes, the root under it must rise to
restore the balance between what is left of the
mountain and how it floats on the mantle.
• Rocks deep under continents rise slowly toward
Earth’s surface.
• In old mountain ranges, metamorphic rocks that
formed deep below the surface are exposed on
the top of mountains.