Effects of Plate Tectonics
Think About It Date
Page G95 Page #
· Why are most high
mountain ranges
located at or near
plate boundaries?
Effects of Plate Tectonics
Investigate Date
Pages G96-98 Page #
1a. Describe any
differences between the
distribution of volcanoes
along plate boundaries
and within plate interiors.
1b. Describe any
differences between the
distribution of earthquakes
along plate boundaries
and within plate interiors.
2c. Describe and explain
the behavior of the
lava lamp.
2d. What do you think
are the similarities and
differences between the
behavior of the lava lamp
and the rise of magma
in the Earth?
3a. Record your group’s
hypothesis.
3b. Compare the
hypotheses you
developed in your group
with those of other
groups. Were their
hypotheses different
from yours and still
seemed reasonable?
4a. Under what two
types of plates is the
oceanic lithosphere
being subducted?
4b. What differences
between oceanic volcanic
arcs and continental
volcanic island arcs can
you see or infer from
the cross section?
4c. List two continental
island arcs and three
ocean island arcs.
4d. In which part of the
world are most volcanic
arcs located? What does
that suggest about the
plate-tectonics setting of
that part of the world?
5a. What is the shape of
the line on the globe?
Why are lines of
volcanoes called arcs?
5b. Explain why few
volcanoes occur very far
inland within a continent.
5c. If volcanic rock is
found far inland within a
continent, what is one
possible reason why it
is there?
6a. Where does it appear
that the hot spot
originated?
6b. Is it related to
subduction?
6c. Where does the hot
spot begin to produce a
pool of magma?
7a. Where are most hot
spots?
7b. Are they clustered
or randomly located?
7c. What famous area of
the continental United
States sits over a hot spot?
7d. What sits atop
another famous hot spot
in the United States?
Effects of Plate Tectonics
Digging Deeper Date
Page G100-103 Page #
Plate tectonics the field of study of plate motion
It refers to the building of features on Earth’s surface due to deformation caused by plate movements
Plate movements create:
•mountain ranges
•trenches
•rift valleys at or near plate boundaries
Oceanic trenches form where an oceanic plate is
subducted under another plate, it bends downward as it enters the subduction zone
the trench is the valley that is formed above the zone of bending
Trenches are common in the western Pacific, where there is ocean-ocean subduction
There is a long trench along the west coast of South America, where the Nazca Plate is being subducted under the continent
Volcanoes are common along mid-ocean ridges, where magma rises up from the asthenosphere to form new oceanic crust
They are common along subduction zones, where they form volcanic arcs
When the oceanic crust is first produced, at the mid-ocean ridges, a lot of water is combined with certain minerals in the igneous rocks
As the pressure and temperature increases down the subduction zone, this water is driven off, and it rises upward from the plate
The melting temperature of the mantle rock above the plate is lowered when water is added to it
This causes some of the mantle rock to melt.
Melting doesn’t start until the plate has reached a certain depth down the subduction zone, and then stops at a slightly deeper depth.
The “Ring of Fire” around the Pacific Ocean is caused by this melting at subduction zones all around the Pacific
Hot spots Originate at the boundary between the mantle and the outer core, are narrow plumes of unusually hot mantle material
These plumes rise up through the mantle and melt the rock at the base of the lithosphere, creating pools of magma
The magma then rises to the surface, resulting in hot spot volcanoes
http://www.wwnorton.com/college/geo/egeo/flash/2_10.swf
Locations of Some are located under continents
hot spots
Examples •Yellowstone
•Rift Valley of Africa (?)
•New Madrid fault (?)
In New Madrid, the largest series of earthquakes in the continental U.S. caused the Mississippi River to run backwards
Mountain ranges are mostly located near convergent plate boundaries
The combination of volcanoes at the surface and batholiths deep in the Earth adds a lot of new rock to the area above the subduction zone, and makes the elevation of the land much higher
Many subduction zones experience compression of two continents that collide
This causes masses of rock to be pushed together and stacked on top of one another, forming high mountains
http://highered.mcgraw-hill.com/sites/0072402466/student_view0/chapter19/animations_and_movies.html#
Growth of continents also grow as the continents igneous rock of volcanoes and
batholiths are added to the continent above the subduction zone
Continental the growth of the continent along
accretion its edges
This occurs during the long travels of an oceanic plate to a subduction zone
Hundreds of meters or more of oceanic sediment is deposited at the top of the plate
As the ocean plate collides with a continental plate, the sediment is scraped off and added to the edge of the continental plate
http://www.classzone.com/books/earth_science/terc/content/visualizations/es0808/es0808page01.cfm?chapter_no=visualization
Earthquakes are common along the mid-ocean ridges because of the movement along the transform faults that connect segments of the ridge crest
Earthquakes at subduction zones and continent-continent collision zones are a bigger problem for human society, because these areas are so common on the Earth, especially around the rim of the Pacific and along a belt that stretches from the Mediterranean to southeast Asia
Effects of Plate Tectonics
Check Your Understanding Date
Page G103 Page #
1. Why is plate tectonics
a suitable name for the
study of plate motion?
Explain.
2. What geographic
features would you
expect to see at plate
boundaries?
3. How do geoscientists
suggest that “hot spots”
are related to plate
tectonics?
4. In your own words
explain the process
of continental accretion.
Effects of Plate Tectonics
Understanding and Applying Date
Page G104 Page #
1a. Summarize where
most earthquakes are
located compared to
plate boundaries.
1b. Summarize where
most volcanoes are
located compared to
plate boundaries.
2a. Why are volcanoes
usually found on the
continental side of a
plate boundary?
2b. Why are earthquakes
usually found on the
continental side of a
plate boundary?
3. Write a paragraph
giving one idea you
think might explain how
at least some volcanoes
and earthquakes have
formed. Be sure to point
out examples by
describing their locations.
4. Make a list of the
various plate-tectonic
settings where mountain
ranges are likely to be
produced. For each item
on the list, draw a cross
section that shows the
mountain range and how
it relates to the plate-
tectonic setting. For
each item, give an
example from somewhere
in the world.
Effects of Plate Tectonics
Inquiring Further Date
Page G104 Page #
1. Plate tectonics and the
local climate
Research and report on
how your local region
has been affected
directly or indirectly by
plate tectonics.