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Our Dynamic Earth Unit Review Sheet
Directions: Use your notes and
BOTH texts to fill in this review sheet. Keep it and study it and do
not turn it in to me until the day you are ready to take your test.
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1. |
The Earth’s lithosphere is made up
of
 large and
small plates that move
about over it. Most of our continent is on the
plate, except the western
edge of California south of San Francisco) and Hawaii,
which are on the
plate. |
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2. |
The movement of the plates is
caused by
currents in the
mantle. As heated material expands and rises, the plates
move apart, called
boundaries, especially at mid–ocean ridges, pushing
continents farther apart. As the plates crash into each
other, called
boundaries,
they are forced back down into the mantle. At these
boundaries, if both plates are
continental, mountain chains form (by uplift,) like the
in Asia and the
Mountains here in the U.S. If an oceanic
plate is forced under a continental plate, it is called
a
boundary or zone. |
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3. |
first proposed the theory of
continental drift. He based his theory on several pieces
of compelling evidence: first of all, Africa and South
America look like they fit together, like the pieces of
a
. Fossil remains of
, a small reptile 270 million
years ago (that couldn’t swim the Atlantic or fly) are
found in beds along the coast thousands of miles apart.
There were also several mountain chains and beds of coal,
precious metals and gems that seemed to have been ripped
apart as the continents separated. We also have coal
beds and salt deposits (that form in tropical climates)
in temperate Germany and the U.S. now, and glacial
deposits (that formed in polar regions) in southern
Africa and South America, proving movement. Most compelling
of all is the evidence of
reversal found in the rocks of the
ocean floor, proving that the rocks nearest the
mid–ocean ridges are young, and the farther away you get
from them, the older the rocks get. |
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4. |
Molten rock underground is called
, and on the surface it is called
. Continental volcanoes usually have
cooler (< 1000°,) more viscous,
light weight and light
colored
lava, and oceanic
volcanoes usually have lava that is hotter (up to
2000°), thinner, more fluid, dark colored and denser
lava. |
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5. |
Most of the active volcanoes and
earthquake zones of the world are around the rim of the
Ocean, called the
of
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form when magma cools off and hardens underground. The
largest are the
, which
can extend under several states, and form the cores of
many mountain ranges.
are smaller versions, less than 100 km2.
cut vertically through rock layers,
flow between them, and if they get thick enough to bulge
up the land above them, they are called
,
which formed the Henry Mountains. Of Utah and the Black Hills
of South Dakota. An extinct volcano may erode away,
exposing a
(the cooled
core), which can be full of the largest precious gems,
like the one that formed the great Kimberly mines of
South Africa.
in Hawaii and
in the Pacific
Northwest of the continental U.S. are two active
volcanoes. |
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6. |
The
of the earthquake is underground on the fault. The
is the point on the surface (above it) where most of the
damage occurs. Earthquakes generate
waves, the first to arrive at a seismograph are the
waves, and the second to arrive are the
waves, which cannot go through a liquid (like the outer
core of the earth, so are not always received.) the last
to arrive are the
waves, which are limited to travel in the crust and do
most of the damage. The time lag between the arrival of
the first two waves gives us the
to the epicenter, and if we use information from
different seismic stations, we can pinpoint the exact
location of it. Evaluate the risk of earthquakes in both
California and here in Missouri: |
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