Download Theory of Plate Tectonics

Plate Tectonics
Test Review
1) What is the Theory of Plate Tectonics?
The Earth’s crust is divided into
sections (plates) that float
on the mantle and move due to
convection currents in the mantle.
2) For Each of the landforms below, draw a
diagram and show how it is formed by the
movements of tectonic plates.
mountains & deep ocean trenches:.
2) For Each of the landforms below, draw a
diagram and show how it is formed by the
movements of tectonic plates.
Mid-ocean ridge & rift valley
3) What evidence did scientists use to
understand that Earth is broken into plates?
The evidences began with Wegener’s
Theory of Continental Drift. Ultimately,
It is the volcanoes and the origins of
Earthquakes that created a dot-to-dot
the really allows us to draw plate
boundaries.
4) What is the force that drives the movement
of the tectonic plates?
Convection currents in the mantle.
5) Describe the steps in history leading to the
development of Plate Tectonic Theory?
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Noted similar fossils on separate continents
Wegener’s Theory of Continental Drift (early 1900’s)
Development of Sonar (1940’s)
Discovery of Mid-Ocean Ridge
Noted that the seafloor was older further from the center
Theory of Sea Floor Spreading
Patterns of Earthquakes & Volcanoes (dot to dot)
Theory of Plate Tectonics (1960’s)
6) What is the Theory of Continental Drift?
Alfred Wegner stated that at one time,
the continents were joined as a single
super-continent, which he named
Pangaea. The continents have slowly
drifted apart since then.
6, cont’d) What is the Theory of Continental Drift?
• Continents appear to fit together like a
jigsaw puzzle.
• Distribution of fossil remains over several
continents.
• Similar rock layers on different
continents.
• Glacial marks on different continents
appear to line when the continents are
moved together.
8) Explain Sea Floor Spreading
Sea Floor Spreading is the eruption of
volcanoes at the mid-ocean ridge forming
new crust and pushing outward from there
so that the older crust is found at the
edges of the plates.
the movement of the sea floor is caused by
the convection currents in Earth’s mantle.
Sonar was a key technology that led to
the idea of Sea Floor Spreading.
9) Sketch a diagram to show Sea floor Spreading.
areas of oldest curst
10) Explain subduction.
Hint: root – sub – to go under
Subduction occurs when a more dense
Plate moves under a less dense plate. At
The boundary, this forms a deep trench.
Further back from the boundary, you
would expect volcanoes on land or
volcanic islands in the ocean.
11) Explain weathering.
Weathering is the breaking down of rock
by physical and chemical means.
11)
(CONT’D)...
11) (cont’d) Explain erosion.
Erosion is the movement of weathered
material cause by wind, water, glacier,
and gravity
12) The puzzle-like fit of the continents is one of the
evidences given to explain continental drift (yes,
this should be one of your answers for #6!), but
the continents don’t fit together perfectly. Why?
Over the millions of years that the
continents have been moving apart, they
have been undergoing the natural
weathering forces. This weathering and
erosion has begun to alter the continents
from their original shapes.
13) Explain how weathering and erosion effect Earth’s
surface.
Weathering and erosion generally level
things out. Mountains are worn down
and valleys are filled up. Sometimes,
water does carve deep scars into earth
as well.
14) Define the following terms: Topographic Map,
Contour Line, Contour Interval, Hachure Marks
and Index Contour.
Topographic Map: a map showing the
elevation of the land.
Contour Line: a line on a topographic
map that connects points of equal
elevation
Contour Interval: the “step up” or
elevation change between two contour
lines.
14) (cont’d) Define the following terms: Topographic
Map, Contour Line, Contour Interval, Hachure
Marks and Index Contour.
Hachure Marks: little “tic” marks on a
contour line showing that it going down
to a depression..
Index Contour: a special contour line on
a topographic map that is labeled with
the elevation (and is often dark/bold)
15) What is the contour interval for the map above?
20
16) Draw a topographic map that shows a steep incline.
Steep slope
(lines close together)
200
150
17) Draw a topographic map that shows a gentle incline.
Gentle slope
(lines far apart)
200
150
18) What direction is Mill River Flowing?
Northwest (note the contour
line “V” points upstream)
19) What is the highest elevation on the map?
380 meters (+)
20) What is the elevation of point Z?
220 meters
THE FOLLOWING SLIDES ARE ANSWERS
TO TEST REVIEWS WE USED IN THE
PAST. MUCH OF THE MATERIAL IS THE
SAME, JUST RE-WORDED. IT MAY BE
WORTH LOOKING AT AS YOU PREPARE
FOR THIS YEAR’S TEST!
4) How do we know where the plate
boundaries are?
Volcanoes and the origins of earthquakes
create a dot-to-dot the really allows
us to draw plate boundaries.
1)
What were Wegner’s four “evidences” of Continental Drift
(and give a short explanation of what each means)?
• Continents appear to fit together like a
jigsaw puzzle.
• Distribution of fossil remains over several
continents.
• Similar rock layers on different
continents.
• Glacial marks on different continents
appear to line when the continents are
moved together.
2)
There are three “plate movements” that can
occur (toward each other, apart, and sliding
past). Name them. Draw a sketch of each. Show
what geologic features occur at each
• Convergent
Folded Mountains, Volcanic Islands, deep sea trenches
• Divergent
Mid ocean ridge, rift valley
• Transform
Faults
3)
Explain sea-floor spreading (and diagram it).
What is it used as “evidence” for?
• Sea floor spreading is evidence for plate
tectonics
4)
Explain the relationship between the location of
volcanoes/earthquakes and plate tectonics.
• Most volcanoes and earthquakes occur
along plate boundaries
• this is the “dot to dot!”
5)
The earth is a constant sized sphere…However,
as plates move around, crust is constantly being
created and destroyed. Explain this idea (be sure
to note which types of plate boundaries are
involved).
• New crustal material is formed at divergent
boundaries and older crustal material
subducts back into the mantle at
convergent boundaries
6)
What causes the gigantic tectonic plates move?
Diagram it and be sure to include at least two
plates moving toward each other and two moving
away from each other.
• Convection currents in earths mantle
cause tectonic plates to move.
7)
Diagram how hot-spot volcanoes are used to
determine the direction of plate movement.
8) Diagram sonar and explain how it works.
• Sound wave are sent to the ocean floor
and reflect back to the source. The shape
of the ocean floor determines how the
sound waves are received reveling the
contour of the ocean floor.
9) What causes folded mountains?
• Two continental plate colliding cause
folded mountains. Continental plates have
approximately the same density and do
not subduct.
10)
What determines if a plate will slide under
another?
• Denser crustal material tends to
subduct or slide under a less dense
crustal material.
11)
Draw the three types of convergent boundaries.
Explain the plate movement and label the crustal
features.
• Two plate are moving toward one another
12) Draw a divergent boundary. Explain the plate
movement and label the crustal features.
• Two ocean plates are moving away form
one another.
13)
What type of plate movement causes mostly
earthquakes (and not much else)?
• Two plates sliding past one another at a
transform boundary.
14)
What type of plate movement is happening in
California?
• Two plates are sliding past one another.
15)
What type of plate movement is happening in the
Himilayas (between India and the rest of Asia)?
• Two continental plates are moving toward
each other forming the Himalayan
mountains (folded mountains)
16)
What type of plate movement is happening in the
middle of the Atlantic Ocean?
• The ocean plates are moving away from
each other at the Mid Atlantic Ridge.
20)
What is land subsidence and give at least one
cause of land subsidence.
• When the land surface sinks.
• Human and geologic activity cause land
subsidence
• Mid ocean ridge is a place where land
subsidence occurs
3) Compare/contrast compression and tension
forces..
Compression: to push together. This
would be a convergent plate boundary
Tension: to pull apart. This would be
a divergent plate boundary.