Download Continental Drift and Plate

Earth Science-notes for chapter 10
In this unit, our objectives are:
-identifying that the lithosphere contains rocks and minerals and that minerals
make up rocks.
-describe how minerals and rocks are formed and classified
-describe the processes that contribute to the continuous changing of Earth’s
surface
 Earthquakes/volcanoes/volcanic eruptions/erosion/weathering/mountain
building/lithospheric plate movements
 Describe the interior structure of the Earth and Earth’s crust as tectonic
plates riding on top of slow moving currents of magma in the mantle
 Explain that most geological events result from PLATE MOTION!!
 Use models to analyze the size and shape of the Earth, its surface, and its
interior (globes/maps/satellite images)
 Explain that some processes in the rock cycle are directly related to
thermal energy and forces in the mantle that drive plate motion
 Explain that folding, faulting, and uplifting can rearrange rock layers so
that the youngest is not always on top
 Illustrate the three primary types of plate boundaries (transform,
divergent, and convergent) can cause different landforms (mountains,
volcanoes, and ocean trenches)
 Explain how landforms are created through a combination of destructive
(weathering and erosion) and constructive (crustal deformation, volcanic
eruptions, and deposition of sediment) forces
NOTES:
ROCKS:
Geologists must use ________________ observations to gather clues about
what Earth’s interior is made of and how it is structured.
This indirect evidence includes information learned by studying
_______________ and __________ that are exposed at Earth’s surface.
Waves are _______________ that carry energy through matter or space.
When an earthquake occurs, ____________ is carried through objects by
waves.
The ____________ of these waves depends on the density and nature of the
material they are traveling through.
 Certain ____________ are found in different places on Earth’s surface.
These rocks are made of material similar to what is thought to exist deep
inside Earth
The rocks formed far below the surface.
EARTH’S LAYERS:
Based on evidence from _________________________ and
______________________, scientists have produced a model of Earth’s
interior.
The model shows that Earth’s interior has at least four distinct layers—the
_________________, the ________________, the _________________, and the
_______________.
The innermost layer of Earth’s interior is the solid _________________. This
part of the core is dense and composed
At about 5,000°C, the inner core is the ______________ part of Earth.
Because of the weight of the surrounding rock, the core is under tremendous
_____________________.
Pressure increases because more material is pushing toward Earth’s center as
a result of ________________.
The inner core, at the center of Earth, experiences the greatest amount of
______________________..
What Influence does the Core have?
Because the core is so hot, it radiates a natural heat to the upper layers.
Because of this a current of heat comes into being. Those are also known as
the convection currents. The convection currents cause the movement of the
tectonic plates. This movement is called plate tectonics. The outer core and the
inner core together cause the earth's magnetism. Because the earth rotates,
the outer core spins, the inner core doesn't spin because it's solid. This gives a
kind of dynamo effect and causes the earth's magnetism. Magnetism has been
used by sailors to find their way on earth for thousands and thousands of
years. Magnetism also influences electro-particles outside the atmosphere of
the earth, up to more than 37,000 miles (60,000 km) into space.
 The __________________ __________ lies above the inner core and is
thought to be composed of mostly __________________ ______________.
 The outer core _____________ one type of wave and ____________ down
another. Because of this, scientists have concluded that the outer core is a
______________.
 The _________________ is the layer of Earth’s interior above the outer core,
and is the __________________ layer of the Earth’s interior. Even though it
is solid, the mantle __________________ slowly, similar to ______________.
 The mantle is divided into two parts:
o
o
 Earth’s outermost layer is the __________________. It is _______________
under the oceans and ____________________ through the continents. All
________________ on the Earth’s surface are part of the crust.
EARTH’S STRUCTURE
 __________________, _______________________, and
_______________________ are properties that are _________________ in
the crust and ________________________ in the inner core.
 The mantle is ______________ percent of the Earth’s mass.
 Draw and label the two graphs on page 291:
 The rigid, upper part of the Earth’s mantle and the crust is called the
__________________________. It is broken into about ________ sections or
_________________ that move around on the plastic-like _______________.
 The plates move _____________________. Have the plates always looked
like they do now? _______________________ What was North America
once connected to? _____________________________________________
 How much distance do plates move a year? __________________________
PLATE BOUNDARIES
 The places where the edges of different plates meet are called
_______________ ___________________________.
 Name three land features that boundaries form:
o
o
o
 __________________ are large fractures in rocks along which movement
occurs. They can cause ________________________.
PLATES THAT MOVE APART [DIVERGENT BOUNDARIES]
 Why do plates move apart?
_______________________________________________________________
_______________________________________________________________
 What is one important result of plates separating? _____________________
 Explain what happens when plates move apart:
_______________________________________________________________
_______________________________________________________________
 What are mid-ocean ridges?
_______________________________________________________________
_______________________________________________________________
 Separating/Divergent Plates:
 Sliding/Transform Plates:
 Colliding/Convergent Plates
 What are rift valleys and how are they formed?
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
PLATES THAT COLLIDE [CONVERGENT BOUNDARIES]
 When two plates move towards each other, they ____________________.
 The outcome depends on the _________________ of the two plates. Which
is more dense, oceanic crust or continental crust, and why?
_______________________________________________________________
_______________________________________________________________
 When rocks converge, it is called _____________________________. This
causes the layers to _______________ and _______________. What forms
when the layers are faulted and folded, they pile up and form ___________.
Which mountain is still rising because of plate collision? ________________
 When and oceanic plate collides with another oceanic or continental plate,
the more dense plate will ___________________ under the other.
 Continental-Continental Collision:
 Continental-Oceanic Collision:
 Oceanic-oceanic collision:
PLATES THAT SLIDE PAST [TRANSFORM BOUNDARIES]
 Plates can also __________ past each other. The boundaries where these
types of plates meet are called ________________ boundaries. When a
force pushes something in different directions, it is called _____________.
 Shearing causes ____________ to form and causes ___________________.
 Name a land feature in California that is a major fault: _________________
WHY DO PLATES MOVE?
 Earth’s plates are large, so to move something so massive it requires a lot of
_______________. Where does that energy come from? Reasons for plate
movement includes the following four possibilities:
o
o
o
o
Continental Drift and Plate-Tectonics Theory
Source: U.S. Dept. of the Interior, Geological Survey
According to the theory of continental drift, the world was made up of a single continent through most of geologic time. That continent
eventually separated and drifted apart, forming into the seven continents we have today. The first comprehensive theory of continental drift was
suggested by the German meteorologist Alfred Wegener in 1912. The hypothesis asserts that the continents consist of lighter rocks that rest on
heavier crustal material—similar to the manner in which icebergs float on water. Wegener contended that the relative positions of the continents
are not rigidly fixed but are slowly moving—at a rate of about one yard per century.
According to the generally accepted plate-tectonics theory, scientists believe that Earth's surface is broken into a number of shifting slabs or
plates, which average about 50 miles in thickness. These plates move relative to one another above a hotter, deeper, more mobile zone at average
rates as great as a few inches per year. Most of the world's active volcanoes are located along or near the boundaries between shifting plates and
are called plate-boundary volcanoes.
The peripheral areas of the Pacific Ocean Basin, containing the boundaries of several plates, are dotted with many active volcanoes that form the
so-called Ring of Fire. The Ring provides excellent examples of plate-boundary volcanoes, including Mount St. Helens.
However, some active volcanoes are not associated with plate boundaries, and many of these so-called intra-plate volcanoes form roughly linear
chains in the interior of some oceanic plates. The Hawaiian Islands provide perhaps the best example of an intra-plate volcanic chain, developed
by the northwest-moving Pacific plate passing over an inferred “hot spot” that initiates the magma-generation and volcano-formation process.
Plate-Tectonics Theory—The Lithosphere Plates of Earth
This figure shows the boundaries of lithosphere plates that are active at present. The double lines indicate zones of spreading from which
plates are moving apart. The lines with barbs show zones of underthrusting (subduction), where one plate is sliding beneath another. The
barbs on the lines indicate the overriding plate. The single line defines a strike-slip fault along which plates are sliding horizontally past one
another. The stippled areas indicate a part of a continent, exclusive of that along a plate boundary, which is undergoing active extensional,
compressional, or strike-slip faulting.
Source: U.S. Geological Survey.
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Continental Drift and Plate-Tectonics Theory — Infoplease.com
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Answer the following in your science notebook:
1. How are earthquake waves used to provide information about Earth’s
interior?
2. Give examples of where the three types of plate movement occur:
3. Describe the layer of Earth that is the largest.
4. List the layers of the Earth in order of DENSITY.
5. How can slab-pull and ridge-push contribute to the movement of a plate at
the same time?
6. List two possible reasons that plates move and explain the process behind
them.
7. What are rift valleys, what causes them, and where is one located?
8. What is plate subduction?
9. What is the asthenosphere?
10. Describe the theory of Continental Drift and state who first proposed the
theory.