Download Geography 12

Chapter 6 Objectives:
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Geography 12
Worksheet 6.6
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Plate Interiors: Zones of Inactivity
Read pages 111 – 114 of Planet Earth: A Physical Geography. Answer
the following questions:
Vocabulary (1 mark each)
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Cratons:
The most stable part of a continent, often made up of ancient rocks, that experiences
few earthquakes or volcanic eruptions; often know as shields
Accretion:
The process of growth through accumulation; often used to refer to the growth of the
planets through the gravitational attraction of plantesimals, asteroids, and meteoroids:
the growth of continents or cratons by the addition of new rocks along their edges
through mountain-building activity or collisions with other blocks of continental crust.
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Supercontinent:
A single, massive continent made up of all the world’s continents; Pangea is the last
supercontinent that began to break up about 100 million years ago to form the smaller,
more numerous continents we know today
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Appreciate the power and
scope of tectonic processes
and their effects
Appreciate the slowness of
tectonic processes based on
a human time scale
Understand that the
lithosphere is an everchanging part of a dynamic
planet
Understand the general
pattern of tectonic activity
over geologic time and
explain the location pattern
of tectonic activity over the
earth’s surface
Explain the tectonic
processes that shape the
earth’s surface, including
folding, faulting, and
volcanic activity
Describe and explain the
pattern of major surface
features created by
tectonic processes
Predict the nature and
general patterns of
occurrence of tectonic
activities and processes,
especially earthquakes and
volcanic eruptions
Describe the positive and
negative aspects of tectonic
activities
Short Answer (2 marks each)
1. Scientists speculate ocean floor rock is much younger that continental rocks. Why
would ocean floor rocks be younger?
Because of the subduction. The rocks at subduction zones are consumed as they migrate to the
ansthenosphere. Continental rocks on the other hand are lighter and are not consumed at subduction
zones, allowing them to stick around much longer.
2. Cratons are described as the roots of mountains. Explain.
They are actually what is left from millions of years of erosion, so they are called the roots of the
mountains.
3. Briefly describe the process of accretion.
The edges of continents are often plate boundaries and are active zones of mountain building. This is
one way continents increase in size.
Another way they increase in size is through erosion of the mountains, depositing eroded material at the
edge of the continent.
4. How did Wegener explain his idea of a supercontinent splitting up and the pieces
(continents) moving apart from each other?
He looked at the shape of the continents and concluded that because they look like the fit together they
must have drifted apart. Later, scientists theorized thatThe supercontinent acted as a thermal cap,
allowing thermal activity to increase under the supercontinent. This caused hills which allowed the
continents to split and slide away from each other.
5. Using an outline map of the present world, reassemble the continent of Pangea.
Color each continent and then cut and paste them into Pangea. (5 marks for neatness,
5 for accuracy)