Name: ________________________________
Date: ________________________________
Chapter 11: Deformation of the Crust
Section 1: How Rock Deforms
Isostasy
•
Deformation - the bending, ______________________________, and breaking of Earth’s crust;
the change in the shape of rock in response to stress.
•
Deformation can occur when the weight of some part of Earth’s _________________ changes.
•
When the lithosphere thickens and becomes heavier, it sinks deeper into the
______________________________.
•
When the ______________________ thins and becomes lighter, it rises higher in the
asthenosphere.
•
The force due to gravity presses the lithosphere down on the asthenosphere. The buoyant force
of the asthenosphere _____________________________ on the lithosphere.
•
Isostasy - a condition of _____________________________ and buoyant equilibrium between
Earth’s lithosphere and asthenosphere.
•
When the weight of the lithosphere changes, the lithosphere sinks or rises until a balance is
reached once again. The movements of the lithosphere to reach isostasy are called
___________________________________________.
•
The diagram below shows isostatic adjustments as a result of ___________________________.
Mountains and Isostasy
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In mountainous regions, isostatic adjustments _____________________________ occur.
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The rock that forms mountains is worn away by the erosive actions of ____________________,
_________________________, and ice.
Name: ________________________________
Date: ________________________________
•
This erosion can significantly reduce the ___________________ and ___________________ of a
mountain range.
•
As a mountain becomes smaller and lighter, the area may rise by isostatic adjustment in process
called _______________________________.
Deposition and Isostasy
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Isostatic adjustments occur in areas where rivers carrying large amounts of
__________________, _______________________, and gravel flow into larger bodies of water.
•
When a river flows into an ocean, most of the material that the river carries is
_____________________________ on the nearby ocean floor.
•
The added weight of the deposited material causes the ocean floor to sink by isostatic
adjustment in a process called ____________________________________.
Glaciers and Isostasy
•
Isostatic adjustments also occur as a result of the growth and retreat of glaciers and
__________________________________________.
•
The weight of the ice causes the lithosphere to __________________, while the ocean floor
____________________________ because the weight of the overlying water is less.
•
When glaciers or ice sheets _________________, the land rises and the ocean floor sinks.
Stress
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As Earth’s lithosphere moves, the rock in the crust is ______________________, stretched, and
____________________________. These actions exert force on the rock called stress.
•
Stress - the amount of force per unit area that acts on a ______________________.
•
Stress also occurs in Earth’s crust when tectonic plates collide, separate, or
_____________________________ past each other.
•
There are three types of stress: compression, _____________________, and shear stress.
Compression
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Compression is the type of stress that squeezes and _________________________________,
such as rock.
•
Compression can _________________________ the amount of space that rock occupies.
•
More commonly, however, compression changes the shape of rock while pushing it
_____________________________ or deeper down into the crust.
Compression occurs ___________________________________ convergent boundaries.
Tension
•
Tension is stress that ______________________ and __________________ a body apart.
Name: ________________________________

Date: ________________________________
•
When rock is pulled apart by tension, it tends to become ___________________________.
•
Tension occurs at or near _________________________________ boundaries.
Which two kinds of stress pull rock apart?
Strain
•
Strain - any change in a rock’s _______________________________________ caused by stress.
•
When stress is applied _________________________, the deformed rock may regain its original
shape when the stress is removed.
•
The amount of stress that rock can withstand without _________________________ changing
shape is ________________________________.
•
If a stress ________________________ the rock’s limit, the rock’s shape permanently changes.
Types of Permanent Strain
•
__________________ strain and _________________ strain are types of permanent strain.
•
Materials that respond to stress by breaking or fracturing are brittle. Brittle strain appears as
___________________________ or ___________________________.
•
Ductile materials respond to stress by __________________ or deforming without breaking.
Ductile strain is a change in the __________________________________________ of rock in
which the rock does not crack or fracture.
Factors that Affect Strain
•
The composition of rock determines where rock is ductile or brittle.
•
Temperature and ________________________________ also affect how rock deforms.
•
At ________________________ temperature and pressure, rock is likely deform in a
___________________________ way.
•
At ___________________ temperature and pressure, rock will deform in a
________________________ way.
Name: ________________________________
Date: ________________________________
•
The amount and type of stress and the _____________________ at which stress is applied
affects strain.
•
The _____________________ the stress on the rock is, the more likely rock is to undergo brittle
strain.
•
The more ___________________ stress is applied to rock, the more likely rock is to respond in a
brittle way.
Folds
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When rock deforms in a ductile way, ___________________________ commonly form.
•
Fold - a form of ductile strain in which rock layers _____________________, usually as a result
of compression.
•
A fold is most easily observed where flat layers of rock were compressed or squeezed
_________________________.
•
Although a fold commonly results from ____________________________, it can also from as a
result of _____________________________ stress.
Anatomy of a Fold
•
Scientists use several features of folds to identify and describe the folds.
•
The sloping sides of a fold are called ____________________________.
•
The limbs meet at the bend in the rock layers, which is called the _______________________.
•
If both halves of a fold are ____________________________, then the fold has an axial plane.
The axial plane is a place that could _________________ the fold into two symmetrical halves.
•
If a fold is ____________________________________, it appears to be lying on its side.
•
Name two features of a fold.
_______________________
_______________________
Types of Folds
•
To categorize a fold, scientists study the _____________________ ages of the rocks in the fold.
•
An anticline is a fold in which the ______________________ is in the center of the fold.
Anticlines are commonly ___________________ shaped.
•
A syncline is a fold in which the _________________________ is in the center of the fold.
Synclines are commonly ____________________ shaped.
Name: ________________________________
•
Date: ________________________________
A monocline is a fold in which both limbs are ______________________ or almost horizontal.
Monoclines form when one part of Earth’s crust moves _______________________________
relative to another part.
Sizes of Folds
•
Folds vary greatly in size. Some folds are small enough to be contained in a
__________________________ rock specimen. Other folds cover thousands of square
kilometers can be seen only from the ________________.
•
A large anticline may form a _______________________, which is a large, narrow strip of
________________________ land that can occur near mountains.
•
A large syncline may form a _______________________.
Faults
•
Near the Earth’s surface, where temperatures and pressures are ______________________,
stresses on rock can cause rock to break.
•
Breaks in rock along which there is no movement of the surrounding rock is called a
__________________________.
•
A break along which the surrounding rock moves is called a ___________________________.
•
Fault - a break in a body of rock along which one block _______________________ relative to
another; a form of brittle strain.
•
The surface or plane along which the motion occurs is called the _________________________.
•
In a nonvertical fault, the ______________________________ is the rock above the fault plane.
•
The _______________________________ is the rock below the fault plane.
Normal Faults
•
A normal fault is a fault in which the hanging wall moves _______________________________
relative to the footwall.
Name: ________________________________
Date: ________________________________
•
Normal faults commonly form at _________________________ boundaries, where the crust is
being pulled apart by tension.
•
Normal faults may occur as a series of parallel fault lines,
forming steep, _________________________ landforms.
Reverse Faults
•
When compression causes the hanging wall to move
upward relative to the footwall,
a _________________________________ fault forms.
•
A thrust fault is a special type of reverse fault in which the fault plane is at a low angle or is
nearly ______________________________.
•
Reverse faults and thrust faults are common in steep mountain ranges, such as the
__________________________ and ___________________________.

How does a thrust fault differ from a reverse fault?
Name: ________________________________
Date: ________________________________
Strike-Slip Faults
•
In a strike-slip fault, the rock on either side of the fault plane slides horizontally in response to
____________________________stress.
•
Strike-slip faults got their name because they slide, or __________________, parallel to the
direction of the length, or strike, of the fault.
•
Strike-slip faults commonly occur at ________________________ boundaries. They also occur
at fracture zones between offset segments of mid-ocean ridges.
•
Commonly, strike-slip faults occur as ____________________ of smaller faults in areas where
large-scale deformation is happening.
Sizes of Faults
•
Like folds, faults vary greatly in __________________. Some faults are so small that they affect
only a few layers of rock in a small region.
•
Other faults are __________________________ of kilometers long and may extend several
kilometers _________________Earth’s surface.
•
Large faults that cover thousands of kilometers are composed of systems of many smaller,
related faults.
San Andreas Fault (California)
Great Glen Fault (Scotland)