Geology Chapter on Deformation and Faults
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Questions and Answers

______ refers to the changes in shape or position of a rock body in response to differential stress.

  • Stress
  • Compression
  • Deformation (correct)
  • Brittle failure

    • Which of the following is the best description for structural geology?

  • Study of sequences of sedimentary rocks and how their environments of deposition dictate how sediments are laid down
  • Study of rock deformation in response to tectonic forces (correct)
  • Study of earthquakes and how they move through Earth's interior
  • Study of intergrown mineral crystals in igneous rocks

    • How will compressional force change a rock body?

  • Shorten and thicken the rock. (correct)
  • Fracture the rock and grind the pieces alongside each other.
  • The rock will not change.
  • Stretch and thin the rock.

    • How will tensional force change a rock body?

    <p>Stretch and thin the rock.</p> Signup and view all the answers

    Which tectonic boundary is associated with compressional stress?

    <p>Convergent</p> Signup and view all the answers

    A rubber band being stretched in preparation to fire across the room is an example of what kind of deformation?

    <p>Elastic deformation</p> Signup and view all the answers

    Unbending a paper clip wire is an example of what kind of deformation?

    <p>Ductile deformation</p> Signup and view all the answers

    Which of the following is an example of brittle deformation?

    <p>Throwing a hammer through a glass windowpane</p> Signup and view all the answers

    Which of the following rocks would be more likely to experience brittle deformation rather than ductile deformation when subjected to stresses that exceed their strength?

    <p>Quartzite</p> Signup and view all the answers

    What is a fault?

    <p>A fracture in a rock along which motion has occurred</p> Signup and view all the answers

    Folds form in ________ temperature-________ pressure environments.

    <p>high-; high-</p> Signup and view all the answers

    Faults form in ________ temperature-________ pressure environments.

    <p>low-; high-</p> Signup and view all the answers

    A ___ is a circular fold where the youngest layers are in the middle and the oldest layers are on the outside.

    <p>Basin</p> Signup and view all the answers

    You are sitting in class when your professor begins talking about a dome with the inner layers dating back to the Tertiary and its outer layers dating back to the Permian. You immediately know this professor is wrong. What is your evidence?

    <p>Domes have the oldest layers in the middle, not the youngest.</p> Signup and view all the answers

    How many hinge lines does a monocline have?

    <p>Two</p> Signup and view all the answers

    What is the outcrop pattern of a plunging syncline?

    <p>The layers will open up in the direction of plunge.</p> Signup and view all the answers

    A(n) ________ fold has limbs that are tilted beyond the vertical to the point that the axial plane is horizontal, giving it the appearance of lying on its side.

    <p>Recumbent</p> Signup and view all the answers

    Which tectonic boundary would have many normal faults associated with it?

    <p>Divergent</p> Signup and view all the answers

    A ________ fault is created when the hanging wall moves up relative to the footwall.

    <p>Reverse</p> Signup and view all the answers

    What is the difference between a reverse fault and a thrust fault?

    <p>A thrust fault has a fault angle of less than 45°, whereas the angle of a reverse fault is greater.</p> Signup and view all the answers

    Which tectonic boundary would have many thrust faults associated with it?

    <p>Convergent</p> Signup and view all the answers

    Which of the following scenarios would best indicate that a thrust fault is present at a location?

    <p>Cambrian-aged rocks have been shoved on top of Jurassic-aged rocks.</p> Signup and view all the answers

    Faults that exhibit both dip-slip and strike-slip movement are called ________ faults.

    <p>Oblique-slip</p> Signup and view all the answers

    Mountain ranges such as the Appalachians and the Himalayas are examples of mountains that formed as a result of ________ faulting.

    <p>Thrust</p> Signup and view all the answers

    A ________ fault has a vertical fault plane and shows movement parallel to the orientation of the fault.

    <p>Strike-slip</p> Signup and view all the answers

    You are a seismologist and are driving out to a location where a fault has recently shifted. When you arrive at the location, you see that the road you are driving on was constructed across the fault line. Because of slippage along the fault, the road ahead has been shifted to the left by 20 feet. What kind of fault is present?

    <p>Left-lateral strike-slip</p> Signup and view all the answers

    Which type of fault was responsible for the devastation associated with the 1906 earthquake in San Francisco?

    <p>Transform</p> Signup and view all the answers

    Some of the most destructive earthquakes, such as the Haitian earthquake of 2010, occur along ________ faults.

    <p>Reverse</p> Signup and view all the answers

    What is the difference between faults and joints?

    <p>Joints form in place, whereas faults form because rock has moved.</p> Signup and view all the answers

    What are slickensides?

    <p>Polished and striated surfaces made on fault blocks</p> Signup and view all the answers

    Fault-block mountains are created due to ________ faults.

    <p>Normal</p> Signup and view all the answers

    Which of the following are examples of fault-block mountains?

    <p>Basin and Range</p> Signup and view all the answers

    ________ is the compass direction of the line produced by the intersection of an inclined rock layer with a horizontal plane.

    <p>Strike</p> Signup and view all the answers

    ________ is the angle of inclination of the surface of a rock unit measured from a horizontal plane.

    <p>Dip</p> Signup and view all the answers

    How will strike and dip marks be oriented on the geologic map of a nonplunging syncline?

    <p>Parallel strikes with dips pointing toward from the center of the fold</p> Signup and view all the answers

    Which of the following best describes the age relationship of the layers in an anticline?

    <p>Oldest on the outside of the fold, youngest on the inside</p> Signup and view all the answers

    Which of the following statements best describes the relationship between the topography of a region and the underlying structural geology?

    <p>Upfolds in the rock will make mountains and downfolds will make valleys.</p> Signup and view all the answers

    Detachment faults are low-angle ________ faults.

    <p>Normal</p> Signup and view all the answers

    How will rock salt likely respond when put under stress?

    <p>It will bend or flow</p> Signup and view all the answers

    How do joints form in tectonic environments?

    <p>Rocks near the surface are stretched and pulled apart.</p> Signup and view all the answers

    Movements along normal faults can produce alternating upthrown and down-dropped fault blocks. What are the names associated with these blocks, respectively?

    <p>Horsts and grabens</p> Signup and view all the answers

    Strained geologic materials lose their original configuration during deformation.

    <p>True</p> Signup and view all the answers

    Shear stress is a type of confining pressure.

    <p>False</p> Signup and view all the answers

    Rocks subjected to heat will be more likely to go through brittle deformation when stressed.

    <p>False</p> Signup and view all the answers

    Shearing produced fault zones in the deep crust and folding in the upper crust.

    <p>False</p> Signup and view all the answers

    A syncline is a downfold in rock where the youngest layers are in the middle of the fold and the youngest are on the outside.

    <p>True</p> Signup and view all the answers

    Some strike-slip faults are big enough to accommodate movement between two tectonic plates.

    <p>True</p> Signup and view all the answers

    Joints are fractures in a rock created by tension and will demonstrate significant displacement.

    <p>False</p> Signup and view all the answers

    Dip will always be 90° away from strike.

    <p>True</p> Signup and view all the answers

    ______ refers to the changes in shape or position of a rock body in response to differential stress.

    <p>Deformation</p> Signup and view all the answers

    Which of the following is the best description for structural geology?

    <p>Study of rock deformation in response to tectonic forces</p> Signup and view all the answers

    How will compressional force change a rock body?

    <p>Shorten and thicken the rock.</p> Signup and view all the answers

    How will tensional force change a rock body?

    <p>Stretch and thin the rock.</p> Signup and view all the answers

    Which tectonic boundary is associated with compressional stress?

    <p>Convergent</p> Signup and view all the answers

    A rubber band being stretched in preparation to fire across the room is an example of what kind of deformation?

    <p>Elastic deformation</p> Signup and view all the answers

    Unbending a paper clip wire is an example of what kind of deformation?

    <p>Ductile deformation</p> Signup and view all the answers

    Which of the following is an example of brittle deformation?

    <p>Throwing a hammer through a glass windowpane</p> Signup and view all the answers

    Which of the following rocks would be more likely to experience brittle deformation rather than ductile deformation when subjected to stresses that exceed their strength?

    <p>Quartzite</p> Signup and view all the answers

    What is a fault?

    <p>A fracture in a rock along which motion has occurred</p> Signup and view all the answers

    Folds form in ________ temperature-________ pressure environments.

    <p>high-; high-</p> Signup and view all the answers

    Faults form in ________ temperature-________ pressure environments.

    <p>low-; high-</p> Signup and view all the answers

    A ___ is a circular fold where the youngest layers are in the middle and the oldest layers are on the outside.

    <p>Basin</p> Signup and view all the answers

    You are sitting in class when your professor begins talking about a dome with the inner layers dating back to the Tertiary and its outer layers dating back to the Permian. You immediately know this professor is wrong. What is your evidence?

    <p>Domes have the oldest layers in the middle, not the youngest.</p> Signup and view all the answers

    How many hinge lines does a monocline have?

    <p>Two</p> Signup and view all the answers

    What is the outcrop pattern of a plunging syncline?

    <p>The layers will open up in the direction of plunge.</p> Signup and view all the answers

    A(n) ________ fold has limbs that are tilted beyond the vertical to the point that the axial plane is horizontal, giving it the appearance of lying on its side.

    <p>Recumbent</p> Signup and view all the answers

    Which tectonic boundary would have many normal faults associated with it?

    <p>Divergent</p> Signup and view all the answers

    A ________ fault is created when the hanging wall moves up relative to the footwall.

    <p>Reverse</p> Signup and view all the answers

    What is the difference between a reverse fault and a thrust fault?

    <p>A thrust fault has a fault angle of less than 45°, whereas the angle of a reverse fault is greater.</p> Signup and view all the answers

    Which tectonic boundary would have many thrust faults associated with it?

    <p>Convergent</p> Signup and view all the answers

    Which of the following scenarios would best indicate that a thrust fault is present at a location?

    <p>Cambrian-aged rocks have been shoved on top of Jurassic-aged rocks.</p> Signup and view all the answers

    Faults that exhibit both dip-slip and strike-slip movement are called ________ faults.

    <p>Oblique-slip</p> Signup and view all the answers

    Mountain ranges such as the Appalachians and the Himalayas are examples of mountains that formed as a result of ________ faulting.

    <p>Thrust</p> Signup and view all the answers

    A ________ fault has a vertical fault plane and shows movement parallel to the orientation of the fault.

    <p>Strike-slip</p> Signup and view all the answers

    You are a seismologist and are driving out to a location where a fault has recently shifted. When you arrive at the location, you see that the road you are driving on was constructed across the fault line. Because of slippage along the fault, the road ahead has been shifted to the left by 20 feet. What kind of fault is present?

    <p>Left-lateral strike-slip</p> Signup and view all the answers

    Which type of fault was responsible for the devastation associated with the 1906 earthquake in San Francisco?

    <p>Transform</p> Signup and view all the answers

    Some of the most destructive earthquakes, such as the Haitian earthquake of 2010, occur along ________ faults.

    <p>Reverse</p> Signup and view all the answers

    What is the difference between faults and joints?

    <p>Joints form in place, whereas faults form because rock has moved.</p> Signup and view all the answers

    What are slickensides?

    <p>Polished and striated surfaces made on fault blocks</p> Signup and view all the answers

    Fault-block mountains are created due to ________ faults.

    <p>Normal</p> Signup and view all the answers

    Which of the following are examples of fault-block mountains?

    <p>Basin and Range</p> Signup and view all the answers

    ________ is the compass direction of the line produced by the intersection of an inclined rock layer with a horizontal plane.

    <p>Strike</p> Signup and view all the answers

    ________ is the angle of inclination of the surface of a rock unit measured from a horizontal plane.

    <p>Dip</p> Signup and view all the answers

    How will strike and dip marks be oriented on the geologic map of a nonplunging syncline?

    <p>Parallel strikes with dips pointing toward from the center of the fold</p> Signup and view all the answers

    Which of the following best describes the age relationship of the layers in an anticline?

    <p>Oldest on the outside of the fold, youngest on the inside</p> Signup and view all the answers

    Which of the following statements best describes the relationship between the topography of a region and the underlying structural geology?

    <p>Upfolds in the rock will make mountains and downfolds will make valleys.</p> Signup and view all the answers

    Detachment faults are low-angle ________ faults.

    <p>Thrust</p> Signup and view all the answers

    How will rock salt likely respond when put under stress?

    <p>It will bend or flow</p> Signup and view all the answers

    How do joints form in tectonic environments?

    <p>Rocks near the surface are stretched and pulled apart.</p> Signup and view all the answers

    Movements along normal faults can produce alternating upthrown and down-dropped fault blocks. What are the names associated with these blocks, respectively?

    <p>Horsts and grabens</p> Signup and view all the answers

    Strained geologic materials lose their original configuration during deformation.

    <p>True</p> Signup and view all the answers

    Shear stress is a type of confining pressure.

    <p>False</p> Signup and view all the answers

    Rocks subjected to heat will be more likely to go through brittle deformation when stressed.

    <p>False</p> Signup and view all the answers

    Shearing produced fault zones in the deep crust and folding in the upper crust.

    <p>False</p> Signup and view all the answers

    A syncline is a downfold in rock where the youngest layers are in the middle of the fold and the youngest are on the outside.

    <p>True</p> Signup and view all the answers

    Some strike-slip faults are big enough to accommodate movement between two tectonic plates.

    <p>True</p> Signup and view all the answers

    Joints are fractures in a rock created by tension and will demonstrate significant displacement.

    <p>False</p> Signup and view all the answers

    Dip will always be 90° away from strike.

    <p>True</p> Signup and view all the answers

    Match the type of stress to the correct definition.

    <p>Forces move toward each other. = Compression Forces slide past each other. = Shear Forces pull apart from each other. = Tension</p> Signup and view all the answers

    Determine the type of stress necessary to produce each of the following geologic regions/features.

    <p>Basin and Range province = Tension San Andreas Fault = Shear Grand Teton Mountains = Tension Appalachian Mountains = Compression Dakota Hogback = Compression</p> Signup and view all the answers

    Match the type of rock deformation to its corresponding descriptions.

    <p>Rocks will change shape due to pressure but return to their original state when pressure is released. = Elastic deformation Rocks will shatter due to pressure. = Brittle deformation Rocks will change. = Ductile deformation</p> Signup and view all the answers

    Match the fault with the appropriate stress that caused it.

    <p>Normal fault = Tension Reverse fault = Compression Strike-slip fault = Shear</p> Signup and view all the answers

    Explain the role that confining pressure has on rock strength and how the rock deforms under pressure.

    <p>Confining pressure exerts equal pressure in all directions. As a result, the rocks are tightly compressed, which makes them stronger. When such rocks are subjected to stress, they will be more likely to bend rather than break.</p> Signup and view all the answers

    What are the four factors that influence rock strength? Describe how they will affect the rock when it is under stress.

    <p>Higher temperatures make the rocks softer and more able to stretch or become malleable rather than shatter. Confining pressure squeezes rocks, making them harder to break. Certain rock types are more ductile than others, and others are more brittle. For example, rocks with intergrown mineral crystals are more likely to shatter in response to stress, where rocks that are weakly cemented or have zones of weakness are more likely to bend. Finally, time also influences the rocks' response to stress. Stress applied over a long period of time is more likely to result in ductile deformation, while stress applied over a short period of time is more likely to result in brittle deformation.</p> Signup and view all the answers

    The Appalachian Mountains were formed when the North American continent collided with Africa to form the supercontinent Pangaea over 250 million years ago. What kind of tectonic boundary existed here? What sort of structural features would you expect to find in this region?

    <p>Since this is a convergent boundary, expected features would include folds such as anticlines and synclines as well as reverse or thrust faults.</p> Signup and view all the answers

    Although the Valley and Ridge province of the Appalachians is characterized by intensely folded rock, it is not the structures themselves that are resulting in the ridges and valleys. What rocks make up the Valley and Ridge province, which ones make each landform (ridges or valleys), and why?

    <p>The rocks of the Valley and Ridge province are largely sandstone, limestone, and shale. Differential weathering and erosion created the ridges and valleys. Ridges are made of sandstone and valleys of limestone and/or shale.</p> Signup and view all the answers

    Despite not seeing the severe tectonic forces of the Rocky Mountains, the interior states of Illinois and Michigan have basins (the Illinois and Michigan basins). However, these basins formed in a different way. Explain how the Illinois and Michigan basins formed without significant tectonic influence.

    <p>The Illinois and Michigan basins formed through subsidence. These basins were the repositories of large accumulations of sediment, the weight of which caused the crust to subside.</p> Signup and view all the answers

    Over the course of the last couple of centuries, major businesses all over the world have spent a great deal of time and money searching for and studying structural geologic features in order to find deposits of petroleum. How would these structures trap the substances these companies are interested in?

    <p>Oil companies are searching for or have searched for structural features such as domes, anticlines, and inclined faults. These features can act as petroleum traps. For example, petroleum will migrate along permeable rock layers in an anticline, making its way up the layer because it is less dense. Once the petroleum reaches the top of the fold, the overlying layer may act as an impermeable boundary, not allowing any further migration upward and trapping the product.</p> Signup and view all the answers

    The Basin and Range province is an extensional region in the American Southwest characterized by roughly parallel mountain ranges separated by broad, flat-bottomed valleys. What sort of structural features would you expect to find in this region?

    <p>Expected features would include normal faults, horsts, and grabens.</p> Signup and view all the answers

    Compare and contrast thrust faults and reverse faults.

    <p>Reverse and thrust faults are both the result of compressional stress. In both, the hanging wall moves up relative to the footwall. The main difference between these faults is that the fault plane of a thrust fault is much lower than that of a reverse fault, usually less than 30°. A thrust fault will also be responsible for significant crustal shortening, resulting in interesting situations where distant rocks are thrust on top of others, which not only shortens the crust but can result in violations of the law of superposition.</p> Signup and view all the answers

    Explain how stress is different from strain.

    <p>Stress is a measure of how much force is applied over a given area. Strain refers to the resulting change in the shape of the rock.</p> Signup and view all the answers

    Compare rock deformation in near surface environments to that deep within Earth's crust. Which deformation style will be more common in each location?

    <p>Brittle deformation is more common near the surface. Ductile deformation is more common at depth.</p> Signup and view all the answers

    Explain the difference in orientation between a nonplunging anticline and a plunging anticline.

    <p>A nonplunging anticline has a symmetrical shape with horizontal beds while a plunging anticline narrows as you move along the fold axis.</p> Signup and view all the answers

    Study Notes

    Deformation Flashcards Overview

    • Deformation involves changes in shape or position of rock due to differential stress.
    • Structural geology studies rock deformation in response to tectonic forces.

    Forces and Their Effects on Rock

    • Compressional Force: Shortens and thickens rocks.
    • Tensional Force: Stretches and thins rocks.

    Tectonic Boundaries

    • Convergent Boundaries: Associated with compressional stress.
    • Divergent Boundaries: Associated with tensional stress which leads to normal faults.
    • Transform Boundaries: Associated with strike-slip faults.

    Types of Deformation

    • Elastic Deformation: Rocks return to original shape when pressure is released (e.g., stretching a rubber band).
    • Ductile Deformation: Rocks bend under pressure but do not break (e.g., unbending a paper clip).
    • Brittle Deformation: Rocks shatter under stress (e.g., breaking glass).

    Fault Types

    • Fault: A fracture in rocks where motion has occurred.
    • Normal Fault: Hanging wall moves down relative to footwall, typically formed under tensional stress.
    • Reverse Fault: Hanging wall moves up, formed under compressional stress.
    • Thrust Fault: Type of reverse fault with a low-angle fault plane.
    • Strike-Slip Fault: Movement is horizontal, can be left-lateral or right-lateral.

    Geological Features

    • Folds: Result from compressional forces; anticlines have oldest layers on the outside, synclines have youngest in the middle.
    • Mountains: Formed by thrust and reverse faulting, such as the Himalayas and Appalachians.
    • Fault-Block Mountains: Formed due to normal faults; examples include the Basin and Range.

    Rock Strength Influencing Factors

    • Temperature: Higher temperatures lead to softer, more malleable rocks.
    • Confining Pressure: Increases strength; rocks are more resistant to breaking.
    • Rock Type: Ductility varies; intergrown minerals are brittle, weaker cemented rocks are ductile.
    • Time: Long-term stress can cause ductile deformation; short-term stress often results in brittle deformation.

    Key Geological Terms

    • Slickensides: Polished surfaces on fault blocks due to movement along faults.
    • Joints: Fractures that do not show significant displacement.
    • Horsts and Grabens: Terms associated with alternating fault blocks due to normal faulting.

    Relationship Between Topography and Geology

    • Upfolds create mountains, downfolds create valleys.
    • Structural features like domes and basins trap petroleum, influencing geological resource exploration.

    Stress vs. Strain

    • Stress: Force applied over an area.
    • Strain: The resulting change in shape due to applied stress.

    Anticlines vs. Synclines

    • Anticline: Oldest layers are at the outer edges, with younger layers inside.
    • Syncline: Youngest layers at the center and oldest on the outside.

    Deformation Styles in Different Environments

    • Brittle deformation is more common near the Earth's surface; ductile deformation is predominant deep within the crust.

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    Explore the fascinating concepts of rock deformation and fault types in this quiz. Understand how different forces affect rocks and the implications of tectonic boundaries on geological structures. Test your knowledge on elastic, ductile, and brittle deformations through structured questions.

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