Questions and Answers
A circular dome structure is most likely to be found at which kind of location?
What does a geologic cross-section show?
A vertical slice cut through a part of the crust.
What does a region of folds cut by normal faults indicate?
Compression followed by tension.
Where are extremely large earthquakes likely to take place?
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In a location experiencing tensional tectonics, where would you expect faults to have larger dip angles?
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In a symmetrical syncline fold structure, the limbs of the fold dip:
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Rocks _____________ under tensional forces than under compressive forces.
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Study of the San Andreas fault suggests that cataclastic textures are present __________, and mylonites form _______________.
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What are tectonic forces that deform rocks primarily?
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What is the angle at which a sedimentary bed is inclined from horizontal called?
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What is the modification of rocks by squeezing, stretching, folding, and faulting called?
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What type of forces dominate at transform plate margins?
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Over what period commonly happens the series of tectonic events producing a mountain range?
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What type of structure is a basin?
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When did the rift valleys found in the Basin and Range province form?
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Where can you find an example of a cross-section in nature?
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What type of fault is the San Andreas fault in general?
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Which of the following is an example of a fold belt?
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What can a geologist learn by measuring the orientation of faults and fold structures?
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Which of the following types of deformation are observed along the San Andreas fault?
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Igneous and metamorphic rocks in the crystalline basement tend to be ___________________ whereas overlying sedimentary rocks are commonly _________________.
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Study Notes
Circular Dome Structures
- Circular dome structures are primarily found in continental interiors.
Geologic Cross-Section
- A geologic cross-section represents a vertical slice through the Earth's crust, illustrating subsurface structures.
Folds and Faults
- A region displaying folds intersected by normal faults indicates initial compression followed by subsequent tension in geological processes.
Megathrust Faults
- Extremely large earthquakes occur on megathrust faults, typically located at continent-ocean convergent boundaries.
Tensional Tectonics
- In locations experiencing tensional tectonics, faults tend to have larger dip angles in the shallow crust compared to the deeper crust.
Symmetrical Syncline
- In a symmetrical syncline fold structure, the limbs dip toward each other, creating a "U" shape.
Rock Breaking Under Forces
- Rocks are more prone to breakage under tensional forces than under compressive forces.
Cataclastic Textures and Mylonites
- Research on the San Andreas fault indicates that cataclastic textures are found above 20 km depth, while mylonites form below this depth.
Tectonic Forces
- The primary tectonic forces responsible for rock deformation are predominantly horizontally directed.
Sedimentary Bed Inclination
- The term "dip" refers to the angle at which a sedimentary bed is inclined from the horizontal.
Deformation of Rocks
- Deformation encompasses the modification of rocks through processes such as squeezing, stretching, folding, and faulting.
Transform Plate Margins
- Shearing forces dominate at transform plate margins, leading to lateral movements of crustal blocks.
Mountain Range Formation
- The tectonic events that lead to the formation of mountain ranges typically occur over several tens of millions of years.
Basin Structure
- A basin is classified as a syncline where all sedimentary beds incline toward the center of a depression.
Rift Valleys
- The rift valleys found in the Basin and Range province formed within the last 15 million years.
Natural Cross Sections
- Natural examples of cross-sections can be observed in vertical rock walls, such as those in quarries.
San Andreas Fault Nature
- The San Andreas fault is identified as a right-lateral strike-slip fault.
Fold Belts
- The Valley and Ridge Belt of the Appalachians serves as a classic example of a fold belt.
Geological Analysis
- By measuring the orientation of faults and fold structures, geologists can infer the directions of the forces that led to folding and faulting.
Deformation Types at San Andreas
- Deformation observed along the San Andreas fault includes strike-slip faulting, reverse faulting, and instances of rifting and volcanic activity.
Crystalline Basement Rocks
- Igneous and metamorphic rocks in the crystalline basement are typically hard and brittle, whereas overlying sedimentary rocks are often soft and ductile.
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Description
Test your knowledge on key concepts from Chapter 7 of geology. This quiz covers topics such as structural geology, seismic activity, and the geological features of continental interiors. Perfect for students looking to reinforce their learning or prepare for exams.
