Podcast
Questions and Answers
What distinguishes joints from faults in geological terms?
What distinguishes joints from faults in geological terms?
Which of the following is true regarding the formation of joints?
Which of the following is true regarding the formation of joints?
What is a key characteristic of faults?
What is a key characteristic of faults?
Which statement accurately describes the causes of joints?
Which statement accurately describes the causes of joints?
Signup and view all the answers
In which context are joints particularly common?
In which context are joints particularly common?
Signup and view all the answers
What is the term for the direction of intersection of a rock layer with a horizontal surface?
What is the term for the direction of intersection of a rock layer with a horizontal surface?
Signup and view all the answers
Which force category is associated with reverse faulting as a brittle outcome?
Which force category is associated with reverse faulting as a brittle outcome?
Signup and view all the answers
What is a geological cross section primarily used to depict?
What is a geological cross section primarily used to depict?
Signup and view all the answers
What is the angle at which a rock bed inclines from the horizontal called?
What is the angle at which a rock bed inclines from the horizontal called?
Signup and view all the answers
What defines the orientation of a fault plane?
What defines the orientation of a fault plane?
Signup and view all the answers
In geological blocks, which view can help visualize rock volumes in 3D?
In geological blocks, which view can help visualize rock volumes in 3D?
Signup and view all the answers
What kind of forces cause crustal thinning as a ductile outcome?
What kind of forces cause crustal thinning as a ductile outcome?
Signup and view all the answers
What type of fault occurs when the hanging wall block moves down relative to the foot wall block?
What type of fault occurs when the hanging wall block moves down relative to the foot wall block?
Signup and view all the answers
What type of faulting results from shearing forces?
What type of faulting results from shearing forces?
Signup and view all the answers
What kind of forces typically cause the formation of faults?
What kind of forces typically cause the formation of faults?
Signup and view all the answers
Which type of fault is indicative of tectonic compression?
Which type of fault is indicative of tectonic compression?
Signup and view all the answers
Which of the following is NOT a factor that influences how rocks bend or break?
Which of the following is NOT a factor that influences how rocks bend or break?
Signup and view all the answers
Where are faults commonly found?
Where are faults commonly found?
Signup and view all the answers
What does a geological map provide information about?
What does a geological map provide information about?
Signup and view all the answers
What is the expected ductile outcome of compressive forces acting on rocks?
What is the expected ductile outcome of compressive forces acting on rocks?
Signup and view all the answers
Under what conditions are rocks more likely to exhibit a ductile response?
Under what conditions are rocks more likely to exhibit a ductile response?
Signup and view all the answers
What type of forces dominate at divergent boundaries?
What type of forces dominate at divergent boundaries?
Signup and view all the answers
Which type of rocks typically exhibit a brittler response at shallow depths?
Which type of rocks typically exhibit a brittler response at shallow depths?
Signup and view all the answers
What is the primary characteristic of brittle outcomes in rocks?
What is the primary characteristic of brittle outcomes in rocks?
Signup and view all the answers
Which statement about the strength of igneous rocks relative to sedimentary rocks is generally true?
Which statement about the strength of igneous rocks relative to sedimentary rocks is generally true?
Signup and view all the answers
What occurs under conditions of low temperature and confining pressure in rocks?
What occurs under conditions of low temperature and confining pressure in rocks?
Signup and view all the answers
What type of geological forces primarily affect transform boundaries?
What type of geological forces primarily affect transform boundaries?
Signup and view all the answers
Which type of rocks tends to respond more brittlely than younger sedimentary layers?
Which type of rocks tends to respond more brittlely than younger sedimentary layers?
Signup and view all the answers
Study Notes
Geologic Structures
- Rocks can be folded or faulted.
- Folds are bends in rock layers caused by compression.
- Faults are planar fractures in rock bodies caused by brittle failure and relative displacement.
Strike and Dip
- Strike measures the direction of a rock layer's intersection with a horizontal surface.
- Dip is the angle at which a rock layer inclines from the horizontal, measured at right angles to the strike.
Maps, Cross Sections, and Block Diagrams
- Geological maps show the nature and distribution of surface/near-surface bedrock or materials, including their ages and types.
- Geological cross sections depict a side view of geological units, like a vertical slice through the crust.
- Geological block diagrams offer a 3D view of rock volumes, combining map and cross-section views.
Deformation of Rocks
- Forces deform rocks in three ways.
- Compressive forces squeeze and shorten rocks (brittle: reverse faulting; ductile: folding).
- Tensional forces stretch and pull rocks apart (brittle: normal faulting; ductile: crustal thinning).
- Shearing forces push sides of rocks in opposite directions (brittle: strike-slip faulting; ductile: shear folding).
Fractures in Rocks: Joints and Faults
- Joints are fractures with no appreciable movement.
- Faults are fractures with relative movement on either side.
Joints
- Joints are common in bedrock.
- They result from tectonic forces or expansion/contraction of rocks (like cooling).
Faults
- Faults have appreciable relative movement.
- They occur in mountain belts, rift valleys, and transform fault zones.
- They are caused by compression, tension, or shear.
Types of Faults
- Strike-slip faults: horizontal movement parallel to the fault plane (transform faults).
- Dip-slip faults: movement up or down the dip of the fault plane (normal and reverse).
- Normal faults: hanging wall moves down relative to the footwall (extension).
- Reverse faults: hanging wall moves up relative to the footwall (compression).
- Thrust faults: a special type of reverse fault with a low-angle dip (< 45°).
- Oblique-slip faults: combination of strike-slip and dip-slip movement.
- Overthrusts: thrust faults in which one block is pushed horizontally over another (common in mountain belts).
Folding in Rocks
- Folding is a ductile response to force, common in mountain belts.
- Large folds can extend kilometers, while small folds can be centimeters across.
- The amount of bending depends on:
- magnitude of the force
- duration of the force
- resistance of the rocks.
Fold Nomenclature
- Anticlines: upfolds (arches).
- Synclines: downfolds (troughs).
- Fold limbs: the sides of a fold.
- Axial plane: imaginary plane dividing a fold symmetrically.
- Plunging fold: a fold where the fold axis is not horizontal.
- Overturned fold: one limb tilted beyond vertical, reversing the order of younger-older layers.
Domes and Basins
- Domes: broad, circular upwarps in strata.
- Basins: bowl-shaped depressions in strata, with beds dipping inward.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz covers essential concepts of geologic structures, including folds and faults, as well as the principles of strike and dip. Additionally, it explores geological maps, cross sections, and block diagrams, highlighting their significance in understanding Earth's crust. Test your knowledge on rock deformation and geological formations!
