Intro to Geology Ch 15 Geologic Structures flashcards |

This is a Free Service provided by Why Fund Inc. (a 501 C3 NonProfit) We thank you for your donation!


(1. Click on the course Study Set you wish to learn.) (2. If you wish you can click on "Print" and print the test page.) (3. When you want to take a test...click on anyone of the tests for that Study Set.) (4. Click on "Check Answers" and it will score your test and correct your answers.) (5. You can take all the tests as many times as you choose until you get an "A"!) (6. Automated college courses created from lecture notes, class exams, text books, reading materials from many colleges and universities.)

๎„?

Long-Term Learning

Learn efficiently and remember over time.

Start Long-Term Learning

Get personalized study reminders at intervals optimized for better retention.
Track your progress on this set by creating a folder

Structural Geology

-the study of how rocks are deformed by Earth's force after lithification

Stress

-Force per unit area
~lb/cm squared

Strain

-Change in the shape & or size (volume) in response to stress

3 Types of Stress

-Compressional Stress
-Tensional Stress
-Shear Stress

Compressional Stress

-Forces push the rock together from opposite directions

Tensional Stress

-Forces pulling away from each other in an opposite direction

Shear Stress

-Stresses act parallel to a plane

3 Phases of Strain

-Elastic
-Ductile
-Brittle

Elastic

-Deformed material that recovers its original shape after stress is reduced or removed

Ductile

-Material will bend while under stress but will NOT return to its orginal shape after stress is removed

Brittle

-Material fractures at stresses higher than the strength of that material

What is elastic limit?

-limit to how far something can bend w/o breaking

How Rocks Behave When Stressed

-Rocks response to stress depend on certain parameters

Parameters of Rock Stress

-Amount of stress applied
-Rate at which stress is applied
-The composition of the rock
-Temperature at which rock is strained
-Pressure at which rock is strained

Sedimentary Structures

-Features found within sedimentary rocks that form during or after deposition but before lithification

Deformation Structures

-Features that result from the deformation of the earth's crust after lithification

Tilted Beds have a Dip Measurement

-Angle that a bedding plane dips below the Earth's surface
-two components

2 components of tilted beds

-Angula (Tilt)
-Directional (Tilt)

Angular (Tilt)

-How many degrees below the horizontal

Directional (Tilt)

-What direction the bed dips

Tilted Beds have a Strike Measurement

-Compass direction ofa line formed by the intersection of an inclined bedding plane with a horizontal plane
-Perpendicular to the dip direction

2 Components to a Strike

-Angular (Strike)
-Directional (Stike)

Angular (Strike)

-How many degrees off of due North

Directional (Strike)

-Given in two directions

How to Measure a Strike & Dip

-Find an exposed outcrop
-Find a smooth surface or create one
-Use Brunton Compass

Folds

-Bends in layered rock

Components of a fold

-Hinge lines
-Axial Plane
-Limb

Types of Folds

-Anticline
-Syncline
-Structural Domes
-Structural Basin

Anticline

-Fold shaped like an arch
-Oldest rocks in the center (core) of the fold getting progressively younger toward the edge
-Beds dip away from hinge line

Syncline

-Fold shaped like a trough
-Youngest rocks are in the core of the fold & get progressively older toward the edge
-Rock beds dip toward hinge line

Structural Domes

-Fold in which the beds dip away from a center point
-Olderst rocks are exposed at the core & get progressively younger toward the edge

Structural Basin

-Fold in which the beds dip toward a center point
-Youngest rocks are exposed at the core

Joints

-Fractures or cracks in a rock body in which no displacement has occured

3 Types of Joints

-Columnar Joints
-Sheet Joints
-Vertical Joints

Faults

-Fractures in rocks in along which sliding or displacement has occured

Drag Folds

-Minor folds produced by movement two fault blocks in opposite directions

Slickenside

-Polished & striated rock surface

Fault-Zone

-Zone of broken rock that was ground up by fault movement

Oblique-Slip Fault

-Dip-slip & strike-slip components of movement

Strike-Slip Fault

-Movement (slip) is parallel to the strike of the fault
-Horizontal or lateral faults
-Shear Stress
~ex: San Andreas Fault

Reverse Fault

-Hangingwall moves up relative to the footwall
-Compressional stress
-Thrust fault
~Low angle reverse fault
~less than 30 degrees

Normal Fault

-Hangingwall down relative to footwall
-Tensional stress

2 Types of Dip-Slip Faults

-Normal Fault
-Reverse Fault

Dip-Slip Faults

-Movement is parallel to dip direction

Please allow access to your computerโ€™s microphone to use Voice Recording.

Having trouble? Click here for help.

๎€˜
๎€—

We canโ€™t access your microphone!

Click the icon above to update your browser permissions above and try again

Example:

Reload the page to try again!

Reload

Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

๎€ 
Voice Recording

This is a Plus feature

๎€ 

๎€ 
๎€‚ Create Study Set