GEOLOGY STUDY GUIDE
Module exam GL4 June 2005
R O C K D E F O R M A T I O N
Geology Department, Greenhead College, Huddersfield.
Syncline at Jeffrey’s Mount, Tebay
Your name …………………………………………………………… Date ………………………….
Margin notes
When you have completed this study guide, you will:
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Have understood the terms geologists use to describe rock deformation
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Have experimented on brittle and ductile materials to see how they deform
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Studied the stress fields which produce the three main fault types
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Described the evidence of faulting which can be seen in the field
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Extended your knowledge of fold types
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Learnt examples of folding types
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GEOLOGY STUDY GUIDE
Module exam GL4 June 2005
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Here is a choice of resources to use. You do not need to look at them all but clearly the more you read the better your knowledge of case studies will be. Tick the box once you have used the resource.
If you read a photocopied extract then highlight it to help you reread it for revision. If you make notes from a video tape make sure that the notes are headed with the name of the tape so that you know the source of your information. Case studies are very useful for essay questions so you should keep a separate list of the examples that you have researched.
SG1
SG2
SG3
SG4
SG5
SG6
SG7
SG8
SG9
SG10
SG11
SG12
SG13
SG14
Understanding Geology David Webster p 93-96
Geoscience Edwards and King p 136-144
Geological Science by Andrew McLeish p 147-160
Exercise on factors which affect rock deformation
Angelina unstretched . Geol. Today Nov-Dec 1992
Faulting exercise
Plunging folds exercise
Exercise on faulted folds
SWAN Rule examples
CD Rom Visualising Geology in 3D Folding and Faulting
Library Skinner, B.J. and Porter, S.C., The Dynamic Earth Chap 14
Diagrams of folds from SG3 p156
Diagram to show axial plane cleavage
Video Structural Geology Tapes 56 and 60 21 mins
Websites www.geolsoc.org.uk/ Go to Teaching Resources http://www.geolsoc.org.uk/template.cfm?name=thrust_belts http://www.geologyshop.co.uk/struct~1.htm
http://homepages.nasuwt.net/sevans/Photos_of_Formations.htm#Top%20of%20Page http://cwx.prenhall.com/bookbind/pubbooks/hamblin2/chapter7/deluxe.html
There are many other websites you could search.
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GEOLOGY STUDY GUIDE
Module exam GL4 June 2005
Margin notes
TASK 1 DEFINITIONS
Define and explain, using diagrams from SG2 p137-138:
Ductile
Brittle
Stress
Deformation
Tension
Strain
Elastic deformation
Compression
Shear
Fracture/Rupture
Elastic limit
TASK 2 PRACTICAL
Using materials such as plasticene, blackboard chalk and sponge, test how they deform under stress of different types.
Make out a table showing how each material deforms under tension and compression .
TASK 3 BRITTLE AND DUCTILE DEFORMATION
As stress increases rocks deform in different ways. Laboratory tests give results which can be graphed.
Draw Fig 8.4 from SG2 p138. Describe and explain how this particular rock deformed under stress when tested.
TASK 4 FACTORS CONTROLLING DEFORMATION WITHIN THE EARTH
Summarise how materials deform by completing the blank spaces in SG4.
TASK 5 STRAIN ELLIPSOIDS
Using plasticene or blue tack form a cube. Trace a circle on one of the faces with a pencil. Now deform it under tension, compression and shear forces. For each force, record the change in shape you observe. Strain ellipsoids are indicators which geologists use to find out about stress fields in the crust.
List the natural strain ellipsoids that might be useful for analysis by geologists.
TASK 6
Read SG5 Angelina unstretched . Geol. Today Nov-Dec 1992 and answer the questions that follow.
Deadline for Angelina unstretched answers……………………………………….
Use this box for notes
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GEOLOGY STUDY GUIDE
Module exam GL4 June 2005
Margin notes
TASK 7 FAULT TYPES
Use SG6 to remind yourself how tension, compression and shear forces produce faulting in brittle rocks.
TASK 8 STRESS COMPONENTS
The forces acting on a rock can be resolved into three principal stresses acting at right angles to one another. The stress field consists of P max
, P min and P inter
and they are shown with arrows as shown in SG2 p139.
Analyse normal, reversed and strike-slip faults in terms of stress components in the stress field by drawing diagrams using stress arrows.
TASK 9 FAULT EVIDENCE
Find a variety of types of evidence which show that faulting has taken place in a rock sequence. Use your own field notes, hand specimens, slides and photos from textbooks.
You should be able to find 6/7 forms of evidence that faulting has occurred.
TASK 10 REACTIVATED FAULTS
Read, highlight and learn this information:
A fault plane is a line of weakness in the crust at a very specific point. Subsequent stresses within the crust may be released by fracturing of rocks in the same place.
Movements along a fault can be in the same direction as initial movement, if the stress field continues in the same direction, but if the stress field changes then movements can be in the opposite direction.
It is possible for major faults to continue to be active for hundreds of millions of years, in which case the total movement on them can be many hundreds of kilometres. However on faults with repeated movements it is difficult to assess the total displacement because movement could be vertical and/or lateral in both directions.
Slickensides are a useful indicator of direction of movement on faults but they will record only the final movement. Previous slickensides will be removed by later scratches along the fault plane due to friction.
TASK 11 FOLLY DOLLY FALLS
A local example of a fault showing many interesting features can be seen in
Meltham. Bring field note books and wear wellies. You have to stand in the river to study the fault.
Date of field trip…………………………………………………………
Meeting place……………………………………………………………
Meeting time…………………………………………………….………
Use this box for notes
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GEOLOGY STUDY GUIDE
Module exam GL4 June 2005
Margin notes TASK 12 REVISE WHAT YOU KNOW ALREADY
Revise synforms, antiforms, synclines and anticlines by writing out definitions of each. Use coloured diagrams to show which rocks are youngest and which are oldest within the folds.
TASK 13 FOLD TYPES
Draw diagrams to show these features, using SG 3 p.156 or SG12 interlimb angle axial plane fold axis open fold hinge tight fold
limb
upright attitude inclined attitude amplitude overturned fold wavelength recumbent fold cylindrical fold
TASK 14 PLUNGING FOLDS
Complete SG 7 to help understand the three-dimensional appearance of plunging folds.
Remember the ASSO rule: anticlines plunge in the same direction as the V shape synclines plunge in the opposite direction.
TASK 15 AXIAL PLANE CLEAVAGE
Use SG13 to show the relationship between axial plane cleavage and bedding planes. Describe the stress field which produces axial plane cleavage. Use specimens and photos to help understand the relationship between the two.
TASK 16 FAULTED FOLDS
Look at SG8 and complete the block diagrams to show that you understand how folds and faults occur as outcrop patterns on maps.
TASK 17 CASE STUDIES OF FOLDS
Use a variety of resources to analyse folds and their terminology. Look at slides, photos in textbooks and SG9.
TASK 18 SUMMARY NOTES
You need to learn this topic now.
Summary notes deadline .........................................
Use this box for notes
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