Folds and Folding topics include: Folds parts and classifications, folding causes and miscellaneous types. Folding is a geological process that causes rock surfaces to curve during deformation. Folds are permanent deformation structures that occur when rocks or parts of the Earth's crust are folded under compressional stress. The type of fold that forms depends on the nature of the rock and the intensity of the compressional force.  Folds are wave-like undulations in the Earth's crust. They are made up of several strata (rock layers). The plane that marks the center of the fold is called... Show more

Folds and Folding topics include: Folds parts and classifications, folding causes and miscellaneous types.

Folding is a geological process that causes rock surfaces to curve during deformation. Folds are permanent deformation structures that occur when rocks or parts of the Earth's crust are folded under compressional stress. The type of fold that forms depends on the nature of the rock and the intensity of the compressional force. 

Folds are wave-like undulations in the Earth's crust. They are made up of several strata (rock layers). The plane that marks the center of the fold is called the axial plane. The line where the axial plane intersects the surface of the Earth is called the hinge line. 

Different types of folds have been recognized based on structure, appearance, and geometry. 

Some types of folds include:
Anticline: An upfold that arches up as both sides of the rock are pushed inward. The arch looks like an "A".
Syncline: A downfold that sinks down as both sides of the rock are pushed inward.
Recumbent fold: A fold that lies down, resulting from the continuation of pressure. The axial plane and both limbs of a fold lie roughly and horizontally.
Isoclinal fold: A fold that shows differences in thickness at the crestal and the trough regions.
Asymmetrical fold: A fold where the axial plane is inclined and vertical. The limbs of the fold are parallel to each other.
Plunge fold: A folded structure that has a “dip” along the hinge line. 

Folding has resulted in the Himalayan Mountains and the Alps.

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Engineering Geology Practice Test: Folds and Folding

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25 Questions

1. The type of fold which is actually a group of folds is ____________

Isoclinal foldsAsymmetrical foldsSymmetrical foldsRecumbent folds

2. Isogans converge inwards in class 1 folds.

MaybeFalseTrueDon't Know

3. Folds characterized by well-defined, sharp hinge points are called ___________

Cylindrical foldsCuspate foldsConjugate foldsCheveron folds

4. The cause of folding which does not occur due to the tangential stresses is ___________

Flexural creepingFlexural foldingFlowage foldingShear folding

5. Which of the following is not true about cylindrical folds?

These well defined axes are not repeated parallel to each otherThey have very well defined axes of foldsThey resemble sections of pipesThese well defined axes are repeated parallel to each other

6. What would the two cross sections drawn at mutually right angle directions in a basin show?

Both charactersSynclinal charactersDrag foldAnticlinal characters

7. The minimum number of limbs for a fold are _____________

1243

8. The crest and trough may or may not coincide with the axis.

FalseMaybeTrueDon't Know

9. The anticlines signifying larger bending are called ___________

GeanticlinesGeranticlinesGeoantinclinesGeosynclines

10. Which is the type of fold with a similar degree of folding for indefinite depths?

Uniform foldConcentric foldConjugate foldSimilar fold

11. How does the thickness of the layer affect flexural folding?

Thicker the layers, greater is the slipThicker the layers, lesser is the slipThinner the layers, greater is the slipHas no effect

12. The point where the curvature is maximum is ________

NucleusHingeAxial surfaceFold point

13. The type of fold in which the limbs dip away from each other at the crest is ______________

CounterclineAnticlineDoesn’t existSyncline

14. How is the plunge of a fold measured?

DepthDirectionBoth direction and degreeDegree

15. Which among the following is not a part of fold?

Height of foldHingeAxis of foldLimbs

16. Folds which mostly occur in groups are based on ___________

Profile of the fold surfaceRelative curvatureMode of occurrencePlunge

17. Where can folds be observed in the southern part of India?

Satpura region onlyCannot be observed in southern IndiaVindhyan and Satpura rangesVindhyan region only

18. Drag folds are folds within folds.

TrueFalseMaybeDon't Know

19. The process of folding which is considered to be non-tectonic is ___________

Tangential compressionTangential tensionIntrusionsDifferential compression

20. Where is the Liddar Valley Anticline situated?

Uttarakhand HimalayasHimachal Pradesh HimalayasSikkim HimalayasKashmir Himalayas

21. Which of the following is not true about Anticline?

Geologically older rocks occupy a position in the interior of the foldThe limbs dip away from each other at the crestThey are convex downwardsThe strata are uparched

22. The displacement at the hinge point is maximum.

TrueMaybeFalseDon't Know

23. Fold with flattened top is ___________

Plateau foldBox foldSquare foldConjugate fold

24. Identify the class to which the fold below belongs to ___________

Class 1Class 3Class 4Class 2

25. Flexural folding is also called as “flexural-slip-folding”.

TrueMaybeFalseDon't Know