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. A fold can have differences in thickness due to erosional and depositional processes.

MaybeTrueDon't KnowFalse

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

SynclineAnticlineDoesn’t existCountercline

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

PlungeRelative curvatureProfile of the fold surfaceMode of occurrence

4. Pick the option which is not the cause of folding.

Folding due to intrusionsFolding due to differential compressionFolding due to tangential tensionFolding due to tangential compression

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

2134

6. What is a plunging fold?

Fold with fold axis only verticalThis is not a type of foldFold with fold axis horizontalFold with fold axis not horizontal

7. Which is the class of fold with the degree of curvature greater on the outer arc compared to the inner arc?

Class 2Class 4Class 3Class 1

8. Fold with flattened top is ___________

Square foldPlateau foldConjugate foldBox fold

9. All synclines and anticlines can be considered to be homoclines.

TrueMaybeDon't KnowFalse

10. What are the undulations or bends developed in rocks called?

UncomformityFaultsJointsFolds

11. Flowage folding occurs in which type of rocks?

Any rockCompetent rocksSedimentary rockIncompetent rocks

12. The fold which is associated with the formation of mountains is ___________

GeosynclineBasinGeanticlineHomocline

13. Which fold is depicted by the figure below?

DomeMonoclineHomoclineDrag fold

14. Which among the following is considered as compound anticline?

DepressionBasinDomeValley

15. What is affected when the layers of undesirable nature are encountered?

Time scheduleProject costAll the three are affectedSafety of the project

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

Recumbent foldsAsymmetrical foldsIsoclinal foldsSymmetrical folds

17. What is the reason for rock bursts?

Intense precipitationShattering of rocksStrained natureChange in attitude of rocks

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

Concentric foldConjugate foldUniform foldSimilar fold

19. Bending or warping is studied under ___________

Volcanic foldingIntrusional foldingNon-tectonic foldingTectonic folding

20. Pick the wrong statement about recumbent fold.

It has the core, which is the innermost zone, maybe made up of igneous rocks and metamorphic rocksIt has the arch, which is zone of curvatureIt has the shell, which is the outer zone, made up of mostly sedimentary rocksIt has the shell, which is the inner zone, made up of mostly igneous rocks

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

Anticlinal charactersDrag foldSynclinal charactersBoth characters

22. A fold which is not based on the profile of the folded strata is ___________

Cuspate foldConjugate foldCheveron foldPlunging fold

23. There are three types of folds classified on the basis of relative curvature of the outer and the inner arcs of a fold.

MaybeFalseTrueDon't Know

24. The displacement at the hinge point is maximum.

FalseDon't KnowTrueMaybe

25. Folds with two hinges and three planar limbs are called ___________

Cheveron foldsCuspate foldsCylindrical foldsConjugate folds