Geology: Understanding Folds

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What is the defining characteristic of a recumbent fold?

It is a secondary structure in folded rocks

It has undergone 180 degrees rotation

It is a partially overturned fold (correct)

It has straight limbs and sharp hinges

What distinguishes domes from basins?

Domes are semi-spherical, basins are semi-ellipsoidal

Domes have older rock layers in the center, basins have younger rock layers in the center (correct)

Domes have the youngest rock layers on the outer limbs, basins have the youngest rock layers in the center

Basins are typically represented by concentric rings, domes are not

What type of stress typically leads to the formation of chevron folds?

Compressive stress (correct)

Tensile stress

Normal stress

Shear stress

What distinguishes ptygmatic folds from disharmonic folds?

Ptygmatic folds are regular in shape, disharmonic folds are irregular in shape Signup and view all the answers

In a folded rock structure, what are parasitic folds?

Small asymmetric structures that form within large folds Signup and view all the answers

What causes plunging folds to form?

Compression in more than one direction Signup and view all the answers

Which criterion is used to classify the tightness of folding?

Size of the angle between the limbs of the folds Signup and view all the answers

What is the defining characteristic of a dome?

Concentric rings of rock layers Signup and view all the answers

What feature distinguishes chevron folds from other types of folds?

Zig-zag pattern Signup and view all the answers

Why do ptygmatic folds appear chaotic and disjointed?

Greater viscosity than surrounding material Signup and view all the answers

What causes basins to appear as deep rounded depressions?

Formation from intersecting synclines Signup and view all the answers

In what type of fold do parasitic folds form?

Recumbent fold Signup and view all the answers

What type of rock layers typically cause the formation of chevron folds?

Alternating rock layers of different compositions Signup and view all the answers

Why do plunging folds have an inclined hinge?

Application of compressional stress in more than one direction Signup and view all the answers

What distinguishes thickly-bedded rocks in terms of folding?

Retain thickness during folding Signup and view all the answers

What classification criteria indicates isoclinal folds?

Tightness of folding Signup and view all the answers