Chapter 9

Question 1

Deformation

Answer 1

process by which rocks bend, break, or flow in response to “stress” (compression, tension, or shear- ing)

Question 2

Deformation produces

Answer 2

joints (cracks), faults (fractures on which one body of rock slides past another), folds (bends, curves, or wrinkles of rock layers), and foliation (layering of fabrics resulting from the alignment of min- eral grains or the development of compositional bands)

Question 3

Contrast brittle and ductile deformation

Answer 3

brittle: cracking into pieces like a glass plate ductile: squeezing and becoming larger like dough under a book

Question 4

What factors determine whether a rock will behave in brittle or ductile fashion?

Answer 4

• temperature - pressure - deformation rate -composition

Question 5

How are stress and strain different?

Answer 5

stress- acting on a plane as the force applied per unit area of the plane strain- deformation in rock as result of stress

Question 6

How is a fault different from a joint?

Answer 6

there is little to no lateral movement across joints. This makes joints different from a fault which is defined as a fracture in rock in which one side slides laterally past the other with a displacement that is greater than the separation between the blocks on either side of the fracture

Question 7

How do you recognize faults in the field?

Answer 7

Faults may be recognized in the field three ways. (1) First as an abrupt change in elevation when the surrounding area is not similarly uplifted. (2) Second when there are dipping sediments that show an offset on either side of a line or trace of a presumed fault. (3) Third when there is a repeat of the sedimentary layers vertically. This last one is tricky as you need to know the expected sedimentary sequence for the area.

Question 8

Describe the differences between an anticline, a syncline, and a monocline

Answer 8

anticlines: folds that shaped like an arch libs dip away from hinge synclines: limbs dip toward hinge monocline: resembles a carpet draped over a step ladder

Question 9

Discuss the relationship between foliation and deformation

Answer 9

ductile deformation can cause tectonic foliation

Question 10

Describe the principle of isostasy

Answer 10

the condition that exists when the buoyancy force pushing lithosphere up equals the gravitational force pulling lithosphere down

Question 11

Deformation

Answer 11

Question 12

Stress

Answer 12

Question 13

Faults

Answer 13

Question 14

Folding

Answer 14

Question 15

craton

Answer 15

A long-lived block of durable continental crust commonly found in the stable interior of a continent.

Question 16

orogen

Answer 16

(or orogenic belt) A linear range of mountains.

Question 17

vein

Answer 17

A seam of minerals that forms when dissolved ions carried by water solutions precipitate in cracks.