Chapter 10 Crustal Deformation

Front 1

anticline, p. 308

Back 1

A fold that is convex upward. Some anticlines are so eroded that all that can be seen on the surface of the earth is the trace of the fold limbs. Compare with syncline.

Hint 1

an anticline resembles an arch

Front 2

basin, p 311

Back 2

A synclinal structure, roughly circular in its outcrop pattern, in which beds dip gently toward the center from all directions.

Hint 2

basins are sometimes called doubly plunging synclines.

Front 3

brittle failure, p 306

Back 3

Structural behavior in which a material deforms permanently by fracturing.

Hint 3

brittle failure usually occurs suddenly

Front 4

compressional stress, p 303

Back 4

Any differential stress that shortens a rock body

Front 5

deformation, p 302

Back 5

general term referring to all changes in the original form of a rock body, or the original size of a rock body, or both

Hint 5

deformation can be caused either by compression or extension. It includes faulting, shearing, and folding.

Front 6

detatchment fault, p 315

Back 6

a nearly horizontal underground fault separating rocks exhibiting ductile deformation from rocks exhibiting brittle deformation. These faults may extend laterally for distances of fifty miles.

Hint 6

OMIT

Front 7

differential stress, p 303

Back 7

forces that are unequal in different directions

Front 8

dip, p. 308

Back 8

The angle that a rock or a structural surface such as a bedding plane or fault surface makes with the horizontal. Dips are always measured perpendicular to the strike and measured in refernce to the vertical plane.

Front 9

dip-slip fault, p 314

Back 9

A fault on which the movement is parallel to the dip of the fault plane

Hint 9

dip-slip faults show fault scarps.

Front 10

dome, p 311

Back 10

An uplift or anticlinal structure, roughly circular in its outcrop exposure, in which beds dip gently away from the center in all directions.

Hint 10

domes are sometimes called doubly plunging anticlines

Front 11

ductile deformation, p 306

Back 11

Structural behavior in which a material deforms permanently without fracturing

Hint 11

ductile deformation involves reversible solid state flow. This type of deformation often occurs at depths where both temperatures and confining pressures are high.

Front 12

fault, p. 312

Back 12

The surface of rock rupture along which there has been differential movement of the rock on either side.

Front 13

fault-block mountain, p 314

Back 13

Mountain bounded by one or more faults. The mountain mass is created either by the uplift of land between faults or the subsidence of land outside the faults. These uplifts and downdrops are horsts and grabens.

Hint 13

The Basin and Range of the western USA is a cluster of fault block mountains.

Front 14

fault scarp, p 314

Back 14

The fault scarp is a cliff-like feature on the surface of the earth that looks like a step. It is caused by vertical or oblique slip on the fault.

Hint 14

The scarp is the exposed above-ground surface of the fault. Scarps erode away over time.

Front 15

fold, p 308

Back 15

A bent layer of rock or a bent series of layers of rock that was originally horizontal and deformed by compressive forces.

Front 16

force, p 302

Back 16

A force is a "push" or "pull" experienced by a mass m when it is accelerated.

Hint 16

The mass can be at rest initially, or in motion and accellerated or decellerated by the force.

Front 17

graben, p 315 omit

Back 17

A valley caused by extension of the Earth's crust. Grabens are formed by the downward displacement of a fault-bounded block.

Hint 17

OMIT for 2006
The faults bordering grabens are always normal faults because they develop in areas of extension.

Front 18

hogback, p 311 OMIT

Back 18

A sharp ridge with steeply sloping sides, produced by erosion of the broken edges of highly tilted strata.

Hint 18

OMIT FOR 2006 Hogbacks are made of rock that are more resistant to erosion than adjacent rocks in the area.

Front 19

horst, p 315 OMIT

Back 19

An elongate, relatively uplifted crustal unit or block bounded by faults on its long sides. Compare with "graben"

Hint 19

OMIT FOR 2006 As with grabens, the faults bounding horsts are always normal faults because horsts and grabens form in areas of extension.

Front 20

joint, p 320

Back 20

A surface of fracture in a rock without displacement

Hint 20

There is no movement along the fracture in a joint.

Front 21

klippe, p. 318 OMIT

Back 21

a surficial remnant of a thrust sheet that has been isolated by erosion

Hint 21

OMIT FOR 2006 klippes are geological features found only in thrust fault terranes, where a mass of exotic stata has been thrust over an area. The klippe itself is an isolated rock unit that is a fragment of the thrust sheet that has not been eroded away.

Front 22

monocline, p 310

Back 22

A simple stairstep fold, described as a one-limbed flexure. On both sides of a monocline, the stata are flat-lying or only gently dipping.

Hint 22

monoclines can be very subtle structures difficult to define in outcrop pattern.

Front 23

normal fault, p 314

Back 23

A dip-slip fault on which the hanging wall block is offset downward relative to the foot wall block. Compare with reverse fault

Hint 23

normal faults often have fault scarps that are eroded away over time

Front 24

reverse fault, p 314

Back 24

A dip-slip fault on which the hanging wall block is offset upward relative to the foot wall block. Compare with normal fault .

Front 25

rock structure, p 307

Back 25

all features created by the processes of deformation, ranging from minor fractures in bedrock to a mjaor mountain chain.

Front 26

shear, p. 303

Back 26

stresses that cause two adjacent parts of a body to slide past one another

Hint 26

The slippage occurring between individual playing cards when the top of the stack is moved relative to the bottom is "shear".

Front 27

strain, p 304

Back 27

irreversible changes in the shape or size of a rock body caused by stress

Front 28

stress, p 302

Back 28

force applied to a given area

Hint 28

stress acts on solid surfaces only. Gasses and liquids cannot be stressed.

Front 29

strike, p 308

Back 29

The compass direction of the intersection between a structural surface (e.g., a rock's bedding plane or a fault surface) and the horizontal

Hint 29

strike is always perpendicular to dip.

Front 30

strike-slip fault, p 319

Back 30

A fault on which the movement is horizontal.

Hint 30

Strike slip faults are called lateral or transform faults. Movement is parallel to the fault's strike.

Front 31

syncline, p 308

Back 31

A fold that is convex downward. Compare with anticline.

Hint 31

Some synclines are so eroded that all that can be seen on the surface of the earth is the trace of the fold limbs.

Front 32

tensional stress, p 303

Back 32

Any force that elongates or pulls apart a rock unit

Hint 32

also makes the unit thinner

Front 33

thrust fault, p 317

Back 33

A low-angle reverse fault

Hint 33

some definitions make the cut-off point at 15 degrees, and not 45 degrees, as stated in your text.

Front 34

transform fault, p 319

Back 34

A plate boundary that ideally shows pure strike-slip movement. Associated with the offset segments of midocean ridges.

Hint 34

Lithosphere is neither created nor destroyed at transform faults. It is merely "moved elsewhere".

Front 35

structural geologist

Back 35

a scientist studying the architecture and processes responsible for deformation of Earth’s crust

Front 36

elastic deformation

Back 36

Non-permanent structural deformation during which the amount of deformation (strain) is proportional to the stress

Hint 36

if you apply stress, and then remove the stress, and if the rock returns to size and shape it had originally, then elastic deformation has taken place