Exam 1

Question 1

Strike and Dip using (180, 60)

Answer 1

180/60 W

Question 2

Strike Definition

Answer 2

Azimuth of an imaginary line that lies in the plane of a surface and is everywhere at the same elevation.

Question 3

Dip Definition

Answer 3

Steepest angle of inclination in the plane, always orthogonal

Question 4

Rake Definition

Answer 4

Orientation of a line that lies in a plane

Question 5

Plunge Definition

Answer 5

Vertical inclination, measured as an angle downward from the horizontal

Question 6

Pole Definition

Answer 6

Orientation of a line drawn at right angles to the plane

Question 7

Trend Definition

Answer 7

Horizontal direction of the strike, direction of plunge

Question 8

Anticline

Answer 8

Oldest rocks towards the interior

Question 9

Syncline

Answer 9

Youngest rocks near the center

Question 10

Antiform

Answer 10

Upward closing, limbs dip away from the hinge

Question 11

Synform

Answer 11

Downward closing, limbs dip towards the hinge

Question 12

Stereonet

Answer 12

Spherical projection. Not for location data, for orientation data.

Question 13

Beta plot

Answer 13

Strike and dip

Question 14

Pi plot

Answer 14

Poles for strike and dip

Question 15

Interlimb Angle

Answer 15

It is the angle subtended by the tangents at two adjacent inflection points, which may reflect the intensity of compression.

Question 16

Class 1 Fold

Answer 16

Thinner hinge and thicker limbs, inner < outer.

Question 17

Class 2 Fold

Answer 17

Thicker hinge, thinner limbs. Inner = outer.

Question 18

Class 3 Fold

Answer 18

Thickest hinge, thinnest limbs. Inner > outer.

Question 19

Buckling

Answer 19

Response to compression in direction parallel to layering. Strong contrast in material properties between layers. Competent layer in weak matrix is shortened parallel to the length of the layer.

Question 20

Chevron

Answer 20

Lower temperature, compressional. A structural feature characterized by repeated well behaved folded beds with straight limbs and sharp hinges. Well developed, these folds develop repeated set of v-shaped beds. 120, symmetric.

Question 21

Kink

Answer 21

Tabular fold-zones resulting from the operation of a shear couple and commonly occur as conjugate sets, usually developing late in the structural history of orogenic systems. 60, asymmetric.

Question 22

Shear

Answer 22

Layering does not contribute to compression of the fold, structure is from shear folding. Typically class 2 and parasitic folding.

Question 23

Bending

Answer 23

Externally applied load, monoclinic.

Question 24

Unconformity

Answer 24

Put simply, an unconformity is a break in time in an otherwise continuous rock record

Question 25

Disconformity

Answer 25

a break in a sedimentary sequence which does not involve a difference of inclination between the strata on each side of the break.

Question 26

Nonconformity

Answer 26

Nonconformities are unconformities that separate igneous or metamorphic rocks from overlying sedimentary rock

Question 27

Hinge

Answer 27

The hinge of an anticline refers to the location where the curvature is greatest, also called the crest

Question 28

Crest point

Answer 28

Highest point of antiform

Question 29

Crest line

Answer 29

A line on a folded layer which is common to and links the highest points on that layer.

Question 30

Trough Point

Answer 30

Lowest point on a synform

Question 31

Trough line

Answer 31

The line occupying the lowest part of the fold

Question 32

Plunging Fold

Answer 32

A fold that is tilted downwards in space, parallel to the fold hinge plane.

Question 33

Overturned

Answer 33

has the axial plane inclined to such an extent that the strata on one limb are overturned

Question 34

Basin and Dome

Answer 34

Domes and basins are structures with approximately circular or slightly elongate, closed outcrop patterns. Domes are convex upward; basins are concave upward.

Question 35

Disharmonic

Answer 35

A fold which exhibits sharp changes in its geometric properties (i.e. wavelength, symmetry, and shape) when compared with other folds in adjacent layers.

Question 36

Harmonic

Answer 36

A fold which maintains its geometric form, integral wavelength, and symmetry throughout a sequence of layers.

Question 37

Parasitic

Answer 37

Typical structures in geological multilayer folds; they are characterized by a small wavelength and are situated within folds with larger wavelength.

Question 38

Category: Gentle

Answer 38

Interlimb Angle: 180-170

Question 39

Category: Open

Answer 39

Interlimb Angle: 170-90

Question 40

Category: Tight

Answer 40

Interlimb Angle: 90-10

Question 41

Category: Isoclinal

Answer 41

Interlimb Angle: 10-0

Question 42

Category: Fan

Answer 42

Interlimb Angle: <0

Question 43

Subhorizontal

Answer 43

Hinge Line Plunge: 0-10

Question 44

Gently Plunging

Answer 44

Hinge Line Plunge: 10-30

Question 45

Moderately Plunging

Answer 45

Hinge Line Plunge: 30-60

Question 46

Steeply Plunging

Answer 46

Hinge Line Plunge: 60-80

Question 47

Subvertical

Answer 47

Hinge Line Plunge: 80-90

Question 48

Upright

Answer 48

Axial Surface Dip: 90-80

Question 49

Steeply Inclined

Answer 49

Axial Surface Dip: 80-60

Question 50

Moderately Inclined

Answer 50

Axial Surface Dip: 60-30

Question 51

Gently Inclined

Answer 51

Axial Surface Dip: 30-10

Question 52

Recumbant

Answer 52

Axial Surface Dip: 10-0 A recumbent fold has an essentially horizontal axial plane.

Question 53

Axial Surface

Answer 53

The imaginary surface bisecting the limbs of the fold.

Question 54

Hinge Line

Answer 54

Where limbs of the folds meet.

Question 55

Cylindrical Fold

Answer 55

Can be traced by a single line with a consistent trend-plunge

Question 56

Non-cylindrical

Answer 56

The hinge lines, inflection lines, trough lines and crest lines may be curved and irregular.