Chapter 2 - Structural Geology Key Terms

Question 1

Accuracy

Answer 1

How close a measurement conforms with a standard or accepted value

Question 2

Apparent Dip (α)

Answer 2

The inclination of a plane measured in a direction NOT perpendicular to strike

Question 3

Apparent Dip Direction

Answer 3

The bearing of the vertical plane containing the apparent dip angle

Question 4

Attitude

Answer 4

The orientation in space

Question 5

ß

Answer 5

The angle between strike and the apparent dip direction

Question 6

Bearing

Answer 6

The horizontal angle between a line and a specified coordinate direction, usually north or south

Question 7

Depth (d)

Answer 7

The vertical distance from the ground surface downward to a feature of interest

Question 8

Dip (δ)

Answer 8

The inclination of the line of greatest slope of an inclined plane, measured perpendicular to strike

Question 9

Directed Line

Answer 9

A line described by its bearing and plunge

Question 10

Fold Line

Answer 10

A hinge line along which a vertical cross section may be constructed and then flattened out to a horizontal or map view

Question 11

Inclination

Answer 11

A general term for the vertical angle between the horizontal and a plane or line, measured downward

Question 12

Outcrop Width (w)

Answer 12

The width of an outcrop, as measured on a map view, perpendicular to strike

Question 13

Pole

Answer 13

A line perpendicular to a plane, and represented as a point on a stereographic projection

Question 14

Plunge

Answer 14

The vertical angle between a line and horizontal

Question 15

Precision

Answer 15

The degree of agreement or consistency of repeated measurements

Question 16

Projection

Answer 16

The process by which points on one surface are transferred to another surface, such that in each view (map or cross section) the points correspond

Question 17

Rake (Pitch)

Answer 17

The angle measured in a specified plane, between a line and the horizontal

Question 18

Slope Angle (σ)

Answer 18

The angle from the horizontal down to the slope

Question 19

Stereonet

Answer 19

A representation of angular relationships between planes and lines. In structural geology, a stereonet is synonymous with Wulff net, and equal angle stereographic projection

Question 20

Strike

Answer 20

The bearing of a horizontal line in an inclined plane

Question 21

Thickness (t)

Answer 21

The perpendicular distance between the top and bottom of a geologic unit

Question 22

Trend

Answer 22

The bearing of the vertical plane containing a line