ASBOG Structural Geology

Accuracy

How close a measurement conforms with a standard or accepted value

Apparent Dip

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

Apparent Dip Direction

The bearing of the vertical plane containing the apparent dip angle

Attitude

The orientation in space

β

The angle between strike and the apparent dip direction

Bearing

The horizontal angle between a time and a specified coordinate direction, ususally north or south

Depth (d)

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

Dip (δ)

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

Directed line

A line described by its pearing and plunge

Fold line

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

Inclination

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

Outcrop width (w)

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

Pole

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

Plunge

The vertical angle between a line and horizontal

Precision

The degree of agreement or consistency of repeated measurements

Rake (pitch)

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

Slope Angle (σ)

The angle from the horizontal down the slope

Stereonet

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

Strike

The bearing of a horizontal line in an inclined plane

Trend

The bearing of the vertical plane containing a line.