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Structural Geology
I. Basic Orientation of Lines and Planes in Structural Geology
A. Orientation of plane in space
1. Attitude: orientation of structural element in space
a. planes: strike and dip
b. lines: trend and plunge
2. Bearing: compass direction orienting line in space relative to horizontal
plane
a. Azimuth vs. Quadrant
3. Strike: compass bearing of horizontal line on a plane, formed by line of
intersection between horizontal plane and inclined plane.
a. infinite no. of parallel strike lines for any inclined plane
b. data representation: azimuth direction
4. Dip: vertical angle between inclined plane and horizontal plane measured
perpendicular to strike direction
a. data: angle + direction of down dip orientation
(1) (i.e. direction water would run down the plane)
5. Apparent Dip: vertical angle between an inclined plane and a horizontal
plane that is NOT measured perpendicular to strike direction
a. Apparent dip will always be < than true dip
B. Orientation of Lines
1. Trend: compass bearing of line orientation
2. Plunge: vertical angle measured between a line and the horizontal
3. Pitch or Rake: angle measured within an inclined plane between a
horizontal line and the line in question
I. Solving Problems of Apparent Dip (Chapter 1 in lab manual, p. 1-9).
A. Problem: many outcrops are 2-D cuts in quarry walls, or road cuts
1. the road or quarry cut may not be oriented truely perpendicular to the
strike of the beds
a. hence, any dip angles measured in that cut will be represented as
"Apparent Dip"
(1) In structural analysis, we need to convert the apparent dip,
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