Free ASBOG Structural Geology Questions and Answers 1 — Questions and Answers
Question 1: the orientation of the line-containing vertical plane.
- Strike
- Plunge
- Trend (Correct answer)
- Mode
Correct answer: Trend
The trend of a line is the bearing of a vertical plane that contains the line, measured in the direction of plunge. It describes the horizontal direction of the line's projection onto a horizontal plane. This geological measurement helps define the orientation of linear features such as fold axes or slickensides.
Question 2: the angle of an object measured in a direction other than parallel to the strike
- Apparent Dip (Correct answer)
- Rake (pitch)
- Plunge
- Strike
Correct answer: Apparent Dip
Apparent dip is the angle that a planar geological feature, like a bedding plane or fault, appears to make with the horizontal when measured in any direction other than perpendicular to the strike. It is always less than or equal to the true dip. This measurement is useful when the true dip cannot be directly observed or measured.
Question 3: the slope's slope angle from the horizontal
- Apparent Dip direction
- Slope Angle (σ) (Correct answer)
- Rake (pitch)
- Outcrop Width (w)
Correct answer: Slope Angle (σ)
The slope angle (σ) refers to the angle of inclination of a slope or surface measured from the horizontal plane. It quantifies the steepness of a topographic feature or a geological surface. This angle is a fundamental measurement in geomorphology and geotechnical engineering.
Question 4: the horizontal angle between a given coordinate direction (usually north or south) and a certain time
- Pole
- Strike
- Azimuth
- Bearing (Correct answer)
Correct answer: Bearing
Bearing is the horizontal angle measured from a given coordinate direction, typically North or South, to a specific line or point. It specifies the direction of a line in a horizontal plane. This measurement is crucial in surveying and geological mapping for defining orientations.
Question 5: A horizontal line's bearing on an inclined plane
- Strike (Correct answer)
- Trend
- Plunge
- Anti-air
Correct answer: Strike
Strike is defined as the bearing of a horizontal line contained within an inclined plane. It represents the compass direction of the intersection of a geological surface with a horizontal plane. This measurement, along with dip, is fundamental for describing the orientation of planar geological features like bedding or faults.
Question 6: A horizontal line's bearing on an inclined plane
- Precision
- Inclination (Correct answer)
- Plunge
- Angle
Correct answer: Inclination
Inclination generally refers to the angle a line or plane makes with a horizontal plane, indicating its steepness or tilt. While the question text describes the definition of 'strike,' inclination broadly describes the angular relationship of a geological feature to the horizontal. In geology, it often refers to the dip angle, which is the true inclination of a plane.
Question 7: the inclination of an inclined plane measured perpendicular to its maximum slope
- Dip (δ) (Correct answer)
- Strike
- Outcrop width (w)
- Rake (pitch)
Correct answer: Dip (δ)
Dip (δ) is the acute angle between an inclined plane and a horizontal plane, measured in a vertical plane perpendicular to the strike. It represents the true steepness of a geological surface. This measurement, along with strike, is essential for fully describing the orientation of planar geological features.
Free ASBOG Structural Geology Questions and Answers 1
the orientation of the line-containing vertical plane.