Flashcards on Geological Fold Types and Orientations
Geological Fold Types & Orientations: A Student Guide
Tap to flip · Swipe to navigate
Geological folds
10 cards
Card 1
Question: What is the 'orthogonal thickness' of a fold referring to?
Answer: The thickness of the fold measured perpendicular (orthogonal) to the fold, i.e., constant when measured parallel to the axial surface.
Card 2
Question: What happens to layers in a fold according to the content?
Answer: Layer changes occur in folds; there is a systematic way such that the fold may change layers.
Card 3
Question: How is fold thickness described in the content?
Answer: Fold thickness is constant when measured parallel to the axial surface.
Card 4
Question: What are folds with planar limbs and sharp hinges called?
Answer: Chevron or accordion folds.
Card 5
Question: How is the orientation of a fold defined?
Answer: By the attitude of its axial surface (trace) and the plunge of its axis.
Card 6
Question: What does the 'plunge of the axis' refer to in fold orientation?
Answer: The angle at which the fold axis inclines from horizontal; it helps classify folds as horizontal, gently plunging, steeply plunging, or vertical.
Card 7
Question: What is a horizontal fold?
Answer: A fold whose axis is nearly horizontal.
Card 8
Question: What is a gently plunging fold?
Answer: A fold whose axis plunge lies between 10° and 45°.
Card 9
Question: What is a steeply plunging fold?
Answer: A fold whose axis plunge lies between 45° and 80°.
Card 10
Question: What is a vertical fold?
Answer: A fold whose axis is nearly vertical.