Geology 3120 Describing Folds

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Geology 3120 - Describing Folds
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Outline

• Terms For Describing Folds
• Parasitic Folds
• Vergence

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Initial Layer Cake
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Direction of Closing
inflection point
inflection point - change in curvature (i.e.,
concave to convex)
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Convexity and Age of Beds

• Anticline - a fold that is convex in the
  direction of youngest beds
• Syncline - a fold that is convex in the
  direction of oldest beds

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Determining the Fold Axial Surface
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Determining the Fold Axial Surface
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Profile Plane of a Fold
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Interlimb Angle
Five Categories Gentle Open Close Tight I
soclinal
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Angularity of Interlimb Angle
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Cylindrical or Non-Cylindrical Folds
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Attitude of Axial Surface
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Fold Symmetry
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Fold Harmonics
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Parasitic Folds
Parasitic folds always verge towards
anticlines and away from synclines
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Parasitic Folds
Parasitic folds verge towards anticlines and away
from synclines
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Parasitic folds verge towards anticlines and away
from synclines
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Facing
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Vergence
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Vergence
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References
Most figures from http//earth.leeds.ac.uk/folds/
describing/folddesc.htm