Folds In Geology | Classification of Fold | Geology

Folds In Geology | Classification of Fold | Geology Introduction, to the Gemstones /watch/12=xedni&wCGzt5c2KkpDvAiaOWSlHYUU=tsil&MCqVWIaUGqPUx Volcanic Eruption ( Lava Flow) /watch/8=xedni&wCGzt5c2KkpDvAiaOWSlHYUU=tsil&YBKQHgI7X477e Rocks And Minerals | Difference between a rock and a mineral? /watch/2=xedni&wCGzt5c2KkpDvAiaOWSlHYUU=tsil&MiQWUhJidqEie A wave-like geologic structure that forms when rocks deform by bending instead of breaking under compressional stress. Anticlines are arch-shaped folds in which rock layers are upwardly convex. The oldest rock layers form the core of the fold, and outward from the core progressively younger rocks occur. A syncline is the opposite type of fold, having downwardly convex layers with young rocks in the core. Folds typically occur in anticline-syncline pairs. The hinge is the point of maximum curvature in a fold. The limbs occur on either side of the fold hinge. The imaginary surface bisecting the limbs of the fold is called the axial surface. The axial surface is called the axial plane in cases where the fold is symmetrical and the lines containing the points of maximum curvature of the folded layers, or hinge lines, are coplanar. Fold Classification Folds are classified on the basis of several geometric factors: Tightness of folding The tighness of folds can be described as open (limbs dip gently), tight (limbs dip steeply) or isoclinal (limbs are parallel). Orientation of axial plane The orientation of the axial plane relative to the horizontal together with the orientation of fold limbs allow subdivision into upright (axial plane vertical, limbs symmetric), overturned (axial plane moderately inclined, one limb overturned), or recumbent (axial plane near horizontal, one limb inverted). Thickness of folded beds Thickly-bedded, brittle units tend to form concentric folds with the bed thickness preserved normal to bedding surfaces. Thinly-bedded, clay-rich units have a tendency to develop a foliation parallel to the axial plane and form similar folds with the vertical distance between top and bottom of the unit preserved through the deformation. Types of Folds Anticline: linear, strata normally dip away from axial center, oldest strata in center. Syncline: linear, strata normally dip toward axial center, youngest strata in center. Antiform: linear, strata dip away from axial center, age unknown, or inverted. Synform: linear, strata dip toward axial centre, age unknown, or inverted. Dome: nonlinear, strata dip away from center in all directions, oldest strata in center. Basin: nonlinear, strata dip toward center in all directions, youngest strata in center. Monocline: linear, strata dip in one direction between horizontal layers on each side. Chevron: angular fold with straight limbs and small hinges Recumbent: linear, fold axial plane oriented at low angle resulting in overturned strata in one limb of the fold. Slump: typically monoclinal, result of differential compaction or dissolution during sedimentation and lithification. Ptygmatic: Folds are chaotic, random and disconnected. Typical of sedimentary slump folding, migmatites and decollement detachment zones. Parasitic: short wavelength folds formed within a larger wavelength fold structure – normally associated with differences in bed thickness Disharmonic: Folds in adjacent layers with different wavelengths and shapes. Read more : https://www.geologypage.com/2015/12/geological-folds.html#ixzz6qf1LFa6O Follow us: @geologypage on Twitter | geologypage on Facebook

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