Fold (geology)
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In structural geology, a fold is a stack of originally planar surfaces, such as sedimentary strata, that are bent or curved during permanent deformation. Folds in rocks vary in size from microscopic c
Folds of alternate layers of limestone and chert occur in Greece. The limestone and chert were originally deposited as flat layers on the floor of a deep sea basin. These folds were produced by Alpine deformation.
Kink band folds in the Permian of New Mexico, USA
Rainbow Basin syncline in the Barstow Formation near Barstow, California
Chevron folds, Ireland
Migmatite
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Migmatite is a rock formed under high-grade metamorphism by partial melting, producing a mixture of metamorphic and newly formed igneous material. It typically occurs in the deeper parts of the contin
Fold (geology)
…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…
Ptygmatic folding in migmatite on Naissaar Island, Estonia
Migmatite on the coast of Saaremaa, Estonia
Intricately-folded migmatite from near Geirangerfjord, Norway
Migmatite rock in Saaremaa, Estonia