The fold is Deleuze’s form of connection. For Deleuze, all of the universe is a process of folding and unfolding the outside – which creates an interior that is not an inside grown autonomously from the outside world, but merely a doubling of the outside. Source: 11-4-2016

A geological fold occurs when one or a stack of originally flat and planar surfaces, such as sedimentary strata, are bent or curved as a result of permanent deformation.
Source: (freely derived 11-4-2016)

Skin folds or skinfolds are areas of skin where it folds. Many skin folds are distinct, heritable anatomical features, and may be used for identification of animal species, while others are non-specific and may be produced either by individual development of an organism or by arbitrary application of force to skin, either by the actions of the muscles of the body or by external force, e.g., gravity. Skin folds are of interest for cosmetology, since often they are undesirable features (wrinkles), and for medicine, because many of them are susceptible to inflammation and infection.
Source: (freely derived 11-4-2016)

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