The ptygmatic fold in nature, South Sinai, Egypt

The ptygmatic fold in nature, South Sinai, Egypt

by Metwally Hamza, Research Assistant in the field of geology with international published research papers. Academically interested in cosmic geology & planetary sciences. Geology fiend who likes to take photos of nature & geological features, Egypt

The outcrop of a ptygmatic fold in nature

• Photo description for geosciences specialists:

- Definition:
The ptygmatic fold is described as an irregular, lobate fold, usually found where single competent layers are enclosed in a matrix of low competence. Typically, ptygmatic folds do not maintain their orthogonal thickness (i.e., they are similar folds). Characteristically, their axial planes are curved.

- Reference:
Mitra, S., Datta, J. Ptygmatic structures: an analysis and review. Geol Rundsch 67, 880–895 (1978).

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• Photo description for non-specialists:

- Definition:
Primary folding in migmatites is caused by the high-temperature and high-pressure processes to which the migmatites owe their origin and composite character.

- Terminology:
1) Folding is a famous geological process by which the layers are shown to be bended, such as when you bend a paper in a systematic, geometric, or symmetric pattern.
2) Migmatite is a type of metamorphic rock that is formed when the main and original rocks are exposed to medium- and high-grade metamorphic environments, where the rocks will be changed to another one with different characterizations.
3) High-temperature and high-pressure processes are the main effective factors that facilitate the metamorphism process.

⁃ Taken and published by Geologist Metwally Hamza,
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