Fold (geology) in the context of "Stress (physics)"

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⭐ Core Definition: Fold (geology)

In structural geology, a fold is a stack of originally planar surfaces, such as sedimentary strata, that are bent or curved ("folded") during permanent deformation. Folds in rocks vary in size from microscopic crinkles to mountain-sized folds. They occur as single isolated folds or in periodic sets (known as fold trains). Synsedimentary folds are those formed during sedimentary deposition.

Folds form under varied conditions of stress, pore pressure, and temperature gradient, as evidenced by their presence in soft sediments, the full spectrum of metamorphic rocks, and even as primary flow structures in some igneous rocks. A set of folds distributed on a regional scale constitutes a fold belt, a common feature of orogenic zones. Folds are commonly formed by shortening of existing layers, but may also be formed as a result of displacement on a non-planar fault (fault bend fold), at the tip of a propagating fault (fault propagation fold), by differential compaction or due to the effects of a high-level igneous intrusion e.g. above a laccolith.

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Fold (geology) in the context of Alps

The Alps (/ælps/) are some of the highest and most extensive mountain ranges in Europe, stretching approximately 1,200 km (750 mi) across eight Alpine countries (from west to east): Monaco, France, Switzerland, Italy, Liechtenstein, Germany, Austria and Slovenia.

The Alpine arch extends from Nice on the western Mediterranean to Trieste on the Adriatic and Vienna at the beginning of the Pannonian Basin. The mountains were formed over tens of millions of years as the African and Eurasian tectonic plates collided. Extreme shortening caused by the event resulted in marine sedimentary rocks rising by thrusting and folding into high mountain peaks such as Mont Blanc and the Matterhorn.

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Fold (geology) in the context of Mountain range

A mountain range or hill range is a series of mountains or hills arranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have arisen from the same cause, usually an orogeny. Mountain ranges are formed by a variety of geological processes, but most of the significant ones on Earth are the result of plate tectonics. Mountain ranges are also found on many planetary mass objects in the Solar System and are likely a feature of most terrestrial planets.

Mountain ranges are usually segmented by highlands or mountain passes and valleys. Individual mountains within the same mountain range do not necessarily have the same geologic structure or petrology. They may be a mix of different orogenic expressions and terranes, for example thrust sheets, uplifted blocks, fold mountains, and volcanic landforms resulting in a variety of rock types.

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Fold (geology) in the context of Jura mountains

The Jura Mountains (/ˈʊərə, ˈʒʊərə/ JOOR-ə, ZHOOR) are a sub-alpine mountain range, a short distance north of the Western Alps, and mainly demarcate a long part of the French–Swiss border. While the Jura range proper ("folded Jura", Faltenjura) is located in France and Switzerland, the range continues northeastwards through northern Switzerland and Germany as the Table Jura ("not folded Jura", Tafeljura), which is crossed by the High Rhine.

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Fold (geology) in the context of Geodiversity

Geodiversity is the variety of earth materials, forms and processes that constitute and shape the Earth, either the whole or a specific part of it. Relevant materials include minerals, rocks, sediments, fossils, soils and water. Forms may comprise folds, faults, landforms and other expressions of morphology or relations between units of earth material. Any natural process that continues to act upon, maintain or modify either material or form (for example tectonics, sediment transport, pedogenesis) represents another aspect of geodiversity. However geodiversity is not normally defined to include the likes of landscaping, concrete or other significant human influence. Finally, geodiversity plays a prominent role in the functioning of the Earth Critical Zone, supporting the supply of multiple ecosystem services.

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Fold (geology) in the context of Continental collision

In geology, continental collision is a phenomenon of plate tectonics that occurs at convergent boundaries. Continental collision is a variation on the fundamental process of subduction, whereby the subduction zone is destroyed, mountains produced, and two continents sutured together. Continental collision is only known to occur on Earth.

Continental collision is not an instantaneous event, but may take several tens of millions of years before the faulting and folding caused by collisions stops. The collision between India and Asia has been going on for about 50 million years already and shows no signs of abating. Collision between East and West Gondwana to form the East African Orogen took about 100 million years from beginning (610 Ma) to end (510 Ma). The collision between Gondwana and Laurasia to form Pangea occurred in a relatively brief interval, about 50 million years long.

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Fold (geology) in the context of Mountain formation

Mountain formation occurs due to a variety of geological processes associated with large-scale movements of Earth's crust (tectonic plates). Folding, faulting, volcanic activity, igneous intrusion and metamorphism can all be parts of the orogenic process of mountain building. The formation of mountains is not necessarily related to the geological structures found on it.

From the late 18th century until its replacement by plate tectonics in the 1960s, geosyncline theory was used to explain much mountain-building. The understanding of specific landscape features in terms of the underlying tectonic processes is called tectonic geomorphology, and the study of geologically young or ongoing processes is called neotectonics.

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