Sedimentology

Varve

A thin layer of fine-grained sediment deposited in still waters which occur in rhythmic bands. Varves form in a variety of marine and lacustrine depositional environments from seasonal variation in clastic, biological, and chemical sedimentary processes. The classic varve is a light to dark coloured couplet deposited in a glacial lake melting of the ice carrying sediment into the lake. The light layer usually deposited in summer. During winter months, when sediment input is reduced, fine clay-size sediment is deposited forming a dark coloured layers.

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Wadi

A wadi is a river bed in an arid region that is dry apart from times of high rainfall. The term is Ariabic in origin. The result of a flash flood is a poorly sorted sediment, which can contain substantial boulders.

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Weathering

The process of disintegrating rocks in the near surface by chemical or physical means.