Steeply-tilted layers of flysch on the coast at Zumaia, Spain

Flysch is a sequence of sedimentary rocks that is deposited in a deep marine facies in the foreland basin of a developing orogen. Flysch is typically deposited during an early stage of the orogenesis. When the orogen evolves, the foreland basin becomes shallower and molasse is deposited on top of the flysch. It is therefore called a syn-orogenic sediment (deposited contemporaneously with mountain building).

Sedimentological properties

Flysch consists of repeated sedimentary cycles with upwards fining of the sediments. At the bottom of each cycle are sometimes coarse conglomerates or breccias, which gradually evolve upwards into sandstone and shale/mudstone. Flysch typically consists of a sequence of shales rhythmically interbedded with thin, hard, graywacke-like sandstones. Typically the shales do not contain many fossils, the coarser sandstones often have fractions of micas and glauconite.

Flysch is formed under deep marine circumstances, in a quiet and low-energetic depositional environment. The coarser layers (which require higher energy) are disruptions in these circumstances, caused by pulsewise flows of mass transport from the forming orogenic wedge. In many cases the mass transports are represented in the record by turbidites.

Other Languages
aragonés: Flysch
català: Flysch
čeština: Flyš
Deutsch: Flysch
Ελληνικά: Φλύσχης
español: Flysch
Esperanto: Fliŝo
euskara: Flysch
فارسی: فلیش
français: Flysch
galego: Flysch
hrvatski: Fliš
italiano: Flysch
ქართული: ფლიში
magyar: Flis
Nederlands: Flysch
norsk nynorsk: Flysch
oʻzbekcha/ўзбекча: Flish
română: Fliș
shqip: Flishi
slovenčina: Flyš
slovenščina: Fliš
српски / srpski: Флиш
srpskohrvatski / српскохрватски: Fliš
svenska: Flysch
українська: Фліш