explain the structure of flame

A flame structure is a type of soft-sediment deformation that forms in unlithified sediments. The weight of an overlying bed forces an underlying bed to push up through the overlying bed, generally when both strata are saturated with water. The resulting pattern (in cross section) may resemble flames. In order for the flame structure to occur, the overlying bed must be of a higher density than the underlying bed, or there must be differential pressures in the upper bed.

A term introduced by Walton (1956, p. 267) for a sedimentary structure consisting of sharp-crested wave- or flame-shaped plumes of mud that have risen irregularly upward into an overlying layer, generally a rapidly deposited sand. The flames, though irregular in shape, are generally overturned predominantly in one direction, which is the paleocurrent direction of the overlying sand.

Flame structures are closely allied to load structures (q.v.): they are probably formed by sinking of rapidly-deposited, therefore easily liquefied, sand into an underlying unconsolidated mud, while continued flow of the current depositing the sand produces a shear stress that results in down-flow vergence of the flames. They were formed experimentally by Kuenen and Menard (1952). Flames may also be roughly parallel to the current, forming part of the structure called “longitudinal ridges and furrows” by Dzulynski and Walton (1965, p. 66).