Bouma Sequence

The five part deposit produced by a waning turbidite flow. The deposit is split into:

  • Structureless massive sand with gravel-rich erosional base.
  • Parallel bedded sands produced by the upper flow regime.
  • Cross laminated sands with ripple marks.
  • Deposited in the lower flow regime.
  • Laminated silts.Fine pelagic muds.

A typical Bouma sequence is illustrated below, although all five units may not be developed in each flow:

Bouma Sequence a typical bouma sequence Facies


Pelagic and hemipelagic muds


Laminated silts


Cross laminated sands. Ripples


Parallel laminated sands


Massive Sands with a gravelly base
Scoured base with tool and prod marks