Bouma sequence

Bouma sequence: Sequence first recognised in sedimentary rocks composed of five intervals that make up a complete turbidite succession. It develops as a graded interval (A), a lower interval of parallel laminations (B), an interval of current ripple laminations (C), an upper interval of parallel laminations (D), and a fine-grained shaly (pelitic) interval (E). Forms a sequence that grades upward from one part into another (A to B). Partial sequences, particularly A and B, are most commonly preserved.