Where the marine and dune limestones of a Formation are seen in contact, the transition from one to the other takes three forms: 1) dunes rest upon marine deposits directly; 2) dunes rest upon marine deposits with an intervening white geosol; and 3) dunes which extend inland from the landward side of a marine deposit.

A dune limestone resting upon a marine limestone of the same Formation is a common occurrence in Bermuda's geological record. It represents a pro-gradational sequence which can be related to regression. This type of transition is frequently abrupt with no record of events occurring between marine deposition and subsequent dune deposition.