Highstand Systems Tract

Progradation

Transgressive Surface

Transgressive Systems Tract

A surface separating younger from older strata, across which there is evidence of an abrupt increase in water depth. It may be accompanied by minor submarine erosion or nondeposition, with a minor hiatus indicated. This surface often forms the maximum flooding surface (mfs), marking the boundary between the prograding Highstand Systems Tract and the top of the Transgressive Systems Tract.