A relatively conformable succession of genetically related strata bounded by unconformities or their correlative conformities. A sequence begins with a fall of relative sea level and ends with the next fall of sea-level. It is generally divided into three system tracts: lowstand (or shelf-margin), transgressive, and highstand system tracts (see individual entries and Figure S-32). The subunits of a sequence are parasequences. Sequences form in response to the interaction between the rates of eustatic changes, subsidence, and sediment supply.