look for places in the world where porous and permeable sands are overlain by low permeability rocks, and where conditions are right for hydrocarbons to be generated and migrate into these "traps". See also References Further reading External links Sequence Stratigraphy authoritative online encyclopedia from SEPM, a scientific society whose publications have been central to defining sequence stratigraphy. An Online Guide to Sequence Stratigraphy by the University of Georgia's Stratigraphy Lab. USC's Sequence Stratigraphy Web a fairly extensive online education resource A chart of sea level for the past 140,000 years (The different orders of cyclicity can be seen as higher frequency chatter on an overall asymmetric cycle. Today's date is on the right side of this chart.) Historical geology