Traps can be categorized by defining the relationship of the seals with respect to the reservoir/seal bounding surface(s). Two major subdivisions provide the foundation of the classification; one-seal traps are structures which possess closed contours at the reservoir/seal interface, whereas poly-seal traps are those where closed contours at the reser-Classification schemes A trap classification scheme can help to improve trap descriptions, aid comparisons between traps and assist in grouping trap examples. Current classifications are not specific to