"The principal types are fringing- reefs, barrier-reefs, shoal-reefs, reef-knolls, and bank-reefs, the last term being used to indicate reef-complexes formed over submerged highs, generally of tectonic origin. . . .The zone of interdigitation between a reef-complex and the basinward sediments is considered to be particularly favorable for the generation, migration, and accumulation of oil, subject to certain conditioning factors such as the relative development of primary and secondary porosity; or of primary or secondary lime cementation in fore-reef limestones which, if porous, may act as carrier beds and reservoirs. It is shown that the reefs grew in certain sub-littoral zones and on some submerged highs of epeiric seas covering the Arabian foreland, in which deposition of the globigerinal chalk-marl facies predominated."