Geological magazine . Oil-generating 9. Oil accumulation in porous strata unconformable on oil-generating strata. 9. Strata tipping unconformally from an old Shore-line.—This issupposed to be the case in the Maikop Field, the oil havingaccumulated in more or less lenticular sands abutting against a shore-line of Cretaceous rocks. Such conditions are favourable to accumulation,for the porous beds are gently inclined and are sealed up at their upperends (Fig. 10).. 10. Oil accumulation in strata tipping unconformably from an old shore-line. 10. Exceptional Circumstanc
Geological magazine . Oil-generating 9. Oil accumulation in porous strata unconformable on oil-generating strata. 9. Strata tipping unconformally from an old Shore-line.—This issupposed to be the case in the Maikop Field, the oil havingaccumulated in more or less lenticular sands abutting against a shore-line of Cretaceous rocks. Such conditions are favourable to accumulation,for the porous beds are gently inclined and are sealed up at their upperends (Fig. 10).. 10. Oil accumulation in strata tipping unconformably from an old shore-line. 10. Exceptional Circumstance.—Occasionally large quantities of oilare obtained from fissures, fault-planes, planes of unconformity,cavities, etc. B. Oil Accumulations depending on Denudation.—Outcroppingpetroliferous strata have been referred to by practical men asmonoclines in contradistinction to anticlines, which at one timewere thought essential for the accumulation of oil. These monoclinesare often really limbs of denuded anticlines, and the term would be T. 0. Bosivorth— Outlines of Oilfield Geology. 55 applied to sexeral of the cases already described and to all cases wherethe oil-rocks crop out. Most of the gas and much of the lighterconstituents of the oil have generally escaped from outcropping oil-rocks, though U7ider certain circumstances valuable accumulations arefound. But oil-sands outcropping far from the anticlinal axis seldomcontain much oil. 1. Oil-sands sealed at Outc
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectgeology, bookyear1864
