Geological magazine . ralized from several system of Pygaster {Plesiechinus) macrostoma (after Wright).Apical system of P. ( Pygaster-) umbrella. ,, ,, Anorthopygus michelini (after Cotteau). ,, ,, A. orbicularis. ,, ,, Holectypiis (Holectypus) depressus. ,, ,, H. [Ccenholectypus) cenomanensis (after Cotteau). ,, ,, Discoidea cylindrica. ,, ,, Conulus albogalerus. ,, ,, Pyrina desinoulinsi. ,, ,, Hemiaster or Micraster. ,, ,, Spatangus. ,, ,, Clypeaster. ,, ,, Holaster or Eclmiocorys. Y.,—Outlines of Oilfield T. 0. BoswoKTH, , , Introduction. i iT is
Geological magazine . ralized from several system of Pygaster {Plesiechinus) macrostoma (after Wright).Apical system of P. ( Pygaster-) umbrella. ,, ,, Anorthopygus michelini (after Cotteau). ,, ,, A. orbicularis. ,, ,, Holectypiis (Holectypus) depressus. ,, ,, H. [Ccenholectypus) cenomanensis (after Cotteau). ,, ,, Discoidea cylindrica. ,, ,, Conulus albogalerus. ,, ,, Pyrina desinoulinsi. ,, ,, Hemiaster or Micraster. ,, ,, Spatangus. ,, ,, Clypeaster. ,, ,, Holaster or Eclmiocorys. Y.,—Outlines of Oilfield T. 0. BoswoKTH, , , Introduction. i iT is remarkable that in English geological literature and in ourUniversities so little attention is given to this important branch ofgeology. Probably it is because in this country petroleum occursonly in small quantity; nevertheless, in many parts of the BritishEmpire petroleum mining has become a great and increasing industry,and is one of the chief directions in which geology is of practical Geol. Mag. 1912. Plate Apical Systems of some Irregular EcLiiioidea. 2\ 0. BosKorth—Outlines of Oilfield Geology. 17 use to-daj. The writer therefore hopes that an orderly summary ofpresent knowledge may be useful. Pakt I. Theokexical Considerations. Oeigin.—Within a petroliferous formation as found to-day the oil isconcentrated in certain positions in the most porous beds, whilst oftenthe intervening rocks show little or no indication of oil. The originof the petroleum has been much discussed, especially in American,Hussian, and German literature. The theories may be placed under two heads according to thesujDposed source of the carbon. 1. Inorganic Origin.—It is held that the oil has been introducedinto the rocks from deep-seated sources in or beneath the earthscrust, where it was perhaps produced by chemical reactions betweensuch substances as water, carbonates, carbides, carbon dioxide, etc.,and some authorities maintain that the intrusion of hydrocarbons isone of the phenome
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectgeology, bookyear1864
