34 Hitchcock — Petroleum in North America. 



undergone a much greater change of level since the Tertiary epoch, is 

 not so well established. Dr. G. C. Wallich, in his admirable and 

 philosophical treatise' — with which all marine zoologists and geo- 

 logists are, or ought to be, familiar — believed that certain star-fishes, 

 which he had procured at a depth of 1260 fathoms (7560 feet), in lat. 

 59° 27' N., long. 26^ 41' W., about half-way between Cape Farewell 

 and the north-west coast of Ireland — were originally a shallow- water 

 species, but had gradually, and through a long course of generations, 

 accommodated themselves to the abnormal conditions incident on the 

 subsidence of the sea-bed." ^ 



" The Hebridean sea-bed, at very moderate depths (which Dr. 

 Wallich would call " shallow- water ") mainly consists of a soft 

 and, more or less, tenacious mud, mixed with stones of different 

 sizes, and resembling in its composition the Boulder-clay or 

 Glacial drift of Scotch geologists. It tells us of rocks ground 

 down by glaciers year after year in an arctic region; of the mud 

 produced by such attrition being carried into the sea in the melting 

 season by overwhelming floods, " non sine montium clamore " (see 

 Dr. Kane's description of the great Humboldt glacier) ; of its 

 dispersion over the sea-bed by the action of tides and currents ; of 

 the deposit thus formed being inhabited by a variety of animals of 

 a high northern type during a long and quiet course of time ; of the 

 sea-bed being elevated by slow degrees above the surface of the 

 water by an agency which we cannot satisfactorily explain, but which 

 may be volcanic, or, perhaps, steam f of the consequent extermina- 

 tion of these marine animals ; of an interval during which the raised 

 sea-bed was dry land ; of a gradual amelioration of the climate ; of 

 another oscillation of the earth's crust in a downward direction, 

 when the surface of the land, covered by its former deposit, again 

 becomes the bottom of the sea; and of a fresh succession of life 

 which is still in existence. Thus a cycle of similar events continually 

 recurs. Nothing is lost or altogether perishes ; all the old materials 

 are used up and assume new forms." 



II. — Peteoleum in North Abibkica*. 

 By Professor C. H. Hitchcock, M.A. 



nrvUEING the past six years the United States of America have 

 JL/ produced about 450 millions of gallons of Petroleum. The 

 average daily yield for the past year (1866) has been at least 12,000 

 ban-els. The business of collecting, transporting, and refining it 

 employs as many hands as either the coal or iron trade. The 

 economic importance of this commodity, therefore, demands a pass- 

 ing notice of its geological relations. 



1 The North Atlantic Sea-led, 1862. 



2 I.e. p. 41. 



3 Vide Mr. E. A. Peacock's pamphlet " On Steam, as the Motive Power in Earth- 

 quakes and Volcanoes, and on Cavities on the Earth's Crust." Jersey, 1866. 



i This notice of the geological relations of Petroleum in North America, has been 

 ohligingly furnished by the author. — Ed, 



