Vol. 54.] AND THE CORALLINE CRAG. 353 



porphyry found at the base of the Coralline Crag at Sutton, 

 which was held by Prestwich to indicate the presence of 

 floating ice in the Crag basin, occurring in a bed full of 

 derivatives, and being possibly itself derived from some older 

 formation. 



11. That Prestwich's theory of a temperature sufficiently cold to 



produce floating ice during the Coralline Crag period is in 

 entire opposition to the palaeontological evidence, which 

 indicates that the climate was at that time not colder but 

 warmer than the climate of Great Britain at the present day, 

 more nearly approaching that of the Mediterranean or the 

 Azores. 



12. That, so far from it being possible to separate the Coralline 



Crag into eight constant zones, the division of this formation 

 hitherto adopted into shelly incoherent sands and indurated 

 ferruginous rock can no longer be maintained, the latter being 

 merely an altered condition of the former, as proved not only 

 by general considerations, but by the discovery of a section 

 at Iken, showing the two varieties of Crag side by side, and 

 passing into each other. 



13. That with the exception of the basement-bed, 1 foot only in 



thickness, the material of the Coralline Crag is of similar 

 character throughout, being almost entirely organic, with only 

 a small admixture of inorganic matter ; nor is any essential 

 difl'erence between the diflerent parts of it distinguishable, 

 either by microscopical examination or chemical analysis. 



14. That, excluding the basement-bed before mentioned, the Coral- 



line Crag was throughout accumulated under similar condi- 

 tions : namely, in the form of submarine banks, caused by 

 currents, which prevented deposition when they ran strongly, 

 but swept up from the sea-bottom the remains of moUusca, 

 etc.,*redepositing them in more sheltered situations. 



15. That such conditions occur at the present day in the Irish 



Sea, as for example off the Antrim coast, where an accumu- 

 lation of dead shells, known as the Turbot Bank, has been 

 caused by the tidal currents which sweep with much velocity 

 through the narrow channel separating Ireland from Scotland; 

 and also at the southern end of the Isle of Man, where deposits 

 mainly composed of organic material, called by Prof. Herd- 

 man ' neritic,' exist, being similarly caused by a strong 

 current running through the Calf Sound. Sandbanks 

 caused by tidal currents occur along the coast of East Anglia 

 at no great distance from the shore, and more or less parallel 

 to it. 



16. That during the deposition of the Coralline Crag, the Grerman 



Ocean was less open to the north than it is at present, if, 

 indeed, it was not entirely closed, but that it was connected 

 with the Atlantic by a strait or channel over some part of 

 the southern counties of England, through which currents ran 

 strongly, and that the influence of these currents extended 



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