ANOTHEE POSSIBLE CAUSE OF THE GLACIAL EPOCH. 1G5 



Professor Cooke describes the abundant fossil remains of 

 elephants which he found in Malta, and draws from this fact, as 

 also from the existence of like fossil bones in Sicily, the conclu- 

 sion that these islands 073ce formed part of the African continent,^ 

 previous to a considerable submersion of land now constituting- 

 deep sea. 



Professor Hull beautifully explains how we can find Arctic 

 forms of marine mollusks in rocks not so far from London, and 

 proves the possibility of there having once been extensive glaciers 

 on loftier mountains in Scotland, and of which we still find the 

 scratches. 



Will the professor permit me to suggest that it would be a most 

 important point, in order to corroborate his views regarding the 

 assumption of a mean lower temperature of 10° F., previous to 

 the formation of the Gulf Stream, to take accurately into account 

 the longitudinal breadth of the Atlantic previous to the submer- 

 gence of the Continental shelf and of the Blake plateau, i.e., 

 during the Pliocene and Pleistocene epochs, by ascertaining 

 whether there are corresponding j)roofs of submergence of the 

 South American continent, even of the African coast, for evi- 

 dently tlie length of time the superficial ocean current was subject 

 to the rays of a tropical sun would have an effect analogous to 

 what takes place now in the Gulf of Mexico ? 



Professor Hull's able paper is calculated to open ou^t a vast 

 field of important geological investigations. The depression of 

 the Atlantic coasts of N"orth America and of North- Western 



Scandinavia at different periods ; in the first map he endeavoured to 

 prove the existence of a continuous ice barrier from Greenland to St, 

 Petersburg, coming down as far south as Denmark and North Germany. 

 The next map showed the retreat of the limit of eternal snow and ice, 

 the line passing thi-ough central Sweden ; while in another map the 

 glaciers were confined to certain mountainous tracts of Norway ; Sweden 

 and Finland being out of the question. This is no mere conjecture. 

 Professor Neovius, of Helsingfors University, in a iirolonged conversation 

 I had with him on this subject, declared that the deductions were 

 founded on tha geographical distribution of the granite ice-borne boulders 

 abundantly found along more than 15° of longitude in consecutive order. 



I found that glacial boulders of Finnish granite were well known to 

 exist in the neighbourhood of Halle, while I was engaged at work at 

 Eisleben, but in Finland and Sweden the boulders are more common 

 along the edge of the former isotherm of 32°. 



