No. 4.] DAWSON — POST-PLIOCENE. 415 



of Scotland would necessarily be reduced to the same condition 

 with that of South Greenland or Northern Labrador. As we 

 know such a submer2;ence of the land to have occurred in the 

 Post-pliocene period, it does not seem necessary to have recourse 

 to any other cause for either side of the Atlantic. It would, 

 Iiowever, be a very interesting point to determine, whether in the 

 Post-pliocene period the greatest submergence of America coin- 

 cided with the greatest submergence of Europe, or otherwise. It 

 is quite possible that more accurate information on this point 

 might remove some present difficulties. I think it much to be 

 desired that the many able observers now engaged on the Post- 

 pliocene of Europe, would at least keep before their minds the 

 probable effects of the geographical conditions above referred to, 

 and enquire whether a due consideration of these would not 

 allow them to dispense altogether with the somewhat extravagant 

 theories of glaciation now agitated." 



It is hardly necessary to add that I hold and have endeavoured 

 to prove by modern facts, in the Memoirs above referred to, that 

 heavy icebergs borne by powerful currents, are potent agents in 

 the production of striated surfaces and glaciated stones, as well 

 as in transporting boulders, and that cold ocean currents are 

 powerful eroding agents, especially when aided by heavy ice. 

 Witness the Straits of Belle-Isle in modern times. Mr Vaushan, 

 for many years Superintendent of the Lighthouse at that place, 

 states that for ten icebergs which enter the straits fifty drift to 

 the southward, yet he records that on the 30th of May, 1858, he 

 counted in the Strait of Belle-Isle 49G bergs, the least of them 

 sixty feet in height, some of them half a mile long and two hun- 

 dred feet high. Only one-eighth of the volume of floating ice 

 appears above water, and many of these great bergs may thus 

 touch the ground in a depth of thirty fathoms or more, so that 

 if we imagine four hundred of them moving up and down under 

 the influence of the current, oscillating slowly with the motion 

 of the sea, and grinding on the rocks and stone-covered bottom 

 at all depths from the centre of the channel, we may form some 

 conception of the effects of these huge polishers of the sea-floor. 



If this memoir had not already extended to too great leno-th, 

 I could have wished to notice the evidence as to the existence of 

 ice-action in more ancient periods than the Post-pliocene. I 



