ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixiii 



Should geologists ever be convinced that some of the most gigantic 

 curvatures of Alpine strata have been the result of intense pressure, 

 so moderated in its application as to have been just sufficient to over- 

 come the resistance opposed to it, — should any of them ever declare 

 their beUef that the motion had been as insensible as the unfolding of 

 the petals of a flower, — it would not imply a more remarkable revolu- 

 tion in popular opinion than we have witnessed in reference to the 

 glacial hypothesis. Nor even then might we be entitled to pronounce 

 the process a slow one relatively to other natural operations, organic 

 and inorganic, which were simultaneously in progress. In the fourth 

 volume of our Quarterly Journal (p. 70), Mr. Hopkins, to whom you 

 have this year awarded the Wollaston Medal, has published an ex- 

 cellent paper on the elevation and denudation of the Lake district of 

 Cumberland and Westmoreland. He has undertaken, and, as it 

 appears to me, with no small success, the very difficult task of re- 

 storing, in a series of diagrams, the successive steps by which the 

 physical geography of the country attained its present condition, 

 although the changes to be accounted for, consisting of the addition 

 of several new sedimentary formations, and repeated alterations of 

 level, and denudation of rocks, were numerous and complicated. In 

 one part of his memoir he has suggested the possibility of the 

 period during which the dispersion of erratic blocks took place, ha- 

 ving extended far back in geological time, even as far as the oolitic 

 period ; an opinion which is, I think, at variance with a great weight 

 of evidence derived from the study of the boulder formation both in 

 Europe and North America. But in regard to the mode of transport, 

 Mr. Hopkins has taught us, that if the bed of the sea were suddenly 

 upUfted from 100 to 200 feet in vertical height, such an instantaneous 

 upward movement would give rise to currents having a velocity of 

 twenty-five to thirty miles an hour, and these currents might move 

 blocks of great magnitude from place to place. Thus a current of 

 ten miles an hour would be capable of propelling a block of five tons 

 weight, and its force increasing in the ratio of the square of its velo- 

 city, a current of twenty miles an hour would move a block of 320 

 tons. The experiments of Mr. Scott Russell on the velocity of waves 

 of translation, although made with much smaller waves, are supposed 

 to bear out these views*. 



* Hopkins, Quart. Joiirn. Geol. Soc. of Lond. vol. iv. p. 70, No. 13. 



