ANNIVERSARY ADDRESS OF THE PRESIDENT. XXIX 



ice, as noticed by him in his communication to this Society upon the 

 Boulders of the Southern Hemisphere*, pointing out the different 

 effects produced by these various modes of transport. He remarks 

 that the fragments of rock, *' from being repeatedly caught in the 

 ice and stranded with violence, and from being every summer ex- 

 posed to common littoral action, will generally be much worn ; and 

 from being driven over rocky shoals, probably often scored. From 

 the ice not being thick, they will, if not drifted out to sea, be landed 

 in shallow places, and, from the packing of the ice, be sometimes 

 driven high up the beach, or even left perched on ledges of rock." 



Our colleague then proceeds to state the effects which would be 

 produced by the slow sinking of a mass of land in regions where 

 coast-ice could be formed, and the probable transportal of coast frag- 

 ments to higher levels as the land descended, so that, at subsequent 

 geological periods, when the land was again elevated, the hills and 

 mountain sides might be strewed over with fragments of rocks, the 

 parent mass, from whence they might have been derived, occupying 

 lower levels. 



Among the effects produced by the sinking of masses of land gra- 

 dually beneath the level of the sea, and their emergence also in a 

 gradual manner, — movements which the present state of geological 

 knowledge would lead us to suppose had been common during the 

 lapse of geological time, though not to the exclusion of more violent 

 movements (which, however vast they may appear to creatures of 

 our magnitude, examining minor portions of the earth's surface, are 

 by no means so when we regard them relatively to the volume and 

 superficies of the whole globe), — this removal of shingle and boulders, 

 with occasional angular fragments, at times and places where coast 

 ice could be formed, could scarcely but have happened. We have 

 only to consider the coasts of Northern Europe or of Northern 

 America to be gradually sinking to see how probable this would be. 

 Indeed the facts seen in connection with the distribution of boulders 

 and gravel in those regions, not forgetting a part of the scoring of 

 the solid rocks, would seem to require an explanation of this kind in 

 aid of other modes of the transport of rock fragments, none of which 

 should be forgotten when we regard the sinking, rising, or stationary 

 character of land in icy regions. Among these we should not omit, 

 for any value it may possess from local conditions, the upsetting of 

 icebergs of the kind noticed off Victoria Land. At one sudden twirl 

 the relative levels of angular fragments, shingles and boulders may 

 be changed by 1000 feet or more. "What might become of such 

 suddenly elevated portions of rocks would depend upon conditions ; 

 and we have to inquire, in the first place, by what geological changes 

 the gravel and boulders thus picked up came into a position where 

 there were no forces to round them. They might in the first in- 

 stance have been carried from the land by coast ice, and drifted 

 seaward, or may be submerged portions of old beaches, the relative 

 levels of sea and land having changed. With regard, however, to 

 this mode of suddenly altering the level of boulders, we have to re- 

 * Geol. Trans, vol. vi. 2nd series, p. 430. 



