XXX PROCEEDINGS OP THE GEOLOGICAL SOCIETY. 



collect that after the upsetting of an iceberg, such as those off Vic- 

 toria Land and its adjoining icy barrier, there still would be a large 

 mass of ice beneath the surface of the sea, preventing the iceberg from 

 floating into shallow water. We endeayoured to show in the Address 

 of last year what would happen to these icebergs as they floated into 

 milder regions. From the thickness of the supporting ice becoming 

 less, and merely suflicient to float the coating of gravel and boulders, 

 not only might this detritus be borne to considerable distances, but 

 be really elevated above its former level. We merely allude to this 

 circumstance of mud, gravel and boulders being picked up at a depth 

 of 1000 or 1 100 feet, and brought by the upsetting of the iceberg to 

 a higher level, that it may be borne in mind, though it would not 

 so well explain the changes of level noticed within a few miles, since 

 in its original climate there might not be suflicient waste of the 

 supporting ice to allow of the whole floating into shallow water, the 

 raising of coast ice, as supposed by Mr. Darwin, being apparently an 

 eflicient and much better agent. 



The modification in the original levels of gravels and boulders by 

 the sinking and rising of masses of land, more particularly in tidal 

 seas, where the heights of tides in different localities, and therefore 

 the height of coast-beaches, would vary considerably according to the 

 conditions existing at particular times, is of itself highly interesting, 

 and it becomes the more so vrhen we have to consider the effects of 

 ice, either in the shape of shore ice, common sea floes forcing shin- 

 gles before them, or glacier ice on such coasts. Our colleague has 

 therefore done good service in thus showing how important it is pro- 

 perly to value the effects of coast ice when we have to consider the 

 manner in which gravel and boulders, now at higher levels than their 

 kno^Mi parent masses, may have been transported to such situations. 



In the paper of Mr. Smith, of Jordan Hill, on Scratched Boulders, 

 he alludes to his communication to this Society, in 1845, in which 

 he mentioned two boulders on the shores of the Gare Loch, Dun- 

 bartonshire, half imbedded in the till, both grooved in the same di- 

 rection, namely from N.N.W. to S.S.E., and concluded that the 

 parallelism was not accidental. Other boulders were subsequently 

 found by Mr. Maclaren and Mr. Smith grooved in the same direction, 

 that of the axis of the valley forming the trough of the Gare Loch. 

 Mr. Smith observes that, whatever may have been the cause of the 

 grooving, the grooves themselves were made subsequent to the depo- 

 sition of the till in that locality, and points out the difference between 

 the till and glacier moraines to which it has been likened. 



Without attempting to account for the particular phEenomena men- 

 tioned, Mr. Smith thinks it must be admitted that scratches and 

 furrows in rocks m.ust, in many instances, be ascribed to glacial action, 

 either in the shape of icebergs or of glaciers, and considers that such 

 action must have been in force in Great Britain, supposing its gene- 

 ral temperature to have once been sufficiently low. He alludes to 

 the views of I\Ir. Darwin respecting the depression of land and 

 the consequent relative raising of ice-borne boulders on the new 

 shores ; and concludes that there is evidence of a descent of the 



