Vol. 55.] GLACIAL PHENOMENA OP SPITSBERGEN. 687 



YI. Action of Sea-ice. 



The relative amount of action produced by the various forms of 

 sea-ice is difficult to differentiate ; scratches found on the surface of 

 submerged rocks may be due to either icebergs or floe-ice, or to 

 movements taking place in the continuous sheet of ice occupying a 

 bay in winter. Beautiful examples of scratching and grooving are 

 to be found on the surface of some of the submerged limestone-beds 

 which lie south-west of Coal Haven in King's Bay. 



Since these are covered by water, except at very low tide, their 

 glaciation cannot be attributed to the action of land-ice. They 

 form the base from which a spit of shore composed of pebbles and 

 boulders projects into the fjord, at low tide enclosing a lagoon. 

 This ridge is chiefly composed of blocks of rock dropped by icebergs 

 which have stranded in the shallow water at the edge of the reef 

 and partially melted before being carried out to sea. It is therefore 

 probable that the scratches, which here run parallel to the coast- 

 line, are produced by these icebergs. Some, however, which I 

 observed running at right angles to the coast, may have been 

 produced by the pressure of the ice covering the bay in winter due 

 to any sudden increase in the cold, when a direct thrust would 

 take place on shore, the centre of the bay becoming the radiating- 

 point, in a manner similar to that suggested by Mr. Lamplugh in the 

 case of the ice-sheet that occupied the North Sea during the Glacial 

 Period. 



As the country is known to have been rising for some time 

 past, I am inclined to think that much of the rounding of the lower 

 slopes surrounding the bay has been produced by ice of this 

 description ; and I would suggest that the smooth contours of the 

 islands to the north (and especially Walden Island, which we visited 

 during our flrst expedition to the country) were impressed on those 

 hard Archaean rocks by sea-ice during the elevation, and not by 

 glaciers originating on the mainland. It would be interesting 

 to determine, if possible, whether any particular boulder has received 

 its characteristic glaciation during the forward movement of a glacier 

 or during its voyage on an iceberg; but no definite distinction 

 between the marks produced by these difl'erent modes of origin 

 seems to exist. I was impressed, however, by the fact that the 

 majority of the boulders collected from icebergs by the Jackson- 

 Harmsworth Expedition appeared to possess one side much more 

 definitely planed and polished than the rest of the block, and I 

 found the same characteristic among many of the boulders which 

 I examined on the spot. This feature is what we might expect in 

 blocks carried by floating ice and ground against projecting reefs 

 under water, for in this case the boulder would probably retain its 

 original position in the ice until deposited on the melting of the 

 berg, and would not be constantly rolled over in the ice in the way 

 which must usually occur with fragments embedded in the lower 

 layers of a moving mass of land-ice. It is possible that this fact 

 may help to decide whether in some Glacial deposits the boulders 

 have originated in land-glaciers or floating ice. 



