STRANDED INIORAINES IN MclNIURDO SOUND 97 



also plays an important part in the transport of finer material, the snow for several 

 miles to the north of the moraines being full of grit, which is so abundant that it 

 accelerates considerably the melting of the drift-snow and the surface of the ice. 



There is a much greater proportion of pebbles and large boulders in the upper 

 layers of the morainic material than in the lower, as seen in section in the northern 

 cliff exposures. This phenomenon is partially explained by the fact that the finer 

 material would gradually be carried down by the thaw-water and used to increase 

 the compactness of the lower layers at the expense of the upper ones ; but in 

 addition it is probable that when the glacier which borders the moraines was actually 

 providing an outlet for the ice accumulating on the mountains above it, it brought 

 down its quota of morainic material from local sources, which local material would 

 reach the moraines rather in the condition of large fi-agments than as the finely 

 divided debris which is essentially the result of the prolonged trituration for which 

 a long journey is necessary. This latter explanation finds support in the abundance 

 of local erratics on that portion of the moraines nearest the shore, erratics which are 

 identical with the different great formations which crop out in the sides of the 

 glacier furrowing the western mountains. The southernmost portion of the moraines 

 is almost entirely composed of angular basaltic and kenyte debris on the seaward 

 side, the local boulders becoming more common as the landward side is approached, 

 though at the northern end of the moraines these boulders become very numerous 

 even on the extreme seaward side. As for the material which makes up the main 

 mass of the moraines, a great proportion of it must have come across the Sound, 

 because while there is no evidence of any other gi-eat outburst of kenyte material 

 besides that of Mount Erebus, large quantities of kenyte and kenytic fragmental 

 rocks were picked up during our short stay here of the Western Party.* 



An important characteristic in addition to those already noted is the very 

 isolated occurrence of some of the erratics. 



Some small conical heaps consisting entirely of fragments of one kind of rock 

 were undoubtedly, from the angular nature of the fragments, the final results of 

 the frost-weathering of very large original blocks. Not so in all cases, however. 

 In the case of one basalt tuff particularly I noticed that it was found entirely 

 covering two or three small hills at the south-eastern corner of the moraines, and it 

 was found nowhere else. The pieces were all rounded or sub-angular, and they were 

 too scattered to have been the result of the weathering of a few large boulders. 



One fact points to recent elevation of these moraines. At the north-eastern end 

 of the moraines a number of flat-topped hills and ridges were of the same height, and 

 all capped by several inches of a brownish deposit, which proved on examination 

 to be a fungus similar to those found in the lakes at winter quarters. The whole 

 district seems, therefore, to have been at quite a recent date a lake bed. The lake 

 has been elevated and drained, and its bed has been dissected by streams, whilst 



* The evidence secured by Debenham suggests that this material also may have a local origin. 



