110 GLACIOLOGY 



Koyds would be chiefly of the nature of lateral moraine. Obviously the high level 

 terraces shown on the maja about ij to li miles easterly from Cape Koyds are of 

 the nature of marginal moraine, marking the former level to which the ice flood 

 reached up the slopes of Ross Island, at that time a gigantic nunatak. At the 

 same time it seems strange that a mass of glacier ice 1000 feet thick, moving for 

 centuries over nearly level rock surface like that in the vicinity of Cape Royds, 

 did not produce, by crushing the kenyte rock to powder, a tough boulder clay. 



If fine comminuted rock material (rock flour) was originally produced here under 

 the ice sheet it must have been washed subsequently to lower levels by sub-glacial 

 thaw-water. All that is left at present, in the way of morainic material around 

 Cape Royds, are thin and comparatively insignificant ^Datches of small boulders 

 intermixed with kenyte rubble. These are only of about a couple of acres in area, 

 and not more than about 1 foot in thickness. 



Farther east, up the foothills of Erebus, are much more extensive elongated 

 mounds and terraces, belonging to the old marginal moraine proper of the old Ross 

 Barrier. The general appearance of these moraines is shown in the frontispiece to 

 this volume. These terraces and mounds vary very much in thickness, from a few 

 feet up to 50 or 80 feet. 



In connection with these moraines of the western slopes of Erebus, Ferrar quotes 

 a statement by Dr. E. A. Wilson, that he observed near Cape Royds, during the 

 jaeriod of summer thaw, streams of water emerging from underneath these moraines. 

 Dr. Wilson concluded that 23robably there were still masses of glacier ice buried 

 under the moraines.* 



A feature of these moraines which puzzled us very much was the appearance of 

 what may be termed paths. These paths ran at various angles in relation to the 

 slope, either vertically or obliquely. 



Some suggested that they were tracks left by seals crawling inland, others that 

 they represented cracks due to irregular movements resulting from the thawing of 

 underlying masses of ice withdrawing support from the overlying moraine ; the 

 whole settling under gravity may have developed irregular cracks which became 

 channels for thaw-water, and thus the paths may have been formed.f 



The moraines, which were obviously of the nature of marginal moraines left 

 by the great ice sheet, comprised a vast number of erratics, which have been de- 

 scribed elsewhere, in the second volume, by Professor Woolnough. They comprise 

 pegmatites, often containing garnet, aplite, syenite, sodalite-syenite with wohlerite, 

 quartz-diorite, granophyric granite, porphyry, granophyre, felspar porphyry, minette, 



* It was obseived by one of us (Priestley) that the uplifted marine sliell-beds of the Cape Barne 

 district rested on ancient ice, probably a relic from the maximum glaciation. 



t It may also be suggested that these " paths " may be due to alternate expansion and contraction 

 of the morainic material. Fi-om this point of view they may be of the nature of infilled contraction 

 cracks. 



