CAPE ROYDS 111 



vosgesite, porphyrite, diabase-porphyry, solvsbergite, sapphire-bearing trachyte, 

 spheruHtic trachyte, porphyritic basalt, actinolite-schist, tremolite-schist, phyllite, 

 several varieties of red and grey granites, granulites with scapolite and pyroxene, 

 and of course a plentiful admixture of kenyte and kenyte-tuffs. In places very 

 coarse porphyritic gneisses are met with amongst these erratics. Sedimentary rocks 

 had been collected from here in the form of fragments of Beacon Sandstone more or 

 less converted into quartzite, quartzite perhaps older than the Beacon Sandstone, 

 containing much titaniferous iron, fragments of saccharoidal marble, marble partly 

 silicified, oolitic limestone partly replaced by quartz and much resembling the 

 Cambrian Durness limestone of Scotland, as well as fragments of dark grey cherty 

 rocks. These old moraines containing these considerable varieties of eruptive rocks, 

 together with old sedimentary rocks, are in sharp contrast with the moraines derived 

 from Erebus proper. The latter are almost exclusively formed of kenyte lava and 

 tuff, with an occasional sprinkling of trachyte or basalt. 



In addition to these moraines forming terraces on the west slope of Erebus, 

 uplifted beaches occur at intervals amongst the terraced moraines. These are 

 described in detail under the heading of "raised beaches." Foreign boulders occur, 

 varying in size from a few inches up to 5 feet in diameter. The largest of these 

 foreign boulders are formed of the red granite which is so abundant on the 

 mainland. 



It will be noticed on the map of the Cape Royds district that these erratics of 

 red granite have a linear direction as regards their present distribution, the trend 

 of the line being about N. 30" W. 



The question may be asked, why did the Great Ice Barrier Glacier in McMurdo 

 Sound, in the neighbourhood of Cape Royds, move in a direction west of north instead 

 of due north, following the trend of the Sound, with possibly a slight set to the east 

 of north due to the component of pressure from the great western glaciers of Victoria 

 Land ? The probable explanation is, that during the period of maximum glaciation 

 the western slopes of Erebus, like its other portions, harboured large glaciers, which 

 moved off down the slopes towards McMurdo Sound in a westerly direction ; the 

 westerly component of pressure supplied by them was sufficient to slightly deflect 

 the northward moving ice of McMurdo Sound in a westerly direction. (See Fig. 2 

 of Plate XXV.) 



A large erratic of kenyte on the south-east side of Pony Lake, near our winter 

 quarters, measured 49 feet in circumference and 10^ feet high. 



The dimensions of some of the granite erratics near Cape Royds are as follows : — 



1. Red Granite, 6 feet 9 inches by 3 feet 4 inches by 2 feet. 



2. Red Granite, 11 feet in diameter. 



3. Grey Granite, 2 feet 6 inches by 2 feet by 1 foot 3 inches. 



4. Aplite, 2 feet 6 inches by 3 feet by 1 foot 3 inches. 



That these moraines of foreign erratics extend for some distance to the west of 



