292 SCOTT'S LAST EXPEDITION 



of parallel valleys. These arc about 10 or 12 miles long, and 

 are in many cases occupied by small glaciers in the western half 

 of the valley. They are identical with the ' finger ' valleys de- 

 scribed in the reports on the glacial geology of the Rocky Moun- 

 tains, U.S.A. Narrow ridges about 3000 feet high separate 

 them. Some ' hang ' a thousand feet above the Koettlitz. Char- 

 acteristic hills, triangular in plan, occur where these valleys join, 

 and all of them ' head ' in beautiful cwms. Above these cwms, 

 and more cwms, fret the scarp of Mt. Lister over the whole 

 extent of its 10,000 foot face. There is little doubt that we have 

 here an example of the way the glacial cycle commences its opera- 

 tions, for this is a fault scarp of comparatively recent date. 



(c) Granite Harbour, like New Harbour, is probably a relic 

 of the period of glacial maximum when the ice flood exerted tre- 

 mendous erosive power on its bed, and was able to erode far 

 below sea-level. We shall however never be able to witness these 

 maximum forces in operation. Because a dwindling river has 

 little effect on the topography it would be foolish to deny the 

 action of a great river in flood; just as our observations in the 

 Antarctic on a nearly stagnant or receding glaciation are not 

 to be taken as descriptive of the most active periods in glacial 

 history. 



The first feature that strikes the geologist is that as one pn> 

 ceeds north there is less and less land exposed below the snow and 

 ice mantle. This implies, I think, that the precipitation in the 

 south-west corner of McMurdo Sound is extremely little, and in- 

 creases both northward and southward. The most striking fea- 

 ture in the harbour the Ice Tongue has been described in the 

 narrative. The Mackay Glacier moves 3 feet a day, as already 

 recorded. Mention must be made of the ridge separating the 

 new glacier from the Devil's Punch Bowl. This has certainly 

 been covered quite lately by the new glacier. The harder dykes 

 are striated, but the ridge is for the most part covered with gran- 

 ite debris. There is practically no englacial rock debris in the 

 glacier, so that one is led to the important conclusion that the 

 floor of the new glacier is covered with rock debris and that no 

 erosion is taking place under this fairly large glacier. What was 

 the floor of the Mackay Glacier at its period of greater area is 

 exposed in many places 1000 feet above the sea ice in the form 

 of rock-strewn plateaux. 



