CHAPTER IV 



GLACIOLOGY (continued) 



CAPE IRIZAR TO DRY VALLEY 



From Cape Irizar southwards to the Ferrav Glacier, a distance of over 150 miles, 

 the coast belongs to a somewhat sunken region on the line of the Antarctic Horst. 

 While Mount Nansen on the north rises to over 8000 feet above sea and the Royal 

 Society Range on the south to nearly 13,000 feet above the sea, there are only a 

 few of the coastal mountains within the area now being considered which exceed 

 5000 feet in altitude.* One exception to this rule is Mount Davidson, the height of 

 which is given by Scott as 8127 feet. The plateau character of the rocks is obvious. 

 An old peneplain of crystalline rocks is capped with Beacon Sandstone throughout 

 the greater part of this coastal section. The sandstone itself is mostly capped by 

 sheets of black rock, probably sills of diabase. It is possible that some of them may 

 represent contemporaneous lavas. The horst in this region is breached by transverse 

 valleys having a general east and west trend. Taken in order from north to south, 

 these are : — 



1. The Davis Glacier, with the Clarke Barrier to the north and the Cheetham 

 Ice Tongue to the south. 



2. The Harbord Ice Tongue. 



3. The Nordenskjold Ice Tongue, and Mawson Glacier with the Cotton Glacier. 



4. The Fry Glacier. 



5. The Penck Glacier. 



6. The Mackay Glacier, with the Geikie Glacier. 



Cape Irizar, a bold headland of pink granite with hornblende, biotite, and 

 allanite, traversed by dykes of lamprophyre, forms possibly part of a long island, 

 Lamplugh Island, trending north by east and south by west. To the south it is 

 bounded by the Cheetham Ice Tongue. On the north it is bounded by Geikie 

 Inlet, and on the west by the Clarke Barrier. The island, if it be an island,! 



* Viewed from the top of Mount Erebus by Priestley and a sledge party of the Scott Expedition of 

 1910-13, mountains seen far inland at the back of Granite Harbour, i&c, appeared to rise to heights 

 of over 8000 feet. 



t The uncertainty is due to the fact that inland it dips sharply under the low-lying ice sheets 

 of the Clarke Glacier and Davis Glacier, and it is just possible that it may prove eventually to be a 

 peninsula, but it is probably an island. 



