CHAPTER V 

 GLACIOLOGY {contmued) 



THE FERRAR GLACIER AND CAPE ROYDS AREA 



THE FERRAR GLACIER AND DRY VALLEY 



We now approach the southern end of the low-lying part of the great horst. As 

 already stated, this relatively low-lying part extends from Mount Nansen on the 

 north to the Royal Society Range on the south. 



The Royal Society Range is a huge horst within a horst, rising to altitudes of 

 over 12,000 feet above sea-level. The precise trend of the tectonic disturbances 

 which cause the downthrow to the north of the Royal Society Range is not known, 

 but the great fracture on which Mounts Erebus, Terra Nova, and Terror are 

 situated trends nearly due east and west. This fault line should intersect the west 

 shore of McMurdo Sound between Cape Bernacchi and New Harbour. The huge 

 massif of the Royal Society Range shoulders away the inland ice streams, compelling 

 them to make a long detour in part to the south through the Skelton Inlet, in part 

 to the north through the Ferrar Glacier and its branches. For a distance of at 

 least 30 miles south of the Ferrar Glacier (possibly 50 miles, if the Koettlitz 

 Glacier is not an outlet glacier from the plateau) there is no breach in this mighty 

 wall of rock. This stemming action, forcing the inland ice streams to flow along 

 lines of weakness in the rocks induced by parallel faulting just north of the Royal 

 Society Range, contributes to make this area an important outlet region. An 

 examination of Ferrar 's geological maj) shows that the lower part of the Ferrar 

 Glacier, with its trend prolonged inland up the glacier South Arm, the North Fork 

 Glacier with Dry Valley, and three other valleys which adjoin it in succession 

 northward, together with the Mackay Glacier, have an approximately parallel trend. 

 This trend is about E.N.E., with a tendency to become more easterly as Granite 

 Harbour is approached. For the upper 50 miles of its course the Ferrar Glacier 

 has a W.N.W. to E.S.E. trend. It is clear from the physiography of the district 

 that the Ferrar Glacier is now but a shrunken remnant of its former self. 



Ferrar states * in speaking about the corrie glaciers at the north side of the 

 head of the Ferrar Glacier at the Inland Forts, " All flow southwards, but fail to 

 reach the ice of the main valley, and are now building ujj crescentlc moraines at 



* National Ant. Ex., Geology, p. 73. 



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