GEOLOGICAL OBSERVATIONS 



of the Ferrar Glacier, as well as to the south-east of 

 Mount Larsen. 



The first locahty on Ross Island was discovered by 

 Armytage; the second locality by one of us; the raised 

 beaches near the Ferrar Glacier also by one of us; while 

 the Mount Larsen raised beaches were observed by the 

 Northern Party on their journey to the South Magnetic 

 Pole. These four localities may be referred to as: 



(1) Back Door Bay deposit. 



(2) Cape Barne deposit. 



(3) Ferrar Glacier deposit. 



(4) Mount Larsen deposit. 



Deposit (1) lies at a height of 160 ft. above sea-level. 

 It was found at the bottom of a shallow flat-bottomed 

 guUey sloping down eastwards into a small arm of 

 McMurdo's Sound, called by us Back Door Bay. The 

 area of the deposit was only a few square yards. It con- 

 sisted of a brownish earthy material with abundant remains 

 of crushed tubes of serpul^. Diatoms were fairly abun- 

 dant in it. We were at first in some doubt as to whether 

 this serpula deposit was a genuine raised beach, or merely 

 a mass of sandy material from the sea floor pushed up by 

 the ploughing action of the old McMurdo Sound ice sheet. 

 There has, of course, been a similar question raised in re- 

 gard to the so-called raised beaches of Moel Tryfaen in 

 North Wales. The subsequent discovery by one of us of 

 an extensive raised beach at an altitude of about 180 ft. 

 near Cape Barne (deposit 2) is confirmatory evidence 

 as to the genuine raised beach character of the first- 

 mentioned deposit. At this Cape Barne deposit the mate- 

 rial is largely formed of spicules of siliceous sponges and 

 molluscan shells, as well as the remains of serpulee. The 

 nature of the organisms there present is such as to render 



317 



