part 2] MODE OF TRANSPORTATION BY ICE. 73 



The presence of thin lenticles of shelly drift intercalated between 



beds of boulder-clay is another anomaly that is quite easily ex- 

 plained in this way ; in fact, the same occurrence is observed at 

 Cape Royds, where the marine muds disappear under a covering of 

 normal moraine in one place. 



The association of different forms of shells, rock, sand, and mud- 

 loving species all in the same drift, is naturally explained, for 

 the bottom muds from different places are ultimately all collected 

 on the upper surface and would be laid down together. 



The classic shell-beds of Moel Tryfaen defy complete explanation 

 from this very character as well as from their great height above 

 sea-level. Edward Forbes described them as 



' a confused mixture of fragments of species from all depths, both littoral and 

 such as invariably live at a depth of many fathoms .... Deep and shallow- 

 water species mingled could at no time have lived together, or have been 

 thrown upon one shore.' l 



It is quite possible for the ice-sheet to have frozen to different 

 depths at different times and places, the muds from which would 

 finally find the same level on the surface of the sheet and be de- 

 posited together. Rearrangement by fluvio-glacial action might 

 then leave them as they now appear. The difficulty of their great 

 height above sea-level (1100 feet) does not appear to me to be 

 necessarily due wholly to elevation since the Glacial Period. The 

 Great Hoss Barrier in one place mounts overland to a height of 

 1200 feet above its normal level close to its seaward edge, and 

 there seems reason to believe that it rises to a height of 1800 feet 

 on its eastern side where it abuts on Edward VII. Land. 



But it must be left to those who know the shelly drifts well to 

 apply the theory, and to judge whether the same conditions as 

 those now found in the Antarctic may not be postulated for the 

 sheets of waterborne ice that invaded these islands in the Glacial 

 Period. 



EXPLANATION OF PLATE IV. 



Fig. 1. The northern side of the Ferrar Glacier at H (on the map, fig. 1, 

 p. 52). The marine mud is found on the low hillock in the fore- 

 ground, as well as on the pinnacles behind. 

 2. Mounds of sponges and polyzoa on the Lower Koettlitz Glacier at F 

 (on the map, fig. 1, p. 52). 



Discussion. 



The President (Mr. G. W. La.mpltjgh), in thanking the Author 

 for his paper, said that it was of peculiar interest in bringing out 

 clearly the extensive scale on which marine material could be taken 

 up from the sea-floor into an ice-sheet. Such material would after- 

 wards necessarily be transported as far as the ice travelled. In the 



1 Mem. Geol. Surv. vol. i (1846) p. 384. 



