78 



PROF. T. M'KENNY HUGHES ON THE 



predominate, may be seen in the beautifully clear view of the 

 Greenland ice given in the Report of the Danish Commission 

 (Meddelelser om Gronland, Heft 1 : Copenhagen, 1879). 



What is a well-established generalization from the examination 

 of the drifts of Eastern England, and bears upon the question now 

 before us, is that there are along the eastern coasts two quite distinct 

 stages — an earlier stage, in which there is more evidence of the 

 direct action of ice, though the deposits are marine like those of 

 later date, and these older drifts contain an Arctic fauna ; and a 

 later stage, also marine, resembling the boulder-clay from which it 

 is chiefly derived, but containing few northern forms of life and no 

 evidence of glacial conditions prevailing near. 



See also : — 



Seaeles Wood. Quart. Journ. Geol. Soc. vol. xxxvi. 1880, p. 516 ; 

 vol. xxxviii. 1882, p. 707. 



Gelkie, J. ' The Great Ice Age,' 1877, pp. 366-381 ; ' Prehistoric 

 Europe/ 1881, p. 264. 



Seaeles Wood. Geol. Mag. dec. 2, vol. v. p. 15. 



A type of the older drift with Arctic shells, perhaps the marine 

 equivalent of the Arenig drift, may, I think, be seen at Dimlington 

 and Bridlington (see references below, pp. 91, 92). 



Other examples might be quoted, for instance the Arctic shells 

 found by Brown in the drift at Elie, in Eife, and Errol, in Perth, 

 which, according to Otto Torell, were the same as those now living 

 in front of the Great Glacier at Spitsbergen. (Brown, Rev. Thos., 

 Trans. P. Soc. Edinb. vol. xxiv. p. 627.) 



In such investigations we are continually met by the great diffi- 

 culty of determining whether a drift is not re-made in some way or 

 another, and -whether scratched stones and shells may not have been 

 derived from older deposits. (See also, Kinahan, Geol. Mag. dec. 2, 

 vol. i. " Glaeialoid or Re-arranged Drift ; " Mellard Reade, Proc. 

 Liverpool Geol. Soc. 1873-74, p. 50, " Tidal Action as a Geological 

 Cause/') 



Some have suggested that the shell-bearing drifts of North Wales 

 represent portions of the sea-bottom thrust forward by the ice-foot 

 and pushed up the flanks of the mountains till, on the melting of 

 the ice, they settled down where they now lie. There seems to be 

 no doubt that such transport of frozen masses uphill and the coming 

 to the surface of matter in glacier-ice does occur. It is analogous 

 to the travelling of boulders across valleys and uphill in glacier-ice, 

 as suggested years ago by Mr. Goodchild in explanation of some of 

 the phenomena of the Lake-district (Geol. Mag. dec. 2, vol. ii. 1874 ; 

 Quart. Journ. Geol. Soc. vol. xxxi. 1875, p. 55), and more generally 

 by Prof. James Geikie (Trans. Geol. Soc. Glasgow, vol. iv. 1874, 

 p. 235, in the ' Scottish Naturalist,' and in his paper " On the Inter- 

 crossing of Erratics "). Professor Carvill Lewis refers the shell- 

 bearing deposits of North Wales to the terminal moraine of a mass 

 of land-ice, which carried granite from Scotland and shells and flint 

 from the bed of the Irish Sea (Brit. Assoc. 1886 ; Geol. Mag. dec. 3, 

 vol. iv. 1887, p. 29). I think, perhaps, he would make an exception 



