256 . The Irish Naturalist. [Oct., 



Upham in America ; but should not Mr. J. G. Goodchild also ap- 

 pear prominently in this connexion ? Mr. Goodchild (i) put forward 

 in 1874 the somewhat curious view that drumlins and eskers accumulated 

 on rock-bosses and rock-ridges bet-ween the channels of subglacial streams, 

 i.e., between the channels of greatest flow ; but, if he did not indepen- 

 dently proceed precisely on Hummel's lines of argument, his papers 

 contain much that is strikingly original, and much that appears to 

 anticipate the work of Hoist. Had he been more familiar with Irish 

 eskers, his theory would doubtless have widened, and he would have no 

 longer demanded a rocky boss as a base for every accumulation. His 

 papers contain consistent and valuable explanations of the form and 

 inner structures 'of drift-mounds, as well as the suggestion that the 

 occasional contortions are due to the settling down of ice-blocks in the 

 glacier-mass (2). Prof. Sollas, after his review of the literature, gives a 

 topographical account of the principal esker-systems in the area selected 

 by him, showing how each "presents a remarkable resemblance to a 

 map of a river-system. The narrow linear outlines, the meandering 

 course, the branches converging like tributaries, or diverging like the 

 channels of a delta, the loops and knots are singularly alike in each " 

 (p. 817). He ranges himself as an adherent of Hummel's view rather 

 than that of Hoist, the materials of the esker having "been deposited 

 on the place where they are now found by the action of running water," 

 and not " precipitated in mass from the bottom of sinking ice-canons " 

 (p. 819). The striking observations of Russell on the Malaspina glacier 

 certainly afford the strongest support to the subglacial rather than the 

 englacial theory. Where eskers run across the general direction of 

 glacial striae in the district, their origin is somewhat boldly at- 

 tributed to crevasses, at the base of which the gravel is held to 

 accumulate. 



Certainly, when we see an esker, like those in the romantic district 

 west of Cookstown, running up and down across a valley, with the air 

 of the Great Wall of China, and breached at right angles by the stream, 

 we feel that we have still a good deal to learn. But Prof. Sollas has done 

 for Ireland what has been done for parts of eastern America and 

 Scandinavia, and has given us a comprehensive view which raises pro- 

 bability a long way towards proof. The map is beautifully printed, in 

 four colours and a groundwork, and two portions are given in the text 

 on a larger scale. There is also a " fig. 3," apparently showing the re- 

 lation of eskers to lines of bog ; but to this we have been unable to 

 find a reference. As we have already hinted, the treatment of the sub- 

 ject in the text is even more important than the map ; and the 

 paper becomes a permanent work of reference upon eskers. 



G. A. J. G. 



(1) " On Drift." Geol. Mag., 1874, pp. 509 and 510. Also "The glacial 

 phenomena of the Eden Valley, &c." [Read June 24, 1874]. Qjtart./otcrn. 

 Geol. Soc. London, vol. xxxi. (1875), p. 95. 



(-) Geol. Ma§. 1874, p- 508, and Q.J. Geol. Soc, vol. xxxi., p. 96. 



