102 Professor P. F. Kendall — The English Eskers. 



Gregory has recently revisited the district. What has he new to 

 say of the crescents ? The one passing through York is included in 

 the general description as " Glacial sands and gravels " without 

 qualification, yet Dakyns, Clark, Fox Strangways, and Carvill Lewis 

 describe it as consisting principally of boulder-clay ranging up to 

 a thickness of 70 feet ; and there has been for many years in the 

 railway cutting that completely intersects the ridge near Ploltby 

 an exposure showing nothing but boulder-clay, with a few wisps 

 of sand. 



The description of the southern ridge Professor Gregory, apparently 

 on second thoughts, qualifies by the sentence quoted above, though 

 without any confirmation from his own observation. In fact, this 

 ridge, where traversed by a light railway near Wheldrake, showed an 

 extraordinary tangle of boulder-clay with loops and pockets of sand 

 and gravel, and a bore-hole at a farm-house on the summit of the 

 ridge proved exactly 100 feet of boulder-clay. A similar appearance 

 near Escrick Station is described by Dr. Parsons. 



The description of the contours of the southern ridge are very 

 misleadingly described by the omission of any reference to the fact 

 that, like its northern fellow, it protrudes through a great mantle 

 of so-called " Warp " clay, and thus both its height and the contour 

 of its flanks are concealed. 



The agency which, according to Professor Gregory, produced 

 this pair of parallel crescents is discoverable only by the implication 

 of his remark that the southern one " appears to be a rise left by 

 denudation ", leaving it to be assumed that the northern one of 

 similar structure is also residual. 



How this denudation was effected and by what agency, no 

 suggestion is vouchsafed. Professor Bonney's naive comparison 

 with '"ordinary hills of sand and gravel" is no more helpful. One 

 might as well dismiss the geology of the Matterhorn with the remark 

 that it was " an ordinary mountain of schists ". 



Professor Gregory derives some comfort, apparently, from the 

 fact that Mr, J. E. Clark " favours their [the drifts] deposition by 

 floating ice ", but that solitary piece of consolation should have 

 been put in the past tense, for Mr. Clark's candid and alert mind 

 promptly recognized the applicability of the morainic hypothesis, 

 and he frankly admitted twenty-five years ago that this 

 explanation was preferable, so Professor Gregory is left with but a 

 single supporter. 



I am well aware that scientific questions are not settled by a 

 count of votes, but the competency and experience of the voters 

 should carry some weight, and I can cite among upholders of 

 Dakyns' morainic hypothesis, apart from British observers not a 

 a few, five American geologists, four of whom could each be credited 

 with the mapping of hundreds of miles of moraine in the North 

 American continent ; they are Lewis, Wright, Upham, Leverett, 

 and W. M. Davis. 



