236 Correspondence — P. F. Kendall. 



One more confession I must make. The lithographer who twenty- 

 eight years ago transferred the Drift details from the map of the 

 Geological Survey to illustrate my paper on the York Moraines 

 did, to gain some private end, omit a pink spot one millimetre in 

 breadth and I failed to detect the omission and so incur the awful 

 penalty. Why Professor Gregory attaches any importance to it 

 J fail to see. The rest of his criticisms of my remarks on the 

 phenomena about York so ingeniously evade the real issue that 

 rather than weary the readers of the Geological Magazine with 

 their discussion I will ask those who are interested to compare 

 Professor Gregory's original statement with my comments and his 

 rejoinder. 



I may remark that though I adhere to my early opinion that the 

 Fulford-Escrick ridge is an esker (using the word in a generic 

 sense), its precise mode of formation demands careful investigation, 

 especially in view of the occurrence of Mammalian remains in or 

 beneath the gravel. 



I must now revert to the Lanshaw Delves and their interpretation,, 

 for here are exemplified those characteristics of Professor Gregory's 

 glacial work that, in my judgment, outweigh all the good that 

 might conceivably be found in parts of it. 



It will conduce to an understanding of the case if we suppose that 

 Professor Gregory ascended the steep moorland path from Ilkley 

 Station (300-6 O.D.), keeping in mind Carvill Lewis's description of 

 the Lanshaw Delves and the signs of old lime-kilns, and the 

 description in the Geol. Surv. Memoir of the ridges " composed of 

 limestone-boulders mixed with pebbles and sand," ..." They lie 

 partly on Boulder Clay and partly on ground free from this 

 deposit." 



He finds it to consist of " sandy loam with many angular blocks 

 of Millstone Grit similar to those strewn over the adjacent moors. . . 

 The smaller pebbles include vein quartz and jagged fragments of 

 black chert; and all these may have been derived from the Mill- 

 stone Grit ". His inference follows that this was the remains of 

 a moraine of " an embryo corrie glacier ". " The depression between, 

 the summit and the Delves faced N.E. and was probably filled with a 

 sheet of snow and ice." The reason for coming to this conclusion in 

 preference to Carvill Lewis's view that it was the lateral moraine 

 of a great glacier filling the valley of the Wharfe to this altitude 

 (about 1,180 feet) is given by implication in a passage that I must 

 ()uote at length. 



" The high-level eskers south of Tlkley are said in the Survey Memoir 

 to rest partly on boulder clay, but I saw nothing to confirm this 

 statement regarding Lanshaw Delves or any erratics, boulder clay, 

 or other trace on the moor of any general glaciation of the district. 

 The surface is littered with blocks of grit formed by weathering in 

 situ. Even at the level of 600 feet in a quarry at Eldwick, on the 

 southern side of the moor, the deep decomposition of the sandstones. 



