514 S. V. WOOD, JUN., Olf THE I^EWER 



out of a sea-bed which had been in existence throughout most of 

 Stage II., the gravel c has not yielded these remains ; and as none 

 of the remains from the gravels of the Severn system have come 

 from them at elevations great enough (when we take into account 

 the rise of its level from the westerly increment of submergence) to 

 correspond with c, or even with the gravel [e) over the Chalky Clay, 

 we may infer that they most probably, though not necessarily, belong 

 to the period embraced in the second part of this memoir. Their 

 character does not assist in this determination, for they differ in no 

 essential way from the shells at Moel Tryfaen and other places of 

 extreme elevation, all of which are those of MoUusca living now in 

 the eastern part of the IN'orth Atlantic, and comprise none of those 

 species which so clearly show the Bridlington and Dimlington beds 

 to belong to the earlier part of Stage II. 



Another subject also requiring notice before I proceed to the 

 examination of the morainic formation of Stage Y. is the absence 

 of drift on the eastern slope of the Pennine, south of the Aire, at 

 any altitude at all corresponding to that at which it occurs on the 

 western slope. This has been long known, and it forms the subject 

 of a special examination in the Geological-Survey memoir for 

 Sheets 81 E. and 71 S.E. "Where the Pennine is breached by the 

 vaUey of the Derwent in Sheet 81, and of the Calder in Sheet 88, 

 drift extends up those valleys to increasing heights westward*, 

 though not (so far as it would appear from the Survey memoir) to 

 heights so great as that at which the highest Macclesfield patch 

 occurs on the west slope , and, as I have already said, some sfJecial 

 set of the currents has been invoked for an explanation of the phe- 

 nomenon. On the other hand, near the line dividing Sheets 88 and 

 92, glacial drift is said to be present, and to rise to very great ele- 

 vations on the eastern slope, and so continue northwards f. It 

 is over this part, close to the division line of Sheets 97 and 102, 

 that the blocks of Shap granite have travelled from the western 

 slope of the Pennine and across the watershed. This transit has 

 occurred at elevations between 1400 and 1500 feet, if not, indeed, 

 somewhat higher ; and what is very important to observe is that 

 this transit has not occurred by several routes which traverse the 

 watershed at lower elevations than this, down to one as low as 

 800 feet. These routes all lie in Sheets 93 and 97, and are given 

 in detail in my paper on the Boulder-clay of the Worth of England 

 in the 26th vol. of the Journal, p. 109. In that paper (labouring 

 under the error as to the time of the great submergence) I attri-, 

 buted the passage of these blocks to the agency of floating ice at 

 the period of greatest submergence (a view which I no longer 

 entertain either as to agency or period), and suggested that the only 

 explanation of these blocks not having travelled by the lower routes, 

 that I could see, was that these routes were blocked by ice. In the 

 same paper I pointed out, as the fact is, that these blocks do not 

 occur in the Chalky Clay, but are confined to the Purple ; and under 



* Dakyns, Quart. Journ. Geol. Soc. vol. xxviii. p. 382. 



t Bakyns, loc. cit. See also Curry in Q.uart. Journ. Geol. Soc. vol. xxxiii. p. 40, 



