468 Notices of Memoirs — Glacial Geology of S. Pennines. 



characteristic of the Upper Tournaisian of Bristol, but possibly 

 extending into the base of the Yisean, are cited in the Castleton list, 

 Michelinia glomerata being fairly abundant at Peakshill, and 

 Amplexus coralloides is found at Treak Cliff, but is extremely rare. 



These facts lead to a consideration as to how far the types 

 mentioned are of value in zonal determinations. If any one of them, 

 as recorded from Castleton, be regarded as representing exactly the 

 same form as that recorded from the Bristol area, then its value as 

 one of a number of index fossils of a zone becomes negligible. 

 Examples are cited in the cases of Spiriferina octoplicata and 

 Schizophoria resupinata. If the Castleton forms of D 2 horizon agree 

 in identity with the Bristol types of K 2 and Z2 respectively, then 

 these two types become worthless as sub-zonal indices. It was 

 pointed out that, even allowing of the rather unlikely possibility that 

 in all the cases cited the Castleton specimens represented mutational 

 forms of the Bristol species, the real difficulty as to their zonal value 

 is not overcome, since the line of demarcation between mutations is 

 more or less arbitrary, and there is still a considerable field of 

 discussion as to what constitutes a ' mutation '. 



It appears probable that any system of zonal indices can be of local 

 value only, as for example in the application of the Bristol zonal 

 indices within the Bristol area, and cannot be of any general 

 application. 



(3) A Preliminary Note on the Glacial Geologt of the Western 

 Slopes of the Southern Pennines. By Albert Jowett, 

 D.Sc, F.G.S. 

 TpHE area dealt with extends from Blackstone Edge southwards to 

 _|_ the southern extremity of the Pennines. 



No striated surfaces of solid rock have been discovered at high 

 levels, and the two that have been recorded at Salford and Fallowfield 

 serve only to indicate a general movement from N.W. to S.E. For 

 more detailed information as to the movements of the ice-sheet, the 

 only evidence is that afforded by the distribution of the drift at high 

 levels and by the systems of drainage along the edge of the ice. 

 From this it may be inferred that the main directions of ice move- 

 ment about the time of the maximum extension of the ice-sheet were 

 roughly towards the north-east in the Tame Yalley, the east in the 

 Etherow Yalley, and the south-east and south-south-east in the Goyt 

 Yalley and further south. These directions were much modified 

 locally by the complicated configuration of the sub-glacial surface. 



The first barrier of hills met with on approaching the Pennines 

 from the South Lancashire and Cheshire plain was almost everywhere 

 overridden by ice, which left definite deposits of drift with foreign 

 rocks at altitudes up to 1,360 feet, and scattered erratic boulders up 

 to 1,400 feet. As this foreign drift penetrates further into the hills 

 its maximum altitude falls steadily. It has only been traced across 

 the main Pennine divide at the broad col (1,100 feet above O.D.) 

 south-east of Chapel-en-le-Frith. 



Thick deposits of drift and big erratics are comparatively rarely 

 met with at the extreme limit of the foreign drift, towards which 



