TRANSACTIONS OF SECTION C. 431 



8 — Basal Visean — (C, + Sj of old notation). 



The ' N.W. Channel ' overspread a wide area, including the Yoredale 

 country N.W. of the Faults (Ingleboro'j &c.) and the whole of South Lanca- 

 shire; it commenced to climb the north coast of 'Wales,' reaching the neigh- 

 bourhood of Llangollen. 



The ' S.W. Channel ' retreated from the Clee Hill embayment to such an 

 extent that the new shore-line ran just north of the Forest of Dean. 



S— Middle Visean. 



Deposition commenced in the ' N.W. Channel ' over the Midland Area of 

 Derbyshire, &c., and extended southward to Leicester (deduced from the shallow- 

 water indications of the basal dolomites). 



D,D2 — Upper Visean. 



The ' N.W. Channel ' climbed further up the north coast of ' Wales ' so 

 that the shore-line ran straight from Anglesey, through Oswestry, to the Wrekin. 



The ' S.W. Channel ' retreated still further southward, so that its shore-line 

 ran just north of Bristol and continued in a straight line to Pembroke. 



Notes. 



The ' Barrier,' which formed the land-crest between the two channels during 

 Visean time, had a dominant trend from Anglesey to Dudley ; it was never 

 submerged throughout the Avonian period, so that the S.W. Province was only 

 connected with the Northern and Midland Provinces round the Irish coast of 

 'Wales.' 



The whole neck of land which contained the ' Barrier ' and separated the 

 two ' channels ' shifted steadily southward as Visean time proceeded, owing to 

 the advance of the sea on the north of ' Wales ' and its retreat on the south. 



The remarkable similarity of the Visean sequence in the N.W. and S.W. 

 Provinces (compare Shap or Arnside with Bristol or Mendip) indicates free 

 communication of the two channels round the western or Irish front of ' Wales," 

 aided by great similarity of the northern margins of the ' N.W.' and 'S.W. 

 Channels.' 



The western or Irish coast of ' Wales ' probably shifted but little during 

 tire period, for just N. of Dublin (Rush, Malahide, &c.) the sea remained per- 

 sistently coastal (as shown- by the conglomerates, dolomites, &c.). 



7. A Preliminary Note on the Glacial Geology of the Western Slopes of 

 the Southern Pennines. By Albert Jowett, D.Sc., F.G.S. 



The 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 moi'e detailed information as to 

 the movements of the ice-sheet, the only evidence is that afforded by the dis- 

 tribution of the drift at high-levels and by the systems of drainage alcng the 

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

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

 roughly towards the north-east in the Tame valley, the east in the Etherow 

 valley, and the south-east and south-south-east in the Goyt valley and further 

 south. These directions were much modified locally by the complicated con- 

 figuration 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 the erratics generally 



