Vol. 70.] GLACIAL GEOLOGY OF EAST LAN T CASHIKE. 229 



Fig. 1. This indicates approximately the area covered by the ice-sheet when 

 at its greatest development. The ice-sheet extended beyond the 

 Pennine watershed, a large lobe crossing north of Boulsworth Hill 

 into Airedale ; and two smaller lobes, one crossing south of Black 

 Hameldon and the other east of Shore Moor, formed a combined 

 stream in Upper Calderdale. 

 2. At this stage, the ice had almost completely retreated west of the Pennine 

 watershed, except the lobe which (although steadily diminishing) 

 continued to enter Airedale throughout all the stages here depicted. 

 Lakes were held up by the ice-barrier, and their surplus waters were 

 discharged across the Pennines into Calderdale. The summit of 

 Winter Hill appeared above the ice- sheet. 



Figs. 3 & 4. A further retreat of the ice-barrier led to the production of large 

 lakes in the upper valleys of the Irwell and Roch, and of a smaller 

 series in the Babble basin, west of Boulsworth Hill and Black 

 Hameldon. Fig. 4 represents the critical stage, when the lakes in the 

 Irwell basin were about to cease from discharging into Calderdale. 



Fig. 5. The drainage of the Irwell- Mersey basin next escaped into the Trent 

 basin. The main outlet for the Kibble drainage was still by way of 

 the Yorkshire Calder. 

 6. The lakes in the Kibble basin next increased considerably in size, 

 and the whole of their surplus waters was discharged west of the 

 Kossendale highland into the Irwell-Mersey basin, and thence into the 

 Midlands. At this stage, the connexion between the main ice-sheet 

 and the southward- flowing lobe between Pendle and Boulsworth 

 Hills was severed. 



Discussion. 



Mr. R. H. Tiddeman wished to remind the Society that 

 this paper was a sequel, and in his opinion a very valuable sequel, to 

 a series of papers in the Society's Journal on the Grlaciation of the 

 North-West of England, which related to almost contiguous areas. 

 These were: — in 1872, by the speaker, 'On the Evidence for 

 the Ice-Sheet in North Lancashire & Parts of Westmoreland & 

 Yorkshire ' ; in 1874 & 1875, by Clifton Ward, ' On the Glaciation 

 of the Northern' & Southern Parts (respectively) of the Lake 

 District ' ; and in 1875, by J. G-. Goodchild, ' The Glacial Phenomena 

 of the Eden Valley & the Western Part of the Yorkshire Dale 

 District.' 



In the first paper the speaker had been irresistibly compelled by 

 the evidence in his ground to hold the view that the Scottish and 

 Lake-Country ice had held up the ice-drainage from North Lanca- 

 shire, and compelled its flow to the south over land. His further 

 conviction, deduced from facts by other observers, that the Irish Sea 

 had been occupied by an ice-sheet which overflowed the Isle of Man, 

 Anglesey, and the plains of Cheshire, was, he thought, now fully 

 admitted. 



The present paper so well worked out, illustrated, and presented, 

 was strongly confirmatory of those views. The existence of 

 overflow-channels discovered by the Author was very valuable, 

 and the speaker was now well aware of many similar occurrences in 

 his ground to the north, although they were not at the time 

 recognized as such. 



