190 J. AITKEN ON THE DRIFT OF THE PENNINE CHAIN. 



Clough from the White well valley at an elevation of 1170 feet, and 

 passing on east of Deerplay Hill and the high land adjoining into 

 the valley of the Irwell, thence skirting the hilly district east of 

 Bacup and crossing Brandwood Moor, the dividing line between 

 the basin of the Roach and Irwell, and so continuing its course 

 on to Manchester and the great Cheshire plain; whilst another 

 stream of ice would doubtless cross from Burnley into the Whitewell 

 valley by the Wholaw-Nook pass, becoming there confluent with the 

 arm already described, the main body moving off in the direction 

 of Burnley and Accrington, on the westerly side of Hambledon Hill, 

 thence pursuing its course south and uniting with the other streams, 

 finally debouching onto the plains of South Lancashire. 



In support of the theory that a large body of moving ice meeting 

 with resistance sufficiently powerful can be either entirely arrested, 

 or its various portions be endowed with varying and diverse motions, 

 we have the authority of the Duke of Argyll, Prof.. Ramsay, and 

 Mr. Goodchild, some of whose statements fully justify the conclusion 

 that such was the behaviour of the ice in this instance. 



In all probability ice did not overflow the higher hills in this part 

 of the axial range, as is manifested by the absence of all trace of 

 its action upon the surface-contour of the country, and by the fact 

 that there are no remains of morainic or other matter to indicate 

 that it had ever been in those situations. 



It may be assumed that the great ice-sheet in this part of Lan- 

 cashire did not rise to so great an elevation by some hundreds of 

 feet as it is proved to have done further to the north by the obser- 

 vations of Mr. Tiddeman, Mr. J. Clifton Ward, and Mr. Goodchild ; 

 and I contend that satisfactory reasons may be given for this vari- 

 ation by taking into consideration the gradual slope of the ground, 

 the waste by melting to which the ice would be subjected in tra- 

 velling south, and its tendency to spread out and become diffused 

 on reaching the flatter and more level plains of Lancashire and 

 Cheshire. 



Statements contained in the memoir by A. H. Green, C. Le Neve 

 Foster, and J. R. Dakyns on the Geology of the Carboniferous Lime- 

 stone, Yoredale Rocks, and Millstone Grit of North Derbyshire and 

 the adjoining parts of Yorkshire, confirm many of these conclusions 

 arrived at by me on independent grounds. 



I have thus endeavoured to lay before the reader such facts as 

 have come within my reach tending to illustrate the question forming 

 the subject of this essay, with what success he will be able to judge. 

 If, however, the facts and arguments should fail to carry conviction, 

 I trust that the effort I have made to solve this somewhat difficult 

 and perplexing question may not prove altogether fruitless ; for 

 should no other result follow than that of attracting the attention 

 of other observers to the subject, so that eventually a satisfactory 

 solution may be arrived at, my object will, at all events to some ex- 

 tent, have been attained. 



