474 MR. K. M. DEELEY ON THE PLEISTOCENE 



nth. The present atmospheric agencies are not forming, but are 

 destroying such deposits. 



12th. The major axes of the pebbles frequently coincide with the 

 trend of the furrows and ridges. 



All these physical peculiarities point to ice, glacier ice, as the 

 agency to which they owe their existence. In some few cases the 

 contortions appear to have been formed by the neve which collected 

 on the hills before the cold conditions finally passed away. 



As mentioned before, there is nothing to prove that the deposits I 

 shall describe in this stage might not have been formed during more 

 than one interval of cold occurring while the deposition of the Inter- 

 glacial River-gravels took place. If such had been the case the 

 morainic clays thus formed at different periods would be too much 

 alike, both as regards lithological character and mode of occurrence, 

 to be now distinguishable the one from the other. 



That such a widespread deposit should be generally so thin, and 

 that the ice which formed it should have accomplished such a 

 moderate amount of work, judging by the deposits it has left behind 

 it, as compared with some of the earlier glaciers, will perhaps be 

 urged against my contention that this was a period of great cold and 

 confluent glaciers. Its comparative thinness may be accounted for 

 by the fact that, where I have seen it in the Trent basin, the deposit 

 is either wholly subglacial or subaerial. Some geologists have even 

 gone so far as to argue that no deposits whatever of Boulder-clay 

 are ever formed beneath ice-sheets, their action being considered 

 entirely erosive. On the other hand, others have adopted an equally 

 extreme view both as regards their aqueous and subglacial origin. 

 The truth probably lies somewhere between these extremes, and it may 

 be that instead of the subglacial moraine being entirely mythical, it 

 more frequently occurs as a moderately thin Boulder-clay similar to 

 the one now to be dealt with. 



In Staffordshire the Later Pennine Boulder-clay contains Pennine, 

 Cumbrian, and even Cambrian erratics ; while in Nottinghamshire 

 and Derbyshire the boulders are almost wholly either of Pennine or 

 local origin. South of these counties it is generally more scantily 

 developed. I shall therefore first notice its mode of occurrence in 

 Staffordshire, then trace it through Derbyshire and Nottinghamshire 

 and finally south into Leicestershire. 



Mr. D. Mackintosh describes several Staffordshire sections of 

 Boulder-clay. At one time he was inclined to believe that they 

 belonged to a later stage than the Chalky Clay ; but in a recent 

 paper they are regarded as its westerly continuation. Por many 

 reasons I am inclined to believe that his early view was the more 

 correct. 



In Wolverhampton itself there are several exposures. In these 

 sections the deposit, which is of no great thickness, consists of local 

 rock, very much broken and disturbed, together with pebbles and 

 boulders of distant origin. 



West of the Cemetery it is worked to a depth of five or six feet. 

 Here and there it contains intruded masses of sand, and, in addition 



