75 



is as stiff as it was before, as I know from having frequently cut 

 through it in old mine workings. 



The courses taken by some of the boulders in the lower clay, 

 whilst travelling from their parent rock, are shewn in Fig. ii. The 

 different currents by which the boulder-bearing bergs were swept 

 along, probably came into existence at different stages of submer- 

 gence. With a subsidence of nine hundred feet, there would be 

 a water passage from the southern part of the Lake District through 

 by Dunmail Raise and St. John's Vale, to the northern part of that 

 district. A northward current through this strait would carry with 

 it bergs laden with Armboth- and St. John's Quartz-Felsite, which, 

 subject to the effect" of other influences, might turn towards either 

 Keswick or Penrith, or through by Mosedale to Caldbeck, where 

 the operation of other currents might change their course and 

 carry them through the Tyne Valley, or southward along the 

 western foot of the hilly ground by Maryport, Whitehaven, and 

 Ravenglass, on into Furness. A further submergence of seven 

 hundred feet would form a water passage over Stainmoor, Thus 

 an explanation is forthcoming of the occurrence of Lake District 

 boulders in that locality. 



If now it be assumed that there was a gradual submergence of 

 the district under consideration at the time that the Lower Boulder 

 Clay was formed, there is at hand a complete explanation of all 

 the facts hitherto observed in the district. For then the glaciers 

 would gradually recede, and icebergs from other localities would 

 float over and drop their contents on to ground that was but 

 recently occupied by those glaciers, and so produce the observed 

 mingling of boulders from sources sometimes lying in very different 

 directions from the point at which they are enveloped in the clay. 



Origin of the Middle Sands and Gravels. The Middle Sands 

 and Gravels may have resulted partly from the action of the sea 

 on the Lower Boulder Clay during a period of gradual emergence, 

 and partly from the action of rivers and streams. The angularity 

 of many of the stones in the gravel and the coarseness of some of 

 the sand being probably due in a great measure to the comparative 



