94 J. G. GOODCHILD ON THE GLACIAL PHENOMENA OF THE 



the later period, all traces of the former existence of the great ice- 

 sheet must have been obliterated from the low ground. Every- 

 where the ice appears as if, after it had reached its maximum 

 thickness, it had quietly melted away, without the lower part, at 

 any stage of its liquefaction, ever again advancing over the rock. 



Another point that many recent authors seem agreed upon, but 

 that is not so well borne out by the facts observed in the district 

 treated of in this paper, is that the till is largely, perhaps almost 

 entirely, made up of detritus scraped from the rocky bed over which 

 the ice was passing — that the till was brought into existence under- 

 neath the ice, and there it was kept until the ice melted. 



Prof. Kamsay's theory of Glacial currents enables us to go a step 

 further than this in treating of the origin of drift deposits. 



"We can see that one of the results of such crossing currents 

 would be that streams of ice from subsidiary valleys would fre- 

 quently keep the level at which they blended with the main stream 

 for some distance from the valley wherein the lesser stream ori- 

 ginated, and that, in the numerous cases in which the upper parts 

 of the ice filling a valley were crossing it at various angles accord- 

 ing to local circumstances, much of the debris from the lee side of 

 the valley would be swept into the traversed current and transported 

 to the main stream, where these lateral moraines would be inter- 

 mingled with others derived in a similar way from rocks afar off. 

 What was there to cause the bottom layers, or, indeed, any part of 

 a tributary ice-stream, to pass at once into the lowest part of the 

 main stream, which in no small number of cases must have been 

 flowing in quite a different direction from that of its feeder ? Take 

 the case, for instance, of the local ice coming from the Cross-Fell 

 district to join the Eden-valley stream. The directions taken by the 

 main stream and its affluents must have often approached a right 

 angle ; and the level at which the local ice blended with the larger 

 stream must often have been several hundred, or even, in some cases, 

 a thousand feet above the bottom of the Eden-valley ice. The be- 

 haviour of no modern glacier would warrant us in concluding that, 

 in this and the innumerable similar cases that might be cited, the 

 high-level ice, with its load of boulders, would at once, or at all, 

 work down to the bottom of the main stream. 



It would be easy to point to many similar cases where the direc- 

 tion of the higher glaciation was often at considerable angles with 

 that of the adjoining lower ice over which it would pass. 



In this way it is quite possible that boulders might be transported 

 across wide valleys without ever reaching the bottom of the ice there, 

 so that the transport of Shap-granite boulders is not difficult to 

 understand when the existence of a great uptravelling mass of ice is 

 clearly proved. 



The frequent deflections of each stratum caused by the inflowing 

 of large feeders and the varying form of the rocky bed and the sides 

 of the valley along which the ice was passing, must have contributed 

 in a great degree to that intermingling of boulders derived from 

 widely parted sources that is one of the most noticeable phenomena 



