504 J. G. Goodchitd—On Drift. 



on the blending of the two currents, find their way into the body of 

 the conjoined stream without first working downwards to the base. 

 When once they were fairly into the ice, gravity would have but 

 little effect upon their position; but they might be floated, so to 

 speak, across wide valleys, or over lower currents, transporting 

 other boulders in different directions without working downwards 

 to any appreciable extent. 



The observations of Prof. J. D. Forbes, lately extended in the 

 paper by Mr. James Geikie, referred to above, would tend rather to 

 show, that instead of working down, any solids included in the body 

 of the ice would tend sooner or later to find their way to the surface, 

 through the wasting of the upper parts of the ice under the influence 

 of the sun, warm ^air, and rain ; while its general level was kept 

 constant by accretions from the various feeders of the trunk stream. 

 Prof. Forbes and Mr. Geikie consider that the boulders might 

 work up to the surface of the ice in this way from any part of the 

 bottom ; and, after reading Mr. Geikie's paper, I am inclined to 

 think that the filling of the ice-sheet with stones and mud, in the 

 ways that I have suggested, may have been quite subordinate to the 

 combined action of ablation and turgesence, treated of by the authors 

 just named. 



What it is particularly wished to call attention to here is the fact 

 that the direction of transportal of boulders is very often at right 

 angles, and in a few cases is directly opposite to the course taken by 

 the sole of the ice-sheet, as indicated by the glaciation of the rock 

 surface, or by the direction in which other boulders have travelled. 



Thus, the glaciation of the Isle of Man has been shown to have 

 been from the north-east, or from the mountains of the Lake District; 

 while the course taken by the boulders has been from the north, 

 north-east, and perhaps also from the north-west. 



Another case is that of the glaciation of the ground about Lan- 

 caster, which Mr. Tiddeman has shown to have been, generally 

 speaking, from north to south, while the course taken hj the boulders 

 from the western part of the Lake District and from Scotland lies in 

 a south-easterly direction. 



Again, the boulders from Galloway have travelled eastwards 

 towards Newcastle ; south-eastwards up the valley of the Eden, and 

 thence over Stainmoor to the Vale of York ; and, southwards, skirting 

 the high ground of the Lake District as far as Eavenglass, whence 

 their course was south-easterly, to near Manchester, and thence south- 

 wards to an unknown distance. 



On the other hand, boulders have radiated far in nearly every 

 direction from every mass of high land, often in courses exactly 

 opposite to those taken by the extraneous drift, with which, locally, 

 they may happen to be associated. 



Thus Prof. Sedgwick has mentioned the occurrence of boulders 

 from the Lake District in those parts of Galloway which have 

 furnished the greatest number of erratics to the Lake District itself. 



Even in those parts of the Lake District in which the majority of 

 the boulders have moved outwards at low levels, we find that some 



