COAL NEAR CORWEN, NORTH WALES. 453 



transportation of debris may at times have taken place in a direction 

 almost diametrically opposite to that of the glaciation of a district. 

 But it would not be difficult to bring forward many instances in the 

 north-west of England and Wales, of the interweaving of drifts from 

 points of the compass ranging from 90° to even 180°. This inter- 

 weaving, however, is generally of very limited extent. 



Postscript. — Since this paper was written I have unexpectedly 

 had occasion to visit the Corwen district a second time. I reexa- 

 mined the coal-beds in the railway north of Corwen, and in the 

 fine gravelly matrix of one of them found a considerable variety of 

 rock-specimens, in this respect differing from the coarser gravel I 

 had previously observed. The gravel, in all probability, was partly 

 worked up out of the underlying or adjacent Boulder- drift : but such 

 could not have been the case with the angular lumps of coal ; for, 

 while the waves would have rounded them or reduced them to 

 powder, no trace of coal (so far as I am aware) has yet been found 

 in the Boulder-drift. A little north of this spot, Mr. Jones, toll- 

 house keeper, has lately found coal in still greater abundance. 



