DRIFTS OF THE YALE OF CLWYD. 



75 



shoulders of Arenig and pointed to the east. Down into the 

 valley of the Dee between Corwen and Bala ; up the steep slope 

 of the Berwyns, as shown by the east and west striae south of Xant- 

 caweddau ; hill after hill bears traces of the passage of the ice in 

 that direction. There must have been some barrier on the north, 

 perhaps the foot of a great ice-sheet from Scotland and the Lake3, 

 so that the Welsh ice crushed its way eastward over hill and dale, 

 ignoring all the highest ranges in its course, down into the Vale of 

 Clwyd, scoring the limestone rocks at Cefn, as seen in' the road- 

 cutting behind the stable-yard ; then up over the high hills form- 

 ing the northern end of the Clwydian Range, as seen on the top of 

 the hill S.E. of Cwm ; across the Hope Mountain and Alinera : all 

 the striations running roughly east. Xo icebergs coming from the 

 west can have grounded behind Cefn. All the evidence points to 

 land-ice as the agent to which we must refer these striae on the 

 solid rock. 



Along the Clwydian Range huge blocks of the volcanic rocks of 

 Arenig are common. A group is seen by the cottages above the 

 Grove near Bodfari. One enormous boulder lies at the junction of 

 the highest mountain-fences X. vV\ of Moel Fammau. 



The more northern portion of the drift, derived from the Sno^don 

 rather than the Arenig area, might perhaps be distinguished. There 

 seems to be a difference between the older drift near the north coast 

 and that a little further south ; but all comes from the west. 



The western drift, I think, is seen in the deep sections which the 

 Elwy has cut into the hill-sides above Dolben, and especially at the 

 bend in the river near Dol, where landslips have, however, some- 

 what complicated the section, bringing down some newer drifts 

 which lay upon it higher up the slope. 



One section gave the following succession : — 



Pig. 1. — Diagram-Section seen at bend of River Elwy, near Dol. 



c. Reddish boulder-clay, resting, "with a very irregular line of junction, on d. 

 (Northern or St. Asaph drift.) 



d. Blue-grey boulder-clay. (Western Drift.) 



The newer drifts rest with a very irregular line of junction on an 



