SOUTH LAiS^CASHIRE, CHESHIRE, AND THE WELSH BOEDER. 379 



which are plentifully distributed over the liills up to a height of 

 nearly 1900 feet *. Though so many boulders of Flintshire lime- 

 stone have been scattered over the Millstone Grit, I know of no 

 instance in which they have travelled westwards on to the Wenlock- 

 Shale area. One boulder of limestone has been noted on Moel 

 Dywyll, at a height of about 1500 feet above the sea, but may be 

 reasonably inferred to have been derived from the Carboniferous 

 Limestone of the Vale of Clwyd. The vast majority of the erratic 

 blocks have been derived from the felspathic igneous series of the 

 Snowdon and Arenig range, while a large proportion of the remainder 

 are attributable to the Denbighshire Grits. 



The Carboniferous basement-beds, which form a narrow fringe on 

 the south side of the limestone escarpment of Llandulas and 

 Abergele, provide clear evidence of the direction of transport in this 

 neighbourhood, inasmuch as the colour and lithological character of 

 the pebbles of which they are composed renders them easily 

 distinguishable from any other local rock. These pebbles are found 

 to have travelled from the outcrop to the beach between K.hyl and 

 Colwyn, that is in a northerly or north-easterly direction. 



A less marked instance occurs in the case of Bryn Eurian, an 

 isolated hill of limestone on the west side of Colwyn Bay. The 

 proportion of limestone boulders in the local Boulder-clay of the 

 beach (the basement-clay) shows a marked increase at a point 

 bearing jST.^.E. from this hill. In the valley of the Dulas also it 

 may be noted that though no limestone boulders have travelled on 

 to the Wenlock- Shale area, yet the drift in the limestone gorge, as 

 far north as Eoel-fach, is composed exclusively of fragments of 

 Wenlock Shale. Still further to the north, in this gorge, this 

 AVenlock-Shale drift passes into a drift composed principally of 

 limestone boulders, but containing some northern derivatives. 



It would seem, from what has been said above, that the local drift 

 of the country adjoining the north coast of Wales has travelled 

 generally from the land towards the sea. The same remark, however, 

 would not apply to the drift of Flintshire. In this part of North 

 Wales the direction of transport was not towards the sea, though all 

 the physical features of the ground run in such a direction as would 

 appear likely to turn it in this direction, but was nearly at right 

 angles to and across the principal ranges and valleys, namely the 

 Moel Fammau range, the Millstone grit and Carboniferous-lime- 

 stone escarpments, the Yale of Clwyd, and the Vale of Llanarmon. 

 The fact of the transport having been towards the sea on the north 

 coast, would seem to have been merely a geographical accident, the 

 direction having been uniform along the whole border towards the 

 east-north-east, and in other parts of the district independent of the 

 physical configuration of the ground. 



I have previously described the boundaries of the drift of northern 

 derivation, and for the sake of clearness have indicated them by a 

 dotted line on the accompanying map (p. 370). There is a tendency 



* Mackintosh, Quart. Journ. Geol. Soc. xxxv. p. 425 (1879). 



