DRIFTS OP THE VALE OF CLWYD. 



83 



all similarly studded over with pebbles, which have stuck to the 

 moistened, softened outside of the clay-balls as they rolled along. 



At the time of the formation of the St. Asaph Drift the nearest 

 cliffs of boulder- clay were the masses of western land-ice drift, in 

 which the material was all from the west. All the scratched stones 

 were out of that, and therefore from the west. There were other cliffs 

 of boulder-clay to the north and east, from which northern boulders 

 fell into the sea and drifted along the shore ; but the pebbles from 

 them had a long journey by all sorts of conveyances before they 

 reached the Yale of Clwyd and their glacial polish and grooving was 

 all worn away. 



Of course, the distinction founded upon the occurrence of north- 

 country granites and flint is only local. The north-country land- ice 

 drift contains the granites and other rocks of that country striated, 

 and the older boulder- clays of the east of England are full of flints 

 and other chalk debris. But in the Yale of Clwyd these occur in the 

 newer marine drifts only. 



We are not, however, dependent on such evidence alone to prove 

 that these deposits are the result of the action of the sea. Shells are 

 not uncommon. They are generally fragmentary, it is true, just like 

 the shells thrown up in the sand and gravel of the North Welsh coast 

 to-day ; but they are, many of them at least, determinable, and I 

 have made a small collection in the river-banks described above, close 

 to St. Asaph. 



They were originally determined for me by the late Searles Wood, 

 and have been since seen by many good authorities. The list I have 

 given in column I. in the table, p. 93. 



So the evidence goes to show that here we have a marine deposit 

 much like that which is being formed in many places on the North 

 Welsh coast at the present time, where banks of drift and clay of 

 various age are being wasted by the waves. There seems to be no 

 necessity for supposing that glacial conditions still prevailed. The 

 forms of life are not Arctic. None of the stones peculiar to the deposit 

 are glaciated ; only those derived from the Welsh hills are striated, 

 and they were probably washed out of the old Arenig ice-drift. 



If it is asked, how, then, did the boulders from the north get trans- 

 ported to the Yale of Clwyd ? I would reply that many may have 

 travelled south on ice when the northern ice abutted against the ice- 

 bound shore of North AY ales, but they were not then carried into the 

 Yale of Clwyd. They came there and along the coast with the shore- 

 shingle, as did the flints, which cannot have come from the same 

 country as the granites. We may expect to find, somewhere further 

 north, patches of the old north- country boulder- clay with the granite 

 blocks in it scored by ice. But when they and the flints were tra- 

 velling along the shore as shingle all the original striae were removed. 



In following the Arenig Drift to the margin of the Cheshire plains 

 we are, of course, tracing it to what may have been always, and must 

 have been for a long time, its extreme limit. Therefore it is not 

 strange to find that there is a larger proportion of northern forms 

 among the shells found in the drifts of Cheshire and Lancashire. 



g2 



