THE DENUDATIONS OF NORTH WALES. 41 
to the Ludlow, but in colour resemble the Old Red Sandstone, 
and are therefore known as the Passage Beds, including the 
Tilestones. These are overlain by the vast thickness of red 
sandstone of which the Brecon Vans are composed. In Westmor- 
land the Ludlow rocks and the Tilestones are clearly recognisable, 
as before stated. Inasmuch as these rocks do not occur i” sifu 
in North Wales, we must look for evidence of their former 
existence in some other form. 
About three or four years ago Mr. Watxer called my atten- 
tion to some remarkable pebbles which were to be found on the 
beach near Llandulas, and stated that he had seen some of the 
same kind in a lane about a couple of miles inland. Eventually 
Ffernant dingle was pointed out to us, where the pebbles were 
seen to occur in a conglomerate, obviously forming part of the 
Carboniferous Basement Beds. The pebbles were of large size, 
and in great abundance. Their flattish shape indicated that 
they had been derived from a rock that split readily into slabs, 
and their rounded corners indicated that they had been well 
water-worn, and had probably travelled some little distance. 
On breaking them we vubserved that they were of a purple 
softish sandstone, highly micaceous and fissile, and frequently 
fossiliferous. The character of both the stone and the fossils 
was unmistakable. The pebbles were in fact the remains of 
the missing Tilestones. I do not know that we should have 
ever followed up this interesting search, if it had not been for 
the assistance most unselfishly given us by one to whom, I believe, 
most of us are more or less indebted—I mean Mr. Price. He 
many years ago observed these pebbles and pointed out the 
dingle in which they occurred to Mr. Bowman, who described 
the section before the Geological Society of London under the 
title of ‘A small patch of Silurian, West of Abergele.’* 
Though we could not agree with all Mr. Bowman’s conclusions, 
especially in his naming the conglomerate as Silurian, yet it 
was a pleasure to confirm the accuracy of his work as we 
traversed the ground, and it is a pleasure now to testify to the 
merits of work done nearly 45 years ago, when geology was in 
its infancy. My only regret is that Mr. Price did not himself 
bring forward his own observations, the result of years of 
patient and shrewd observation. 
Time would not permit me now to enter into all the inferences 
we drew from this section. It is sufficient to say that the 
oceurrence of pebbles of purple sandstone ix such abundance 
led us to believe that the Ludlow or Tilestones must exist in 
places under the Carboniferous at no great distance; while from 
the absence of fragments of Wenlock Shale or Lower Silurian 
Beds we argued that the drift of the pebbles could not have 
been from the North-west, West, South, or South-east, for in 
* Geological Transactions, Vol. vi., Part I. See also “On the occurrence of Pebbles 
with the Upper Ludlow Fossils in the Lower Carboniferous Conglomerates of 
Rorih Wales,” by A. Strahan and A. O. Walker. Quart. Journ, Geol. Soc., 
May, 1879. 
