THE VALE OF CLWYD. 21 
to bottom. It is a soft, false-bedded sandstone, of a red brown, 
or brownish red colour.” (See also Ramsay Mem. Geol. Survey, 
Vol. iii., p. 228.) The quartz grains are only coated with the 
iron oxide, but this is not easily removed altogether, as may be 
seen by the red colour of the drift sand derived from it. When, 
however, the colouring matter is destroyed by chemical action, 
the sand is found to consist of grains of pure white quartz, much 
of it being clear. 
We have at the base of the New Red the second great 
geological break in our district. Just as, in speaking of the base 
of the Carboniferous, we had to point out that the Silurian Rocks, 
and a great series, the Lower Old Red, which regularly and 
conformably succeeded them, were upheaved, and all the higher 
ground was washed away by rain and rivers, and perhaps frost 
and ice, and the sea cut back the cliffs, and planed off the ancient 
continent, and then the land went down again, and the 
Carboniferous Rocks were formed in a gradually sinking area, 
where: silting up nearly kept pace with submergence, so that 
sometimes we get a filled-up estuary with drifted wood and fresh 
or brackish water shells, and at other times find that the sea has 
rushed in with its brachiopods and even corals. So now we have 
to tell exactly the same story over again; the Carboniferous 
Beds, and the still more ancient rocks which formed the floor 
on which they lay, were all lifted up, and the rain and rivers, 
and frost and ice and sea, again began their work, in places 
even stripping the Carboniferous away, and exposing the old 
Silurian, much, if not all of which had been covered up by the 
newer deposits. Again there was dry land over our district. 
What was that old land-surface like? As before, we get for 
answer that there is very little can be made out about it. 
Perhaps we may notice that we have more evidence of 
limited hydrographical areas at the commencement of the 
New Red than during the early part of the Upper Old Red 
Epoch. We find at the base of both traces of valleys and of 
subaerial waste, but at the base of the Upper Old Red, or 
Devonian, we find more evidence of marine denudation as 
well. In both cases we find in some other areas tremendous 
banks of shingle marking the shore of an encroaching sea. 
But in our district, although we are on the edge of a mountain 
land, it is curious how often we find that there is little or 
no conglomerate at the base of the New or of the Old Red 
along lines of what must once have been shore. I think the 
explanation of that may be that the part now exposed is some 
Way up the ancient mountain slopes, and that the conglomerate 
has got drifted further down into hollows. ° 
It is a noteworthy circumstance that when the Mountain 
Limestone rests on the older rocks, without the intervention 
of the Upper Old Red, corals are seen growing on the boulders 
that lay scattered on the sea bottom. So when the calcareous 
Cc 
