yy) NOTES ON THE GEOLOGY OF 
beds of the Jurassic group rest on the older rocks, without the 
New Red, they are highly fossiliferous. When, however, the 
Upper Old Red, which is the basement series of the Carbon- 
iferous, rests on the Silurian and pre-Silurian land, we find 
hardly a trace of life; and so when the New Red, which is the 
basement series of the Jurassic, rests on the Carboniferous and 
pre-Carboniferous rocks, we have the same absence of evidence 
as to the life of the epoch. We know that queer fish swam in 
the waters in which the irony deposits of the Old Red were 
thrown down, and we know that queer reptiles, like enormous 
toads, walked on the shores of the waters in which the some- 
what similar beds of the New Red were formed. But how 
little else we know of the life of either period, and in our 
district we have collected as yet hardly any evidence at all. 
Sometime after that our mountain land came up again. 
Whether it was rising during the long period when the Jurassic 
Rocks were being formed in the sea that washed its eastern 
shore, or whether the movement of upheaval took place chiefly 
in that time of known disturbance, when the Neocomian and 
Cretaceous sea advanced over the denuded edges of the 
Jurassic beds ; whether some tributaries of the Wealden river 
brought sediment down Welsh valleys; whether some of the 
lumps of coal found in the chalk may have come from Ruabon ; 
whether the igneous, metamorphic, and Silurian Rocks found in 
the Lower and Upper Greensand may have been carried from 
the mountains of Wales, or from ancient ridges now covered up 
or still exposed elsewhere, we have not at present internal or 
external evidence enough to show. We have not in our district, 
nor among the Welsh hills anywhere, any deposit of oolitic, 
cretaceous, or of any later date, until we come to that wonderful 
time known as the Glacial Period. Just beyond the mountains 
of North Wales, on the southern borders of our district, there 
is a small patch of Lias, to which the attention of the Society 
has been called by PRor. Jupp. So also near Cardiff, in South 
Wales, we have a small patch of Lias, with the passage beds 
from it down into the New Red. Just enough in both cases to 
remind us that we have in the New Red only the conformable 
basement beds of the Jurassic. 
The character of the New Red may be well examined in a 
quarry by the Clwyd, below Llanerch, and in various sections 
near Ruthin. The base is rarely seen. In the narrow valley 
behind Llanrhaiadr it seems probable that we must be very near 
it, but faults obscure the section. 
In the bed of the stream which runs down by Pontcerrig and 
Pentse, from Rhydganol, the junction of New Red and Silurian 
is seen in places to be a fault, but on the upthrow side some 
New Red seems to be still left resting on the Silurian. The 
Silurian is much decomposed, and deeply stained red and purple. 
The decomposition splits it up along the mica layers, so that it 
sometimes looks like a flaky Devonian. 
