1^56 Dr Giiby jun. on the Trap and Clay-slate 
as the ascent of a few feet brings us directly upon a sort of har- 
dened wacke. In walking from Llandegly rocks to Bettys, I 
found in one or two places the black shale at the foot of the 
range, and at Bettys, near a mill, there is a considerable quan- 
tity of it. The edges above Llandrindod Wells, is composed of 
greenstone and clinkstone, but about half a mile from the Wells . 
near the Bock-house, the black shale (if I remember right) is 
seen very extensively. I have found it in many other places, 
which it would be needless to mention, and which, in fact, it 
would be difficult to describe, from the want of names to fix 
their locality. I shall mention two other instances, in speaking 
of the junction of the trap with the clay-slate. This occur- 
rence, as I have before said, I only remarked in two places, one 
of which is in a quarry near Mr Thomas’s house of Pen Carig ; 
the other I observed in the bed of the river. In this quarry a 
great mass of greenstone is exposed, and on one side the clay- 
slate is seen resting on it, converted into a highly indurated 
rock. The exact relation which the trap maintains with the 
greenstone is not very evident, as the whole has a very confused 
appearance. Opposite to this quarry there is a gate, and after 
passing a little way through it, we come to a spot where an 
opening has been made in the rock, which is then the black 
schist described above ; and here, again, it is evident, that it 
must lie very near to the trap. 
The second instance where I met with the hardened clay- 
slate in contact with the greenstone, is in the bed of the river 
near Builth, about a mile up the river towards Bhyador. The 
spot cannot be missed, as the appearances which present them- 
selves are too interesting and extraordinary to be mistaken. 
We here see the river broken by projecting mounds of rock, 
whidi proceed from both sides of the river, sometimes opposed 
to each other, sometimes jutting out alternately. These ledges 
are for the most part trap, and every where traverse the slate, 
so that the intervals between them are filled up by the schist. 
This in fact is the precise point of the trap range above allud- 
ed to, where, having altered its direction to the west, it crosses 
the river before spending itself in the ground about Park Wells. 
I regret exceedingly that my incapacity for drawing should not 
have enabled me to give a representation of the scene which 
