FormatloJt in Brecknochsliire. 257 
-here presents itself, as it is almost impossible to write a faithful 
description of it. 
It would be tedious and useless to enter into a particular ac- 
count of the number and composition of the different ledges of 
rock, and of the various appearances observable at each. I shall 
therefore content myself with giving the following remarks. 
The first thing which strikes the attention, is the hardening 
of the clay-slate almost every where, at its union with the green- 
stone ; I say almost every where, for at one spot (I think the 
fourth ledge) the soft bituminous slate lies immediately upon 
the greenstone. The induration of the clay-slate is seen v^y 
beautifully at the first of these projecting ledgeg* of rock, 
where the greenstone is flanked on both sides by^ a complete 
flinty slate, so that the slate lies over the trap like the roof of 
a house. It is worthy of remark, however, that there is no dis- 
tinct line of separation between the schist and the trap ; on the 
contrary, there is a gradual passing of the greenstone into the 
hardened slate, and it is also curious that the slate^ or rather 
the flinty rock, at its actual union with the trap, is not strati- 
fied, the stratification being manifest only when a little removed 
from the greenstone. The dip of the slate is every thing that 
js perplexing ; sometimes it lies in a conformable manner upon 
fhe trap, sometimes it appears to dip under the ledge, as is the 
case at a tongue of rock, (a little above the island in the middle 
of the stream,) where the slate on one side is dipping under, 
and on the other side stands quite perpendicular. In other 
places, the slate seems shattered and turned about in every di^ 
rection, and several times I observed large patches of the indu- 
rated schist completely contained in the greenstone. At the first 
tongue of rock there is an example of this sort, and also oppo- 
site the island on the Parkwell side of the river. In several 
places we observe the clay -slate, as it were, squeezed into tlie 
trap, and vice versa. 
The effect produced by the greenstone in indurating the clay- 
slate, does not extend very far, as it is evident that the space 
between the ledges into which the water flows, has been origi- 
“ These, and the following remarks, refer chiefly to that side of the river ad- 
joining the Rhyador rOad ; and by the first ledge, 1 of course mean the nearest to 
Euilth. 
