THE DALES OF DERBYSHIRE. 53 
pursued both courses, and thus by its chemical action, and 
also by its mechanical force, excavated the passage we 
know as Matlock Gorge to-day. The waters of this lake 
having disappeared in consequence of the barriers being 
pierced. 
We can continue our consideration to the point, where 
the Wye falls into the Derwent. As the dales of the 
large valley are the most interesting in the Shire for 
the purpose of shewing the influence of water in the for- 
mation of the dales, we will consider Lathkil Dale. In 
this dale a condition of things is to be observed, which 
will give us great assistance in acquiring a broad idea of 
the subject of dale formation. At the entrance there is the 
same condition of affairs as in Matlock Dale. The water 
which excavated the passage is still occupied with the same 
task. The barrier at the entrance to this dale is only 
partially, though certainly in greater part, cut through, the 
water being backed up to form a small lake, which is 
gradually deepening its bed by wearing away and dissolving 
the rock below. As we proceed, the shallow pools, in which 
we see boulders of the grey rock cropping up on every 
hand, intensify the idea that we are looking upon the 
remains of a once great lake. The sides of the channel 
_are composed of the same grey rock in a more or less 
horizontal position, and if the strata at either side are 
compared, we must conclude, as I have previously pointed 
out, that they were once continuous, in other words, the 
the evidence is that the dale was worn out or excavated 
by the agency of water. Passing onward the water is 
confined in a narrow bed, and as we near its source, the 
sides of the passage approach closer and closer together 
until we reach the spot where the water gushes out of the 
solid rock. Lathkil Dale therefore may be styled the type 
of a complete Dale. We have the end barrier still in 
process of being worn away, the water partially dammed 
