151 
14. The large fallen masses rising out of the lake in front of the 
cliffs occupy positions indicating a more powerful undermining cause 
than any form of fresh- water agency which could ever have existed in 
this small vaUey. 
15. At the south-west end of the lake, the cliff-line has been deeply 
indented by an exceedingly picturesque winding creek, the greater part 
of which must have been scooped out by an agency capable of acting on 
level ground. This creek presents an intensely sea-coast aspect. 
16. Between the lake and the Harrogate road, one may see a nearly 
square aperture, about four feet in diameter, and from fifteen to twenty 
feet long, the roof, floor, and sides of which show that it has not been 
left by weathering, but by the abstraction of fragments or blocks. 
Near it a rounded large stone may be seen in a joint. In this Uttle- 
visited part of the Plumptou grounds, the continuously peiyendicular 
cliffs rise above, and extend below the surface of the talus in a way 
demonstrating that the talus has not resulted from the decay of the 
cliffs, and that the cliffs must have existed before the talus began to 
accumulate. In this neighbourhood there is a cave with a rocky floor 
longitudinally level, so that rain could not have washed out detritus ; 
and the rock composing its sides is too hard to be abraded by wind, 
supposing it to be accessible to wind, which is rather doubtful. 
General Kemarks. 
Among the Plumpton Eocks, but especially towards the south end, 
the impression cannot be resisted that, where the weather acts, it is on 
previously-existing cliffs which the weather could not have formed. 
The weather here is a modifier, or rather a destroyer — certainly not an 
originator. 
As regards mere rain, it ought to be recollected that the most char- 
acteristic features of the Plumpton Rocks are to a great extent protected 
from its action, and that rain-drops, on pervious gritstone, sandstone, 
and sand, have very little abrading power. Where the summit-area of 
a rocky stack is adapted to coUect rain-water and concentrate it into 
minute runlets — where these runlets become charged with a little loose 
surface-grit — where they fall over the brink of a cliff, and meet at some 
distance below, with projecting masses of rock, they wear out vertical 
furrows in these masses, as may be seen near the south end of the lake. 
But while there are a few instances of these vertical furrows among the 
Plumpton Eocks, they are evidently a super-imposed form of surface 
configuration quite distinct from the typical shape of the rock surfaces, 
which must therefore have been produced by a different cause. 
The undercutting or undermining of the Plumptou Eocks has, on a 
small scale, often followed the structure of the rocks, and been directed 
