088 MR. A. R. DWERRYHOUSE ON THE GLACIATION oF [ Aug. 1902, 
channels, now quite dry, and running parallel to the edge of the 
cliff. The most marked is that of the group of rocks known as The 
Castles, at High Holwick (fig. 5, p.586). In this case the water 
from the edge of the ice has cut a channel, about 100 feet deep and 
possessing an average width of 50 yards at the top, thus severing 
The Castles from the main mass of the escarpment. 
The large size of this channel, as compared with some of the 
other gorges in similar situations farther down the valley, is to be 
accounted for by the fact that this upper channel must, at that 
stage, have taken the whole drainage of the country around Howden 
Moss and Bleabeck Grains, in addition to the water from the side of 
the ice in the neighbourhood of Cronkley Scar. The spur above 
Gill Brae is severed by a channel known as the Hind Gate, which 
is now dry, and evidently belongs to the same drainage-system. 
The upper end of the Hind Gate opens into the Gill Gate, a normal 
drainage-channel, at a height of 30 feet above the bottom of the 
latter, and ends downward in a gulley of the basalt-cliff at a 
height of 1150 feet above sea-level. 
Fig. 6.—Section near West Crossthwaite (Teesdale). 
bo 
= Carboniferous Limestone. j= sipaee -Clay. 
= Whin Sill. 4 = Dry valley. 
Another excellent example of a channel of this description is 
that on the edge of the cliffs immediately above the sheepfold at 
West Crossthwaite. It is a channel cutting off a spur, and com- 
mences at its upper end in the side of a normal gulley, which is at 
this point 40 feet deeper than the dry valley (fig. 6). The bottom 
of the channel is full of peat, and there is now no stream, nor is 
there, under existing conditions, any possible catchment for such 
a stream. This channel is continued on the opposite side of the 
gulley, but it is not so well marked there. 
Thus, during the period of retreat, there was an interval of con- 
siderable duration, during which the level of the ice remained 
constant both in Teesdale and in Lunedale. . The cause of this 
stable interval during the final retreat of the ice I am unable even 
to guess at, at the present time; but Mr. P. F. Kendall informs me 
that he has met, in the Cleveland district, with evidence pointing in 
the same direction. After this period of constant level the ice 
seems to have dwindled very rapidly, as there are no terminal 
