530 MR. P. F, KENDALL ON A SYSTEM OF [Aug. 1902, 
uncertainty may be found here, is entirely absent from the next 
case to be described. 
About a mile below Crunkley Gill, the steep hillside on the south 
of Eskdale is ex- 
Fig. 20.—Map and section of Sunny-Brake _ cavated byavery 
Slack ‘in-and-out.’ perfect example 
of an ‘in-and- 
out’ channel. 
Sunny - Brake 
Slack, the chan- 
nel in question, 
is about 75 feet 
deep, with sharp- 
ly cut sides and 
a broad peaty 
floor falling to 
the eastward. 
The excavation 
was commenced 
above the 475- 
foot contour, and 
it cuts through 
HM 200' O.D. 
the 425 nearly to 
the 4002 icor 
contour. 
The main Esk 
Valley here de- 
Scale, Ltt te yy Yea seends to 275 
feet, and at the 
+75-foot contour it is three-quarters of a mile wide, so that it will 
hardly be believed that the post-Glacial denudation could have 
achieved all this; but besides this, it 1s not the habit of rivers to 
forsake a rock-gorge on account of the difficulty of cutting in it. 
The levels show, I think, that the ice-barriers stood simultaneously 
here and at the gap in the Lealholm moraine, for the cutting 
commenced at Sunny Brake at a level above. that at which the 
Lealholm gap would have been open. Between Crunkley Gill 
and Sunny Brake a narrow marginal lake probably extended, 
much of it more river than lake; and at several places scarping is 
observable, especially in the fields south of Low-Wood Lane, 
where there is a very pronounced feature between the 450- and 
475-foot contours. 
A third significant gorge occurs at Glaisdale, less than half a mile 
below Sunny Brake. Here the Esk has cut a deep gorge into the 
rock to evade a morainic obstruction, although the moraine is of less 
height (325 feet O.D.) than the top of the gorge, which is distant 
only 300 yards. (See map, Pl. XXIV.) 
Other rock-gorges, always, as Mr. Barrow has remarked, on the 
south side of the valley, may be seen at East Arncliffe and Bank 
Wood, but their testimony is not decisive. They may be due merely 
