576 MR. A. R. DWERRYHOUSE ON THE GLACIATION oF [ Aug. 1902, 
quantity of ice had considerably diminished. They do not form 
the limit of the Drift, but are seen to be followed by a more evenly 
distributed sheet of Drift which extends considerably higher on the 
hillsides, and was evidently produced at the period of maximum 
glaciation. 
The following is a description of these ridges, both as regards 
their distribution and probable origin, commencing at the source of 
the Tees. 
As already stated, the Tees rises in the neighbourhood of Cross 
Fell, and receives several tributaries from the semicircle of hills 
forming part of the Cross Fell Group. The headwaters of the Tees, 
together with these upper tributaries, occupy a basin-shaped hollow, 
the bottom of which is covered with mounds of Drift containing 
only such rocks as occur zn situ in this part of the Dale, namely :— 
Carboniferous Limestone and shales, sandstones and grits from 
the Limestone Series, and from the Millstone Grit, which forms 
the summits of several of the higher hills. 
I have not been able to find any basalt in the Drift of this part 
of the Dale, above the point where Troutbeck enters the Tees; but 
13 miles below that junction basalt occurs in situ in the bed of 
the river, and from this point onward it is a characteristic of the 
Drift. 
The sheet of Drift-material, which has been already mentioned as 
extending beyond the lateral moraines of the lower part of the 
valley, can also be seen in this upper portion, and at the head of the 
river it extends up to a height of 2000 feet above sea-level. 
From Troutbeck to Cauldron Snout there is not very much Drift 
exposed, the ground being thickly covered with peat. Here and 
there, however, mounds of Drift appear through the peaty covering, 
and Drift can also be seen in the beds of the tributary streams, 
again underlying the peat. The Drift is of the same general type 
as that higher up the stream, except that it contains a large 
quantity of basalt. 
On the western side of Herdship Fell the Drift extends up to 
the 1900-foot contour-line, and completely covers the col at Cow 
Green (4), between Herdship Fell and Widdybank Fell (5), being 
thus continuous with the Drift of Harwood Beck. 
There is little Drift on the east side of the river at Cauldron 
Snout, the rocks being very precipitous; but on the western bank 
there are several large mounds. Immediately below Cauldron Snout 
the Tees receives Maize Beck, and then enters the gorge between 
Widdybank Fell and Cronkley Scar. Here the Drift becomes 
decidedly more morainic in character, consisting largely of angular 
and subangular blocks of basalt and limestone. It is sometimes 
difficult to distinguish between the true Glacial deposits and the 
post-Glacial talus, in this part of the valley. 
On the summits of both Widdybank Fell and Cronkley Scar can 
be seen a number of boulders of basalt, resting on the surface of a 
saccharoidal limestone which is both higher in the series than the 
