646 REPORT— 1901. 



• 7. Rfjyort on the Terrestrial Surface Waves and Wave-like Surfaces. 



See Reports, p. 398. 



S, Report on the Exploration of Keish Caves, Co. SUgo. 

 ^ee Repqrts, p. 282. 



• ... 



9. Evidences of Aaicient Glacier-dammed Lakes in the Cheviots. 

 By Percy F. Kendall, F.G.S., and Herbert B. Muff, B.A., F.G.S. 



It is uncertain wlietlier tlie Cheviot .itself was overridden by extraneous ice, 

 but striae on Thirl Mooi* and Balier Cra<2; recoi-ded by the Geological Survey 

 probably indicate that this portion of the watershed was overridden by ice from 

 the Tweed Valley, and Prof. Geikie. mentions till and striated stones on the tops of 

 the Cheviot Hills at 1,500 ft. The transport of erratics shows movement along 

 both sides of the axis of the range from S.W. to N.E. at some stage of the 

 glaciation. Across the northern end and for at least ten miles down the eastern 

 side, however, a distribution of rocks from the Tweed Valley, together with other 

 indications to be mentioned, points to an ice-flow veering round through easterly 

 to a due north-to-south direction. The observations of the authors go to confirm 

 the above conclusions with respect to the area N. and E. of Cheviot. 



The authors, during a few days spent in the district, observed certain features 

 which throw much light on the later stages of the Ice Age in this area. Mr. 

 Clough mentions ' ' dry, steep-sided little valleys crossing over watersheds, which 

 do not appear to lie along lines of weakness or the outcrops of soft beds. It is 

 suggested that they might have been formed by streams from glaciers.' Some of 

 the valleys observed by us run along the sides of hills or occur as loops detaching 

 portions of the walls of valleys, and the general characters of similar valleys have 

 been described by us separately.- Their mode of occurrence and the relations to 

 the relief of the country, as well as to the position occupied by the ancient ice- 

 sheets, show that they can be ascribed only to the overflow of water from lakelet.s 

 held up by an ice-barrier. In the tract of country between Yeavering Bell and 

 Ino-ram we found that each of the spurs separating the valleys which radiate from 

 Cheviot was cut across by one or more sharp gorge-like channels, divaining, with 

 one significant exception, to the south. The spur between Roddam Dean and the 

 Breamish River is cut near Calder Farm by a channel, bounded on the east by 

 the moraine, draining to the south ; but a higher portion of the same spur is 

 traversed by a channel draining in the opposite direction, i.e., to the north. The 

 highest member of a series across any given spur is usually just above the boun- 

 dary of the drift containing extraneous boulders. At the outlets of the valleys 

 there are, in several cases, deltas represented by masses of gravel. 



Conclusions. — -The existence of the series of overflow channels points clearly to 

 the former presence of a chain of small lakes held in the radial system of valleys 

 of the Cheviots by a barrier of ice. The ice-stream by the boulders which it bore 

 may be inferred to have swept round the end of the Cheviots out of the Tweed 

 Valley. The margin of the sheet at its maximum extension rose to about 

 1,000 ft. along the arc from Yeavering Bell to Brand's Hill, beyond which it 

 may have declined. Along the south-eastern slopes of the Cheviots another 

 extraneous glacier swept in a north-east direction. Where their confluence took 

 place, or whether they were not in succession rather than simultaneous, is not 

 easy to decide, but the Roddam Burn channel points very clearly to the prepon- 

 derating influence of the southern stream, while the Calder Farm overflow lower 

 down the same ridge shows by its southerly slope that the northern ice later 

 acquired the mastery. If the two glaciers were confluent, then the overflowing 



' Oeol. SuTv. Mem., 'The Geology of the Cheviot Hills.' 



- B.A. Report, 1890, P. F. Kendall, ' On Extramorainic Drainage in East York- 

 shire ' ; \M(l., 1900, A. Jowett and H. B. Muff, 'Preliminary Note on the Glaciation 

 of the Bradford and Keighloy District.' 



