296 TYNEDALK ESCARPMENTS; 



The pebble in the rivulet, with its eddying hollow in front and 

 its little tail of sand sheltered behind, seemed to him the counter- 

 part of the *' ironf rented " rock, stemming the rush of waters 

 with a slope of strata and debris in its lea. Modern geology as- 

 cribes the debris and scored rocks to a deluge, not of water, but 

 of ice ; but it has been content, in points not a few, to confij*m 

 Sir James' observations. It is interesting to note that it was at 

 Gilsland, not far fi'om the Crag-and-Tail this paper deals with, 

 that an important point in his theory suggested itself to him. 

 Low in the valley of the South Tyne, he remarked an absence of 

 Crag-and-Tail, and having noticed the same elsewhere on the 

 west, he bethought himself of a * ' back-cb'aught " of water, that 

 failing in its easterly rush to reach the summit level of the country, 

 fell back by its own weight and smoothed away the scars its first 

 sweep had made. 



"When the fact of a glacial period had come into recognition, an 

 ocean-stream laden with icebergs, took for a time the place of the 

 mythical deluge- wave. That this view of the Crag-and-Tail of 

 Edinburgh still retains supporters I gather, somewhat doubtfully, 

 from Mr. Milne Home's " Estuary of the Forth."* It is happily 

 not necessary to enter here into tlie question of icebergs versus 

 glaciers. Since the grounding and dragging of ice-floats in the 

 supposed circumstances could only abrade the protuberances that 

 might arrest them, — as Mr. Milne Home seems to recognise, the 

 current, not the ice, must be the scooping agent. The possibili- 

 ties of escarpment formation by the sea will be considered fm-ther 

 on. 



2. Thcorii of ProiniHion.] — Although between the Tynes the 

 nature of the outcrops, — regular almost as the sloping bars of a Ve- 

 netian blind, precludes any idea of vertical upheaval of the crags, 

 it must be admitted as possible that certain applications of sub- 

 terraneous force might cause one bed to advance or retreat upon 

 another, somewhat as the pieces of a telescope, with their ledge- 

 like profile, slide out or in. This theoiy was, so far as I know, 



• TliP Kstuary of tho Forth and iidjolning districts viewed gooloifically. 1871. 



t Tlili name wlU Mrve to dvslgiiato for the nonce a theory, that so far as I am aware, 

 bat not )>ccn diatlngulshrd liy nny. To l>o fully de»criptlvc, It should be lengthened into 

 Throviinf l'ri4niiion or Witfuhniral. 



