Hugh Miller — Escarpments and Terraces. 27 



15 feet above it glacial drift is indicated. A few yards further east 

 the escarpment, though gapped at its maximum height, has sunk com- 

 pletely down, the feature being merged in a peat-moss, the surface of 

 which, padded out by vegetable accumulation as it is, is yet con- 

 siderably below the summit of the gap. The stream had thus only 

 to flow on a little further to obtain a course unimpeded. It is 

 necessary to add that this gap, unlike the great majority, is traversed 

 by a fault of some 15 feet throw ; but agreement will probably sub- 

 sist between glacialists and sub-aerialists that a closed or nearly 

 closed fault, crossed at right angles by a glacier, could offer no 

 vantage for the excision of a narrow notch. That the point of weak- 

 ness should have been chosen when the escarpment was in its in- 

 fancy explains everything. 



Passing down with the stream, we find it borne along the base of 

 the next escarpment for fully a mile contrary to its destination, when 

 it doubles through another gap. This it is necessary to describe 

 somewhat more accurately. The feature crossed is of a compound 

 character, and no fault exists. From the middle point of a line drawn 

 across the forefront of the gap to the end of the dip-slope at the 

 further side is a distance of 280 yards, and rather more than 100 

 yards within the former an exposed face of 'till' of the usual type 

 (with scratched stones partly local, partly of western origin) slopes 

 up from the water's edge. About 25 yards further in, rock is seen 

 on both sides, and the breadth of the gap determined thereby at 50 — 

 60 yards from brow to brow, the slope of the banks varying from 

 30" to 23°. That this is a pre-glacial gap in an escarpment demon- 

 strated as also pre-glacial is a fact which admits of no doubt. 

 Glacial markings — nearly coinciding with the trend of this and 

 other escarpments — occur just half a mile distant, and nothing 

 intervenes to modify the line of motion there indicated. Neither — • 

 I must add — does the gap present coomb-like features ; it is a simple 

 notch rasped out by pre-glacial stream-action, in the shelter of which 

 — while glaciers swept over and by it — debris lodged. 



Passing on j^et again, we are carried half a mile nearly parallel 

 but contrary to the westward deflection terminated as just described, 

 and then find the stream deviating to slide through a third gap. 

 This presents mainly the features which the other two have in 

 common. The point chosen, however, is that of a local deterioration 

 in the bedding of a sandstone which advances and rises on either 

 hand into crags. The gap thus terminates a wide angle, into which 

 the dip-slope of the inferior bed thrusts itself like the point of a 

 broad knife towards its sheath. Of this I will only say : 1st, a 

 glacier would have left not an angle but a curve ; 2nd, the stream 

 was not compelled to cross here ; and 3rd, there is nothing to show 

 that its course was ever obstructed previous to forcing a passage.^ 



The course of the Crook Burn — aptly so named — is nearly along 



^ Exceptional cases occur in which sucli ponding did take place. ^ In these the 

 waterflow found itself barred by accumulations or intercepted by basins, neither of 

 which existed before the Glacial Period. 



