BY HUGH MILLER. 333 



It is surprising to find, however, that only some details of 

 their form have been moulded by glacier erosion. Greatly pro- 

 tracted and of immense geological importance as the glacial period 

 undoubtedly was, it is astonishing that these escarpments have 

 not been planed down and levelled. But this is certainly not the 

 case. "We occasionally find their crest bevelled off and their 

 brow rounded, but the curve is a steep one ; and I have again 

 and again traced the uppermost stratum of their dipslopes to 

 within a few feet of the scarp before it began to thin away to 

 any appreciable extent. 



In order to bring these facts fully into light I cannot do better 

 than select one representative crag in some pre-eminently ex- 

 posed situation. JN'o better representative could probably be 

 found than the curious crag, interesting in many ways, which 

 projects its great black prow along the eastern bank of the Korth 

 Tyne below Gunnerton. From the direction of the glacial strias 

 in the Gunner Mck, close beside this crag, it is proved that the 

 last movement of the ice was fair against its scarp. There is no 

 positive reason to doubt that the Gunnerton Crag breasted the 

 valley-glacier during the whole of the actively glacial period. 

 But allowing for the possibility that during the height of the Ice- 

 age, the sheet of ice, which passed athwart the valley in an east- 

 erly direction, occupied ITorth Tynedale to the exclusion of the 

 local glacier, a glance at the sketch will show what an obstacle 

 the crag presented from that approach. (Woodcut I^To. 8.) 



This crag is also especially suitable because its elevated posi- 

 tion has enabled it to retain its talus undisturbed. Quarrying 

 operations have opened large sections of the interior, presenting 

 clear evidence of this fact. The large outer blocks, which 

 falling furthest by reason of their weight had formed a bul- 

 wark to protect the more promiscuous debris within from the 

 inroads of streams — scarce likely ever to have been near (see 

 the outline sketch), and certainly not in such volume as to move 

 blocks as large as the largest stepping-stones in the river, had 

 evidently remained unshifted since they fell ; and as for the 

 oifects of granular disintegration, the angular form of small 

 fragments in its deepest and oldest part shewed how insignificant 



