518 A. C. RAMSAY AND J. GEIKIE ON 



angular fragments over the precipices and cliffs. In further proof 

 of this we may point to the frequently brecciated aspect of the 

 limestone itself. In many places that rock looks as if it had been 

 smashed up in situ, the broken fragments having been subsequently 

 consolidated by infiltration. This appearance is especially conspi- 

 cuous between Middle Hill and the Signal Station. So broken is 

 the limestone thereabout that Mr. Smith thought this betokened the 

 presence of a fault. But the beds may be traced continuously 

 across the " broken " area ; while further down the western slope, 

 and precisely in the line of the supposed fault, the rock ceases to 

 show a broken aspect. The same broken or brecciated appearance, 

 moreover, is conspicuous in many other places in different parts of 

 the Rock, and it is hard to see what power other than frost could 

 have so ruptured the beds. 



Of course no excessive degree of cold is necessary for the forma- 

 tion of rude debris at the base of a lofty cliff. Indeed, even under 

 present conditions, stones and occasional larger blocks must some- 

 times be dislodged and rolled down the precipices ; and, given 

 sufficient time, these will gradually accumulate and become agglu- 

 tinated into a breccia or agglomerate. But the old weathered and 

 worn aspect of the agglomerates shows that these accumulations 

 do not owe their origin to present conditions ; and, as we have 

 already indicated, the position which many of them occupy points 

 still more strongly to the same conclusion. But something more 

 than the mere action of strong frost is needed to account for the 

 presence of the wide-spread and massive agglomerate of Rosia and 

 Buena Yista. Supposing we admit that the large angular blocks 

 with which the agglomerate is charged even down to the present 

 water's edge were detached from the top of the limestone ridge, we 

 have yet to explain the mode of their transportation. It is quite 

 clear that they could not have merely rolled to their present position. 

 A glance at Section IV. will show that from O'Hara's Tower to the 

 Upper Road, a distance of 600 yards or so, the ground slopes at an 

 angle of 35° as near as may be. That is not too great an angle for 

 the repose of debris ; and were the agglomerate at present under 

 consideration a formation now going on, we should find it hard 

 indeed to account for the fact that no curtain of debris is being 

 formed upon that slope at present, while the indurated debris or 

 agglomerate which must have been derived from this very declivity 

 only begins to come on in force upon the gentler slopes yielded by the 

 shales. Nor can we believe that the agglomerate in question 

 originated quite in the same way as the debris on hill-sides in our 

 own country. It is quite impossible to believe that large blocks 

 and smaller fragments, even supposing they had been set in motion 

 from the very top of the ridge at O'Hara's Tower, could yet acquire 

 sufficient momentum to carry them across the whole breadth of the 

 gentler slopes at the base of the Rock, a distance of 550 yards at 

 least, over which the average inclination of the ground is not more 

 than 8° or 9°*. Nor will winter torrents better account for the 

 phenomena. No gathering of water can take place upon such a 

 * In some places the slope does not exceed 2° or 3°. 



