416 Dr. E. Greenly — 



would, at the cave's door, slope inward also. Snow, gathering in 

 drifts, would mix with it, begin to slide, and when thaw came would 

 make the gliding of the scree-bank into the cave quite an easy matter. 

 With the sliding of the talus, any skeletons of animals who had 

 sheltered and died at the crag's foot would be disintegrated, and the 

 bones jumbled about, not to speak of being trampled by their 

 successors. 



What agency, hoAVever, transported the dusty sand of alien 

 derivation, which not only occurs in massive banks, but also functions 

 as the matrix of the breccias ? There is one agent which could do 

 all these things. That agency is Wind. Wind could bring the dust 

 from far away, gather it in drifts, drive it into every chink of the 

 ■scree, pile it along the steep scree-slopes and thence down the gentler 

 slopes below, leaving it for the most part unstratified, though here 

 and there with such impersistent bedding as is often to be seen in 

 dunes. If mixed with snow, melting would bring settlement, and 

 give us an explanation of the little local faults. Blocks of rock still 

 falling from the crags would mingle with the sand, whose action 

 would accentuate the tetrahedral or " dreikanter " forms. With 

 the drifting and shifting of the sand, they would frequently be under- 

 mined, and in the course of years this jDrocess (aided by the well- 

 known gliding tendency of snow) could move them far down the 

 gentler slopes, thus enabling us to account for the scattered blocks 

 which we find in the middle of the valley, and for their derivation from 

 both the northern and the southern crags. Wind would drive the 

 light land-shells before it, breaking most of them into tiny flakes, 

 •and allowing them to stand at all angles in the drifting sand. Wind 

 would leave minute quartz-grains angular, while imparting to larger 

 and heavier ones the dull and pitted surface that is characteristic 

 of dry friction. A few yards of the crag's foot at the eastern end, 

 recently disinterred, are curiously rounded, in a way that is quite 

 unlike the result of water-action upon limestone. They are pitted 

 and dimpled, with many short grooves, narrow hollows being rubbed 

 smooth, and there is a low polish in places. The phenomena closely 

 resembles the work of natural sand-blast. In the summers of better 

 seasons, a scanty vegetation could grow iipon the banks, and its 

 rootlets would leave the capillary tubes of the Holly Lane loam. 



Further, if we suppose the prevalent storms to have been from 

 a northerly direction, we can account for the absence of these dusts 

 from the high plateaux, for their feeble development upon the sea- 

 cliffs, for their great thickness along southern slopes, and for their 

 maximum accumulation at the foot of a crag of more than 60 feet 

 in depth, under whose lee they would tend to gather in drifts. We 

 can also understand why the deposits are interrupted at the lane, 

 for that lane is carried down a gap in the ridge, the blasts 

 driving through which would prevent accumulation. 



Finally, the same hypothesis will enable as to account for the 

 concentration of the bones along the cliff's foot, and especially within 



