156 PROCEEDINGS OF THE 



and icebergs, continued the Avork of abrasion. In process of time, 

 the rock of Ailsa became solitary, and existed under the waves, 

 often, no doubt, acting as an anchorage ground for some of those 

 monster icebergs which floated along, laden with cargoes of waste 

 lands. Nothing more easy to suppose that during the deposit of 

 the boulder clay, one of these icebergs stranding upon the summit 

 of Adsa, dropped its cargo, which, deposited beliind a boss of the 

 rock, sank into comparative security. That the currents which 

 operated were from the north-west, the summjt of the Craig bears 

 certain proof, for the length is from N.W. to S.E. After a time 

 of great abrading agency, the land slowly began to emerge from 

 the sea, and no sooner did the bare scalp of the rock rise above 

 the surface, than nature crowned it with glaciers, which began their 

 work in tearing down clifts, and grooving great gullies, one of 

 which, from near the summit to the first or uppermost terrace, is a 

 very beautiful example of the glaciers' path. Contracted at the 

 mouth, it emptied itself upon the plateau in an easterly direction, 

 and then deflected right and left to the north and south, and 

 probaljly threw ofi" icebergs on each side. 



Another elevation occurred, and over this new summit the 

 glacier puslied itself till it met the sea, leaving great moraines of 

 stones of various sizes, broken splinters of the pi'otruding rock 

 which the ice tore of and laid in its path. Elevation succeeded 

 elevation, and still the glacier wore down, and sloped the eastern 

 side, leaving evidence of its continued progress as it moved over 

 the rocks. Each successive upheaval is registered on its sloping 

 form, in the terraces Avith their moraine of stones, and the gorges 

 with their narrow-tlu-oated embouchures. The last upheaval but 

 one seems to have been followed by a long period of rest, for then 

 the beach of rolled and polished stones was raised, and the largest 

 caves hollowed out. Then came a time when the rock, with 

 Kintyre, Axran, and all the surrounding land, rose about forty 

 feet; a change in the temperature occurred; the glaciers left the 

 Craig; the iceberg, " like the baseless fabric of a vision," vanished, 

 and AUsa was left a place for the sea bird to breed, while the 

 perished land, with which it was once surrounded, now forms "the 

 dust of continents to be." Durmg this time the sea still con- 

 tinued its work, and bared the north-west face, wearing away 

 both the surrounding strata, and making the cliffs steep and 

 frowning. 



