IS^?-] GUMMING ON THE GEOLOGY OF THE CALF OF MAN. 185 



this granite might be floated off by ordinary currents, drifted out a 

 few miles to sea, and there dropped. 



With respect to the granitic blocks found near the top of South 

 Barrule and on its western side, it is evident that unless we suppose 

 that point which is now the summit of South Barrule to have been 

 below the granitic boss at the period of the boulder formation and 

 to have been since elevated 600 feet or more, no ordinary drifting of 

 icebergs could have transported those blocks to their more elevated 

 position, as the summit of South Barrule is hardly more than a mile 

 and a half distant from the top of the granitic boss. 



But we may imagine such an effect produced by the extraordinary 

 action of great waves of translation (as described by Sir R. 1. Mur- 

 chison), acting upon masses of ice charged with these granitic blocks, 

 and bearing them to a considerable elevation even above the then 

 sea-level. 



Before concluding this paper the author has a few observations to 

 make upon the drift gravel, in addition to his notice of it in his former 

 paper on the Pleistocene deposits of the island. He there stated " it 

 is generally found capping the lower hills, and sometimes spreading 

 out into extended platforms, its materials being evidently derived 

 in great part from the boulder formation." In this deposit he classed 

 a series of rounded hills in the south of the island, situated on a line 

 from Coshnahawin to Kirk Arbory, the chief being the Creggins and 

 Skybright near Malew church. He considered that they might be 

 the relics of the highest level of the drift, and formed by the beating 

 about of the waves during a period of elevation. Now that he has 

 seen this stratified mass of gravel, sand and boulders at so elevated 

 a point as the Calf Islet, he is disposed rather to class them in the 

 " boulder clay formation," restricting the term " drift " to the more 

 regularly stratified deposits of gravel, shingle and sand, forming one 

 extended platform, rising very gradually towards the centre and 

 north of the island, of which the fragments on the lower ground of 

 the Calf Islet and on the opposite side of the Kitterland Strait pre- 

 sent the lowest elevation, which is about twenty-five feet above high 

 water. 



It indicates that there was a considerable period of quiescence in 

 the elevatory process by which the glacial sea had been gradually 

 becoming shallow. The author is of opinion that it was the sudden 

 elevation of this last sea-bottom which connected the Isle of Man 

 with the surrounding countries, and introduced the Megaceros hiber- 

 nicus, whose remains we find in the ancient freshwater alluvia in 

 various parts of the island. 



