182 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 6, 



terly Journal of the same year,) certain deposits were described 

 under the term Diluvium^ consisting of " yellow sandy loam with 

 patches of gravel, and rounded masses, chiefly of insular rock, de- 

 veloped on the mountain sides, and filling up the valleys in the in- 

 terior of the island." This formation he ascribed to a transporting 

 diluvial action, principally from the north-east, during the prevalence 

 of an arctic climate. The difficulty presenting itself was, that whilst 

 blocks of the South Barrule granite are found driven over the top of 

 South Barrule 600 feet above the granitic boss, and at a height of 

 1545 feet above the present level of the sea, and are plentiful on the 

 south-western side, blocks of the same granite are scattered also over 

 the southern area of the island, and are found at points even south- 

 eastward of the granitic boss. 



The author is now inclined to place a larger portion of these de- 

 posits, than he had previously done, under the head of the Boulder 

 Clay formation, which he supposes to havebeenaggregatedin an arctic 

 climate belotv the then ordinary sea-level, and by ordinary currents 

 without any necessarily violent diluvial action, though he would not 

 by any means exclude such an action at intervals during the forma- 

 tion. He now presumes that an elevation of the sea-bottom to the ex- 

 tent of at least 400 feet has taken place in this neighbourhood since 

 the period of the boulder deposit, and he is inclined to think that the 

 curved line on the southern side of South Barrule, indicating the ex- 

 tent of the tertiary formations (coloured yellow in his general Map 

 of the Isle of Man), points out very nearly the ancient sea-shore of 

 that period. These conclusions are based on an examination of the 

 conditions which seem requisite in order to account for the occur- 

 rence of the insulated mass of the boulder formation in the before- 

 mentioned locality in the Calf of Man. 



The mass itself (which is about thirteen feet thick and fifty feet 

 across in each direction) consists, as just stated, of boulders, gravel 

 and sand. The sand is chiefly at the base of the formation, and in 

 it occur a few pebbles and laminae of fine gravel ; as we ascend, the 

 size of the fragments of rock increases; we have a bed of fine, then 

 of coarse gravel, and the uppermost portion consists generally of 

 large rounded pebbles with good-sized boulders which are scratched 

 and grooved. Most if not all the rocks are foreign. There are not 

 any which the author can certainly claim as belonging to this locality. 



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