GUMMING ON THE ISLE OF MAN. 341 



melting of snow and ice, and spread out quietly in the surrounding 

 waters. There appears no necessity for supposing any extraordinary 

 rush of water or more powerful waves or currents than there are at 

 present*, but simply a difference of climate. 



2. Diluvium, — To this series of deposits I refer certain beds of 

 yellow sandy loam with patches of gravel and rounded masses of 

 insular rock. It is developed on the mountain sides and filling up 

 the valleys, being cut through by the mountain torrents, which thus 

 leave flat terraces from thirty to forty feet above the present level of 

 the streams. This remarkable formation was noticed by Dr. Mac- 

 culloch, who gives it as his opinion that " its origin cannot appa- 

 rently be traced either to the present or former action of rivers, 

 since it is equally deep and predominant even where water could 

 never have flowed, but that it is due to a general diluvial action 

 from the south towards the north." I think it however more proba- 

 ble that the transporting action has come in nearly the opposite di- 

 rection, namely from north to south, or perhaps from the north-eastf. 

 In the south of the island the deposit contains boulders of the Bar- 

 rule granite, and masses of quartz-rock and metamorphic schist, de- 

 rived apparently from the same locality, and does not contain, so 

 far as I have hitherto observed, any masses of the limestone of the 

 southern basin, even where overlying the limestone, being remark- 

 ably deficient in this respect. 



It is possible to account for a large portion of these accumulations 

 in the inland valleys and on the slopes of the mountains, on the 

 simple hypothesis before suggested, of an arctic climate existing at 

 the period of the formation of the boulder clay. 



The whole of the south-eastern side of the chain of South Barrule, 

 as far south as Perwick Bay, is however scattered over with blocks of 

 the insular granite J. Now it is easy to imagine a transporting action 

 from the north-east sufficiently powerful to drive these boulders 

 along the slope of the mountain range from the granitic boss on the 

 eastern side of South Barrule. But the most remarkable circum- 

 stance is, that these boulders are found not only on the south-eastern 

 side of the ridge, but on the very top of it, and driven over to the 

 ivestern side ; they are even plentiful on Irey-na-Laa, and may be 

 seen on its very summit, and occur on the western slope down to 

 Dalby Head. Further than this, there is one large boulder, weigh- 

 ing apparently more than two tons, on the western side of South 

 Barrule, within a hundred feet of the summit, and several a few 

 hundred yards to south-west, at a little lower level. To reach this 

 point from the granitic boss on the eastern side of South Barrule, the 

 boulders nmst have been driven 600 feet in perpendicular heigiit up 



* The current now runs at the rate of eight or nine miles an hour in some 

 states of the tide, hetween the Calf of Man and the main island. 



t From observations recently made on South Barrule, I am now inclined to con- 

 sider that the diluvial action was directed from a more easterly point. — June 18 IG. 



X They occur near Arrogan-beg in Santon parish, on the Brough, on the Douglas 

 road near Ballasalla, and on the peninsula of Langness, which are points varying 

 from S.E. to S. by E. from the granitic boss on South Barrule. Sec Plates XIV. 

 and XV. 



