GUMMING ON THE ISLE OF MAN. 343 



interesting to observe how the axis formed by the eruption of 

 trap-rocks at right angles to this direction from the Stack of Scarlet 

 to Poolvash, and, again, the elevation of the mass of limestone form- 

 ing the Balladoole Hill, has acted as a barrier against this south-west- 

 by -south denudation. The effects of the denuding action when the 

 sea was at a higher relative level, and flowed over the low barrier 

 extending from the Stack of Scarlet to Poolvash, are somewhat 

 singular. 



We observe a series of rounded hills (PL XVII. fig. 1) situated 

 on a line from the Brough towards Kirk Arbory, the most remarkable 

 being that above the Creggins, and at Skybright near Malew Church. 

 They present the appearance of bosses of an oblate-hemispheroidal 

 shape, and consist of masses of drift gravel and sand. They have per- 

 haps formed (when the land was at a lower level) a continuous line of 

 sea-beach since broken through by a rush of water from the N.E.byE., 

 or they are the relics of the former highest level of the drift, and were 

 produced by the beating about of different currents during a period 

 of elevation. And we may observe (as in some respects connected 

 with this last view) a similar conformation in the chain of low hills 

 (reaching to about the same height) running from Point Cranstal 

 to Blue Head. This chain exhibits an appearance of having been 

 a sand-bank extending in a line parallel to the ancient northern 

 coast of the island, at the .distance of four miles from it. 



The neighbourhood of the Creggins, and the valley down which 

 the Castletown river runs, are well-worthy of study, as presenting 

 some of the most striking features of a country denuded by water at 

 different levels. I have, however, no new facts to offer with regard 

 to the age of these formations, as I cannot with certainty refer to 

 them a few shells of recent species, with bones of mammalia, obtained 

 near the surface ; since in these places it is doubtful whether they 

 may not belong to a more modern raised beach, of which notice M'ill 

 be presently taken, and which, partly covering up the older alluvium, 

 is of considerable interest as indicating an oscillatory movement of 

 the land. 



4. Alluvial JBeds,' — It has just been stated that the alluvial de- 

 posits of the island rest for the most part in large hollows formed 

 by the denudation of the drift gravel and sand down to the boulder 

 clay, and in some instances, in the south of the island, down to the 

 fundamental limestone. The numerous mountain torrents flowing 

 into these hollows have afforded abundant material for sedimentary 

 deposits wherever the imperfect drainage of the country has given 

 opportunity for the spreading out of tranquil waters into inland lakes 

 or sheltered estuaries. 



The existence of such lakes to a largo extent, even within the 

 historical period, is attested by ancient records, and by the names of 

 several places on the island*, while four of them are inserted in a 

 map of the island published in 1595. Those in the north were 



'^^ Thus we have Ballaugh (Balla lough — the place of the lake) in the north, 

 and IJalla-lough, near Castletown, in the south. Also EUau-vauc (White-island), 

 near Lc2.ayrc. 



