124 THE LAKE-BASINS OF IARCONNAUGHT. i 



through a subterranean passage by water. An ice- 

 sheet, however, appears capable of doing the work 

 more quickly, as it would lift up the blocks and 

 other detritus and carry them off, whether the hollow 

 be situated on a hill-top, in a valley, in a maum, in 

 a corry, or on a flat plain. From this it will appear, 

 that although it is probable both marine action and 

 meteoric abrasion may have accomplished a little 

 work in removing the debris produced by the cracking 

 and faulting of the rocks, yet the chief worker would 

 seem to be ice, which would account for rock-basins 

 being typical of glaciated regions. 



After the ice had disappeared from the country 

 such hollows would become filled with water, and 

 form lakes. This, however, would require, in all 

 basins above the sea-level, that the joints and " fault- 

 rock" should be water-tight, or the subterranean 

 vent incapable of carrying off the surface supply, or 

 that drift or other matter should be deposited and 

 staunch the water-basins. It is quite apparent 

 that some of the rock-basins in larconnaught have 

 subterranean passages connected with them, while 

 others have had them ; but in the latter cases 

 they have since been closed by a peaty deposit 

 carried into the lakes by wind, rain, and streams. 

 There are, however, other rock-basins, that never 

 were, and probably never will be lakes, the 

 fault-rock being so loose and incoherent that no 



