122 THE LAKE-BASINS OF IAKCONNAUGHT. 



the cliffs on both sides may be on a similar or nearly 

 similar level, as if the break had opened or gaped 

 while no vertical or horizontal movement had taken 

 place. 



The rock lake- basins of larconnaught may be in 

 corrys or maums, 1 or on hill-tops, while others are in 

 valleys, or in comparatively level plains ; always a con- 

 nection between them and one or two lines of master- 

 joints or faults is apparent, which would seem to 

 suggest that these lines of break, whether faults or 

 only shrinkage fissures, must have materially assisted 

 in the formation of rock-basins. 



During, and after, the formation of a fissure at the 

 surface of the earth, unprotected either by water, 

 ice, or the like, meteoric abrasion would modify it, 

 forming debris that in part might be carried away by 

 rain, rivers, or wind. Marine action would act nearly 

 similarly, if the fissure was lowered and came under 

 the influence of the sea ; so would also ice, if that 

 agent was subsequently formed, or if it existed prior 

 to the development of the fissure; the traces of 

 the work of these different denudants are preserved 

 in the rock-basins, fissures, gorges, and ravines of 

 larconnaught. Another feature of these rock-basins 

 is, that all the long stretches coincide with lines of 



1 Corry (coire, Celtic, pot or cauldron), a valley having a bowl shape ; 

 maum (madhm, Celtic, the inside part or hollow of the hand), a connect- 

 ing mountain gap or pass, the equivalent of col. 



