G. E.. Kinahan — Devon, Cornwall, and Galway. 311 



In Yar-connaught, or that portion of the Co. Gralway which lies 

 west of the great lakes (Mask and Corrib), the subjacent rocks are 

 capable of a three-fold division, namely : the granitic, the metamor- 

 phic, and the Silurian rocks. The first, comparatively speaking, are 

 of a homogeneous nature ; therefore the earlier denudants, the last of 

 which was Ice, formed the country over them into hills and hollows, 

 with long flowing outlines ; abrupt valleys or ravines as a rule being 

 uncommon. The metamorphic rocks being very different in their 

 composition, texture, and hardness, have been acted on very differ- 

 ently. Some were chemically hard, others chemically soft; some 

 were very susceptible to mechanical abrasion, while others were the 

 reverse ; consequently on some, such as those chemically soft, meteo- 

 ric denudation would act more than on others, while the same rock 

 might naturally be hard and tenacious, and therefore resist such 

 mechanical denudants as either marine or ice action. On these ac- 

 counts the outlines of the hills are most irregular, in places having 

 steep, nearly precipitous, sides. Fig, 1. is a sketch of some of 



Fig. 1 . Derry-clare and Ben Cor, as seen from Lough Inagh, showing terraces on the 

 slopes and flat-bottomed combes or valleys cut into the sides. 



these metamorphic rock (quartzite) hills. Among the Silurian rocks, 

 some are hard, others tenacious, but all, except perhaps some of the 

 conglomerates, disintegrate freely ; consequently, although the earlier 

 denudants gave the hills general outlines somewhat similar to those 

 formed of the metamorphic rocks, yet subsequently meteoric abrasion 

 has affected them largely ; and though most of the hills have long 

 flowing outlines, yet they are intersected by deep tortuous valleys, 

 the sides of the latter being covered by a steep talus of meteoric drift. 

 In the whole of this part of the Co. Galway (Yar-connaught) it is 

 evident that the features of the country were carved out simultaneous- 

 ly, and the agent or agents that accomplished the work wrought at one 

 and the same time in all parts. In the granite and metamorphic rock 

 countries the traces of marine and ice denudation are seen, though 

 especially in the former, more or less modified by subsequent meteoric 

 denudation. The ice action is apparent by the dressed, planed, 

 polished, and etched rooks, and the marine abrasion by a series of 



