312 O. H. Kinahan — Devon, Cornwall, and Galway. 



terraces (see Figs. 1 and 3) wliicli occur miles apart on certain hori- 

 zons, and consequently formed by and due only to a universal agent 

 like marine denudation.^ 



In the Silurian rock country it is hard to estimate what work 

 was done by marine and ice action, for since they ceased,. meteoric 

 abrasion has completed so much work that nearly all the conspicuous 

 traces of the other workers are obliterated. Still, however, to an 

 unprejudiced observer it is quite evident that each force performed 

 its allotted part in the great work, for in places on the hill-sides 

 will be found sloping shelves, one of them appearing in the accom- 

 panying sketch (Fig. 2), that are apparently the remains of the old 

 sea-terraces modified by meteoric denudation, as they occur at similar 



Fig. 2. Hills of Silurian rock (Joyce County Hills), with long meteoric drift slopes. 

 In the distance to the right of the sketch are hills formed of metamorphic rocks. 



heights to the terraces in the adjoining hills. That ice action also 

 played a conspicuous part prior to the present meteoric abrasion is 

 evident, for in some valleys large masses of glacier-formed drift still 

 remain, sometimes even being covered, and therefore preserved, by 

 the meteoric drift. Some writers have stated that the tortuous 

 abrupt deep valleys in Devonshire could not possibly have been 

 formed except by meteoric abrasion. This to me, however, seems 

 an unwarranted assertion ; moreover, it appears contrary to facts. 

 In very similar valleys in Yar-connaught, as just stated, moraine 

 drift occurs ; and if an observer examines the valleys of West Cork, 

 Ireland, more especially those in the neighbourhood of Hungry 

 Hill, on the north of Bantry Bay, he will find valleys just as 

 tortuous as any in Devonshire evidently ice formed, as their sides 

 and floors are planed, polished, and etched by ice, while at the 

 entrance of some will be found mounds of rocky drift, evidently 

 the debris of terminal moraines. In this comparison between Yar- 

 connaught and Devon, a reference to West Cork appears most appli- 

 cable, as the rocks of that country are the so-called " Devonian rocks" 

 but harder, and therefore better calculated to resist meteoric abrasion 

 than the rocks of Devonshire. Moreover, if there were the same 

 facilities in West Cork as there are in Devon for meteoric abrasion 

 to work, all traces of glacial action would have disappeared from the 



1 Attention was previously directed to these teiTaces in Clare and Galway. See 

 Geological Magazine, Vol. III., 1866, p. 337, also " Memoirs, Geological Survey, 

 Ireland," Ex. sheets, 105, 115, 116, etc. 



