Vol. 65.] GLACIAL EROSION IN NORTH WALES. 289 



has taken place even over the mountain-summits, the following 

 statement : — 



'The birder rocks now stand out as rugged mountains, not because of extra 

 rending and disturbance there, but because they have been and are more 

 difficult to wear away ' (1866, p. 237 ; 1881, p. 329). 



Had the work of planation been done chiefly by the sea, the border 

 of the unreduced masses should have been a sea-cliff. Had the 

 work been done by subaerial erosion alone, there would presumably 

 be a gradual transition from unreduced masses to the reduced 

 plain. So far as I can learn, it is the latter case that corresponds 

 with the present facts of upland form ; and it is chiefly for this 

 reason that the upland seems to me to deserve classification with 

 peneplains of subaerial erosion, rather than with plains of marine 

 denudation. It is true that Ramsay thought that in certain parts 

 of the interior 



' the old sea-cliffs are still quite precipitous, strongly reminding the beholder 

 of the high old red sandstone cliffs on the east coast of South Pembrokeshh'e' 

 (184H, p.°331) ; 



but it must be remembered that this passage was written at a time 

 when it was believed that nearly all cliffs and escarpments— even 

 those of the Weald —were the work of the sea. Whatever the 

 case may be in other parts of Wales, there does not seem to be 

 any recognizable line of elevated sea-cliffs or bluffs surrounding the 

 Snowdon district. Still, it should not be overlooked that the work 

 of the later cycle of erosion, introduced by the broad. uplift of the 

 region, may have so far modified these critical features as to make 

 their discrimination difficult, if not impossible, to-day : hence no 

 definite conclusion is announced on this point. However, if proba- 

 bility may be taken as our guide, the upland of Wales may be 

 treated as an uplifted and dissected peneplain of subaerial erosion. 

 Under this interpretation, the residual mountains would be classed 

 as mouadnocks. 1 As such they must have been reduced, in a damp 

 climate like that of Wales, to well-subdued or rounded forms by 

 the time the large neighbouring areas of somewhat less resistant 

 rocks were reduced to a surface of small relief, whether that sur- 

 face was the work of marine or of subaerial erosion : this point 

 will be again referred to farther on. 



1 In conversation with several English physiographers and physical 

 geologists, I have found that they hesitate to use the term monad nock 

 because it is ' barbarous,' or ' harsh,' or ' too long.' Such hesitation seems 

 somewhat arbitrary, in view of the established use of such a trisyllable as 

 ' meander,' of the recommended use of so harsh a word as ' bergschrund,' and 

 of the frequent employment of so barbarous a term as ' nunatak.' However, 

 I have no great attachment to monadnock, and no wish to press its claim of 

 priority as a technical term ; but, until some acceptable term is introduced and 

 generally adopted, monadnock seems to me worth using, because it shares with 

 steppe, atoll, tundra, moraine, bergschrund, wady, meander, nunatak, and 

 various other current terms that have been introduced from other languages 

 into English, the practical value of being a concise name for a definite, 

 important, and more or less complicated geographical concept, which the 

 English language does not express in any single word. 



