504 Edivanl Greenly — Glaciatlon oj Holyhead Mountain. 



the original Sole Bay. The seam of shelly crag at the foot of 

 Easton High Cliff was uncovered a year ago for the length of 

 40 yards, but is now entirely hidden by masses fallen from the cliff. 

 The measures of loss (nine years) are as follows : — 



Easton Cliff, southern end ... ... ... 350 feet. 



Roadway, Easton Bavents ... ... ... 163 ,, 



Easton High Ch"ff 77 „ 



COVEHITHE. 



Beyond Easton Broad the cliffs leading to Covehithe are con- 

 stantly presenting new faces with bright yellow and pink colouring, 

 suggestive of Alum Bay. The losses would probably have been 

 greater but for ledges of hard sand rock projecting some 10 to 

 12 feet, and acting as benches for the support of the upper 

 strata. At Covehithe roadway, starting from the hedge and cliff 

 barrier, frequent measurements have been taken since 1895, showing 

 gradual diminution iu length from 62 yards to a remnant of 19 yards. 

 Total loss in nine years = 129 feet.^ 



XL — The Glaciation of Holyhead Mountain. 



By Edwakd Greenly, F.G.S.^ 



rpHE bare and rocky hill known as Holyhead Mountain is of 

 _L considerable intei'est iu connection with recent geological events, 

 standing as it does some thirty miles out from the highlands of 

 Carnarvonshire into the Irish Sea Basin ; and in such remarkable 

 isolation, for it is much the highest of the five hills which rise above 

 the general level of the platform of Anglesey. 



Its height is only 721 feet, but so strongly featured is it, especially 

 towards the west, that one feels the term ' mountain ' to be no 

 misnomer, and can hardly believe it to be really lower than many 

 of our smooth wolds and downs of Oolite and Chalk. Being 

 composed, moreover, of white quartzite (or more properly of 

 quartzite-schist), and being so bare of vegetation, it recalls much 

 more vividly certain types of scenery in the Scottish Highlands 

 than anything in those Welsh mountains that one sees from its 

 sides. Towards the east it slopes at a moderate angle, but a little 

 west of the summit it is traversed by a very strong feature, due to 

 a fault, running nearly north and south, along which is a line of 

 great crags, facing west, and prolonged northwards into the still 

 greater sea cliffs towards the North Stack. Beyond this the land 

 still remains high, but is smoother in outline, a somewhat softer 

 series of rocks extending from the fault to the South Stack, where 

 the high moors end off in great cliffs above the sea. 



1 The author's communication was illustrated by maps and photographs, and 

 a discussion followed as to the best means of artificial protection. 



- Eead before the British Association, Cambridge, Section C (Geology), Aug., 1904. 



