Tol. 55.] GEOLOGY OF NOETHEKN ANGLESEY. 665 



At the same time the explanation of the presence of the included 

 fragments as due to ' crush ' must not be pressed too far, for there 

 are some inclusions, especially near Llanbadrig Point, which appear 

 to be real pebbles ; and it seems that some pebbly slates have also 

 been involved in the crush-movement and contributed their contents 

 to the disrupted rocks. In some places irregular beds occur which 

 simulate the crush-conglomerates, but appear to be mainly the 

 result of crushing on pebbly slates. The true pebbles may be 

 almost as much deformed and broken by movement as interbedded 

 grit-bands. In one of these tracts of doubtful origin, north-east of 

 Ogof Gynfor, all doubt as to the ordinary clastic nature of some of 

 the inclusions was removed by finding in the rock a band of 

 conglomerate which ran for quite 20 feet without a break, and by 

 tracing patches of the same or a similar band in other parts of the 

 exposure. It is, however, no easy matter in some cases, especially 

 inland, where exposures are not continuous, to distinguish breccias 

 originally clastic from those only secondarily so : that is, between 

 crushed breccias and crush-breccias; and I have had to suspend 

 judgment as to the real nature of some strata. The existence of 

 one area of crush-conglomerate inland is, however, confirmed by 

 microscopic evidence (N.A. 62). It lies south-west of Rhyd-y- 

 clafdy, a farm east of Cemaes and north of the Amlwch Road, and 

 similar rocks are seen at intervals between this locality and Perth 

 Padrig. 



Prom Ogof Gynfor to Porth Wen the rocks show abundant 

 evidence of great movement and disturbance. Around Porth Wen 

 the disturbance is more pronounced, and the harder masses tend to 

 break up and become surrounded by the softer. In the southern 

 corner of Porth Wen Bay we again have rocks which may be called 

 crush-conglomerates. As at Penrhyn and Llanbadrig, they lie 

 among masses of limestone and quartzite, and they look like 

 disrupted beds of the Cemlyn grits and slates. East of Amlwch 

 again, the folds of the highly-coiitorted Llaneilian rocks are some- 

 times so broken that the harder grit-bands are shattered and 

 discontinuous ; but the disruption is rarely complete. 



(iv) Western part of the north coast. — The ragged aspect 

 of the rocks which characterizes the crush-conglomerate coast- 

 scenery around Cemaes and Wylfa reappears between Hen Berth 

 and Carmel Head, and becomes more conspicuous as we pass west- 

 ward. It has already been seen that Carmel Head , is an area of 

 powerful thrust-faults, and we may well expect to find crush- 

 l)reccias here. The green beds depicted in fig. 1 (p. 645) have 

 this brecciated character. At the extreme west, on Carmel Head 

 itself, a strip of the Cemaes limestone is folded in with the crush- 

 conglomerate, and fragments of it may be found as authiclasts 

 farther east. 



It may be inferred from the foregoing evidence that the north 

 •coast of Anglesey from end to end has been intensely crushed. 

 Along those portions of the coast where the rocks are fairly homo- 



