. The Quarterly journal of the Geological Society of London. coast is occupied by great crush-con-glomerates of quartzite and limestone in a slaty matrix, which canbe conveniently studied on the headland of Pen Cristin. (e) The Crush-Conglomerates of Pen Cristin. Between Henllwyn and Pen Cristin some stages in the processof disruption which has given rise to the formation of these crush-conglomerates can bePig. 5. — Overfolding in quartzite-bands traced. The shore-sec-interbedded with slates ; cliff west of tion here is remarkablyPen Cristin. like, and is as instruc- tive as, that exposed onth
. The Quarterly journal of the Geological Society of London. coast is occupied by great crush-con-glomerates of quartzite and limestone in a slaty matrix, which canbe conveniently studied on the headland of Pen Cristin. (e) The Crush-Conglomerates of Pen Cristin. Between Henllwyn and Pen Cristin some stages in the processof disruption which has given rise to the formation of these crush-conglomerates can bePig. 5. — Overfolding in quartzite-bands traced. The shore-sec-interbedded with slates ; cliff west of tion here is remarkablyPen Cristin. like, and is as instruc- tive as, that exposed onthe shores of CemaesBay (Anglesey).1 North-east of the harbour ofHenllwyn the quartziteand limestone group iswell exposed, as thickbeds contorted, folded,sheared, and broken intolenticles, lying amongslates with irregularand contorted east come slateswith numerous brokenbands and long lenti-cles of quartzite andoccasional lenticles oflimestone, which ex-hibit overfolding (fig. 5).At Pen Cristin theygive place to moreof a slaty matrix full. [The longest band shown is some 20 feet in length.]thoroughly cataclastic strata, consisting 1 Described by me in vol. lv (1899) pp. 661-65. As the lime-stones and quartzites of Bardsey are precisely like those of Northern Anglesey,no lithological description is given of them in the present paper. 524 DE. C. A. MATXEY OX THE [Oct. I913, of inclusions of grit, quartzite, and limestone, sometimes rudelyphaeoidal, sometimes irregular, and often more or less rounded,and of all sizes from large boulders to tiny pebbles (fig. 6,below). Yet, even in tbese shattered strata, traces of overfoldingcan be seen, as fragments of the same limestone-band recur againand again at various heights and at various places in the of thestrata is admittedly due to the crumpling effectof compression acting differentially on hard, brittle, and lessyielding beds (the grits and limestones) when interbedded withsofter and more e
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