The Limestone Rocks of North JVales, described. 163 



them, and a short stay,(in bad weather) with an ingenious FiisJid 

 near St. Asaph, could enable me to judge; unfortunately, as it 

 now appears, I had descended Rhualt Hill into the vale of CKvyd 

 on its NE side in my way from Holywell, at a point where no 

 Limestone was visible (owing, as it since appears, to its edge 

 lieing io\v, covered by alluvial clay) and wliere nothing truly 

 indicated f/ie direciion of the dip of the strata*: my Friends, 

 whom I very fullv questioned, were only able to tell me of three 

 or four detaciied patches of Limestone, on all the north-eastern 

 border of the vale of Clwyd, and which they believed to be 

 perfectly unconnected, and to dip north-castiuardly, into the 

 Mountain: from this, and what I had myself seen of the north- 

 eastern dip of the two Limestone Rocks of Holywell (or Halkin) 

 and Abergeley (or Cefn), 1 too hastily concluded, that there were 

 in this part of North Wales three Limestone Rocks far separated 

 by Slate, &c. agreeing nearly with those I had noticed near Lud- 

 low, under-lieing the Clee-hills Coal-field. 



During the last Summer and Autumn, opportunities have how- 

 ever been afforded me, by different Employers, of making a 

 pretty miimte Survey of all the Coal-field to the NW of Holy- 

 well, of examining other parts of it, and of satisfactorily tracing 

 the Limestone underlieing the Coals of North Wales. "Whereby 

 I find, instead of there being three Limestone Rocks, widely se- 

 parated by Slate, &c. that in general, four such Rocks occur, 

 (as in Derbyshire, although not here separated by Toadstone) of 

 variable thickness, and not so far separated by intervening mat- 

 ters, but the whole may be considered, in a very general view, 

 a> one Rock, and as such I shall mention it, in tlie following de- 

 scription of its range and dip. 



The Limestone enters North Wales at Great Ormeshead, rest- 

 ing on coarse Slate, with a NE dip, and so continues through 

 (^efn (on the SW of St. Asnph) : and its dip then changing to 

 near ENE, it ranges (speaking of its top) through Denbigh and 

 W of Ruthin, to nt;ir Llanelidan ; where its edge wheels round, 

 and it ranges NE for about 1| mile, successively, with a NE, 

 N and NW ilip; and making then another wheel, its direction 

 becomes N (with a W dip) ranging E of Garth-gynnan, then 

 near NNW through Llanbedr, Llanganhafal, Llangvvyfan, Tra- 



* I iiad more tlian once heard persons who had travelled this Road, 

 .■•peak of the extreme regularity of the dip to l/ie tiort/i-eastworcl, of the 

 coar.s<- Slatf, in the Quarry SW side of the Road on Rhualt Hill : but sub- 

 S»;qiiehtly I luive Councl, that these are only .s</y//?//«, almost at rit;ht angles to 

 the plane of the Limestone, when it covered the Slate here : and that where- 

 evcr I have had the opportunity in North Wales, of examining the i'liictiou 

 of these two Rocks, it is far more conwnon to iiee such stratnla in the Slate, 

 Ihiiii tooLscrvc any beds thereof parallel with those of the Limestone. 



L 2 inei'chiou 



