}»art L*^ cAUiioMrKyois i.i.mksto.nk ov s. walks ((» a i.tikld. 



i:3:{ 



north of IK'iisol I'ark, it i> ivpivsciiti'd l>v slialcs cxposfd in a well 

 and in an adjacent s^nlly 200 yanls nortli-east of HoIl^occI Farm. 

 These heds have yieldetl no fossils, 



2. Crinoidal limestone and oolite.- The outcrop of the 

 middle {ifroup is marked by many disused quarries, and the 

 exj)osures indicate a development elosely similar to that Observed 

 at Toni^wynlais : namely, lower beds of richly crinoidal limestone, 

 stained red as a rule, and u])per beds of oolite, occasionally vein- 

 dolomiti/.ed and iron-stained but usually fresh. The oolite, in a 

 fresh eon<lition, is at ))resent worke«l in a (juarry 100 yards north- 

 east of Ma<'smaur Farm, east of (Jroes-faen. A quarry situated 

 immciliately west of Caer-i;\vanaf-isaf (Olam. 12 XVV A 4) exposes 

 the topmost beds of the oolite, with some intercalation of crinoidal 

 limestone, overlain by shales. In the outcrop .^outh-east of 

 Llansannor, where the oolite has been (piarried at Pen-cyrn and at 

 Newton Farm, it is found to be highly crinoidal, and to pass up 

 into thinly-bedded, argillaceous limestone. 



As in the outcroj) east of the Taff, the brachiopod-fauna of these 

 limestones is ])oor. Srhclhrlriirlla ct. rmtis/r/ff is the only 

 abundant form, but C'/to//r/rs ef. hdrdroisi.s. Caniaroto'chld 

 Dtitcliclilcdnriiais, and Spirt f'er chit lira t ns have been recorded 

 at several localities, including the above-mentioned ipiarry at 

 C'aer-gwanaf-isat. 



3. Shales with thin limestones.- The beds of the upper 

 group are seldom exposed. Two ex])osures, however, have yieldeil 

 a rich fauna ]»nictically identical with that of the same division 

 ea.st of the Taff. The.se area small quarry ( (Ham. 42X\VA2y) 

 lying midway between (Jroes-faen and HroHsein C^uarry, and a 

 stream-section ((ilam. 42 NW X22) situated loO yards .south-west 

 of Fantacpie.sta Farm, north of Hensol Park. Tlu' former ex|H)ses 

 beds very near the top of the Lower Limestone Shales, while the 

 latter reveals a lower horizon in the group: in each case the heds 

 are shales with thin limestones, the shales apparently barren, the 

 limestones erinoidal and shelly. 'I'he following" bniehiopods have 

 been recorded at both loealitirs: 



I'rotlitrhix lift", biifsns. 

 Piiiil nrtiiK hitrlingtoiieiisis. 

 Piisfiild t<iihpii{<fiiliisii. 

 Cliiiiit^lfs cf. luinlrt'iinis. 

 Srhi'll iriftteUii rf. rmiint rii 



( 'ii iiiiirnfurh ill in ifrhrlih-n m 

 Sjiirifer clnthrdtn^i, 

 Siirimiittliiiris cf. cuitpiihifii . 

 .llliijrii^ I'oittxtj}. 

 luniwf rill rnrbniiiiriii. 



In addition to the spei-ies enumerated above, the (iroe>-faen e\- 

 ptisure has yielded Spiril't rliui orhijilimta, and the section near 

 l*anta<|nesta Farm, i'lrlslnjuird d. t/rn,itr/r/nt. ()stnu*o«ls, small 

 gasti-ropods (Capnlids). and lilinlnloinrsnii oecur at lM)th localities. 



Fast of Llansannor. the (Je<»Iogieal Siu'vey ma)i represents a 

 -mall outlier of the Main Limestone, unaeeompam'e(l by faulting. 

 ( >ur ma]>]»inLr show«< tiii> area of Main Limestone a» a t«»nsj:u««. 



