I)artli^ L'ARIK»MFEIU)US LIMKMO-NK (>l S. WALKS LUAI.FIKLD. !:'»'> 



Till' to)) of tlu- Caniuiu Oolito. wliieli is the gfiierally-ivcDi^nizLHl 

 aiviain^' line l)etween C\ an«l C^.i thus marks the upper limit of 

 the series Z-C,. This eonstitutes the hounihiry l>etween Lower 

 Avonian and Upi>er Avonian, as estahlished bv Mr. E. K. L. Dixon 

 on sti-ati«^rai)hieal wrrounds. It marks the culmination of a shallow- 

 ing movement in the South-Western Pi-ovinee whieh produced tlu- 

 widespread development of a Minliohi phase at the l)ase of C,, and^ 

 even led to emer^'enee and conse»iuent unconformity in some areas.- 

 The signiticant J/^>«//f'/'' l)hase has heen recognized at Miskin in 

 the area here descrilx-d, where it succeeds the Caninia Oolite 

 sharply (p. 1 tO). 



4. Crinoidal linu-siunes: Z,.—TheM- beds, forming the basi- 

 of the Main Limestone, are essentially dark-grey or black crinoidal 

 limestones, thinly bedded and Haggy, with argilhueous bands and 

 iKitches. A c-ui-rent- bedded roek, consisting of riehly-erinoidal 

 Kinds sej^arated l>y lenticles and streaks of eompaet argillaceous 

 limestone, is oftt'n devel(»ped. The development of chert in 

 iMxlular or ]>anded forms and the l)eekitiziition of fossils are 

 fretiuent, and silicitication sometimes results in the formation of 

 small nodules of milk-white banded clialcedony. 



The beds aiv ex])osed at many i>oints between Penlline and the 

 ueighV)Ourhood of Pentyrch : the chief exi>osurcs are six-citicd in 

 the'^faunallist, below. Eastwards from Creigiau, dolomiti- 

 /ation develops rapi<lly: but, even in their highly-dolomitized 

 condition, the l>edsare readily identiticil by their general characters 

 and their abundant brachi'oixxls. Thin seams crowded with 

 Chunetes cf. Uffrdrcuais are especially characteristic. 



Fauna. 



(iuuera an»l species of 



corals an<l brachiopods. 



Locality, 



1. 



ZaphrentiM delaiwnei Edwards* Haimo. C'ar- 



ruthers 



Puetula 8ubptMtulosa Thomas 



PnK/»r/Hx fcurhH9N>n<"(*^«H Hall. Vaugliiiu . X 



Productug cf. conr inn IIS ii(>w(}Thy ... ) X 



Choneten ff. hnrfin'njtU Phillip.s XAjXA 



Lei)taetui findlnijti (F\u\\\\}H) |X i ... 



SchellirienelUi cf. rn-nistrin (Phillips) XA 



OrthiM mirhelini L'K\ci\U' 



Camarottechia mitrheldennensu< Vaughan X 



Bpirifer clnthniluf^ MCny XA 



Syringothyriif cf. rugpUiata i'Ma.Tiin) X 



Uhyrig glabrUtria (Phillips), Vaughan 



A A 



A / 



X XA XA 



XC 



... XA X 

 X A** X A X A 

 XCl ... xc 



X ! .. 







5. 



6.1 



,\ 



-■. A , 





xA 



XA 



XA 



XC 



X ' 



X 



XA. 



XA 



XA 



X 



XC 



A = Abundant. 



C= Common. 



' A. \ uii-luin. Q. J. G. S. vol. Ixxi (IPLS 16) folding table faoinj? p. :{2. 



- Gower piiiMT. i>. .'»i2. See also "The C\)untry arouml Carnuirthen ' Mem. 

 (,ool. Surv. l[>Ui>, pp. HI s-J an.l ll... ('..iiiitry urcmm 

 1914, pp. 127-28. 



1 Haverfordwest" ibid. 



