BRITISH AVONIAN CONODONT FAUNAS 23 
smaller collections were also made from Gower and Pembrokeshire. Detailed 
descriptions of the local stratigraphy have been given by George (1927 and 1954), 
Dixey & Sibly (1918) and Owen & Jones (1955). Pringle & George (1961) have 
reviewed the regional stratigraphy. 
Detailed localities and measured sections are given in Figs 59-92 (p. 246), and 
it is necessary here to give only a brief introduction to the local succession. The 
youngest strata of the Avonian, the D3 Upper Dibunophyllum Zone, or Upper 
Limestone Shale, are often cut out by Namurian overstep. The succession was 
collected by us at Mellte Bridge, at the confluence of the Rivers Mellte and Sychryd, 
near Craig-y-Dinas (SN 911079 : see Owen & Jones 1955) where it consists of 23 ft. 
of dark shales and interbedded muddy, and rarely crystalline, crinoidal limestones, 
most of them less than a foot in thickness. The samples yielded over 3,900 identifi- 
able specimens, whereas beds of similar age from the Black Lias Quarry at The 
Mumbles, Glamorgan (SS 615883) proved virtually barren in conodonts. 
The underlying Dz Beds were first collected from exposures in the valley of the 
River Nedd (SN 912122) but these proved to be unfossiliferous, and further collec- 
tions were made from Craig-y-Dinas (SN 911099) where some 64 ft. of strata are 
exposed. These consist of massive crystalline limestones with thin interbedded 
shales. Near the top of the section a thin irregular band of rolled fish framents and 
conodonts occurs. The samples yielded over 130 specimens. 
° BRECON 
Pembrokeshire 
° 
ABERGAVENNY 
OUTCROP OF CARBONIFEROUS 
LIMESTONE BRISTOL ce H 
ANN 
EL 
30 miles 
— 
Ny 
Fic. 6. Map of South Wales to show the main outcrop of the Carboniferous Limestone. 
