BRITISH AVONIAN CONODONT FAUNAS 25 
These beds overlie some 80 ft. of massive crystalline limestones, which are assigned 
to the D; Subzone. Near the top a “ honeycomb ”’ is developed. These samples 
yielded no conodonts, and the underlying 300 ft. of Seg grey crystalline limestone 
also proved barren. 
The Sz and C2S; Zones were collected at Llanelli Quarry (SO 223125), the Se 
comprising over 300 ft.of dolomitic, sandy, massive bedded limestones with occasional 
brachiopod lenses. The C2; section consists of about 50 ft. of porcellanous, compact 
calcite-mudstones with some oolites and green shales (George 1954). None of the 
samples from these exposures yielded conodonts. 
The underlying Z Zone was collected at Blackrock (SO 213125) and consists of 
190 ft. of alternating oolites and sugary dolomites, with occasional thin shale bands. 
All samples in this section yielded conodonts, although some samples yielded only 
unidentifiable fragments. Over 5,000 specimens were recovered. 
The K Zone was collected in the banks of the River Clydach (SO 224126) and along 
the Heads of the Valleys Road (SO 225130), the contacts with the underlying red 
sandstone, referred to the Devonian, and the overlying Z Zone both being exposed. 
The unit consists of alternating calcarenite and shale bands, which range in thickness 
from 40 ft. tosix inches. The limestone samples all yielded conodonts but the shales 
were unproductive. 
(ii) Shropshire 
Rocks of Lower Carboniferous age are rare in Shropshire, most of which was 
emergent during early Carboniferous times. Strata of Lower Carboniferous age, 
which outcrop on the northern and southern flanks of Titterstone Clee Hill, are also 
found at Little Wenlock and Lilleshall. Our collections were made at Farlow (SO 
642808), on the northern slopes of Titterstone Clee Hill, where conglomerates and 
overlying limestones and shales of the K Zone are well exposed. The basal con- 
glomerate, which reaches a thickness of some 40 ft. in places (Ball & Dineley 1961), 
overlies Grey Farlow Sandstones of the Upper Old Red Sandstone. The K Zone is 
overlain by Z Zone oolitic limestones, which are well exposed at Oreton (SO 648806). 
The overlying Cornbrook Sandstone, once regarded as representing the Caninia Zone, 
has been shown by Jones & Owen (1961) to be of Westphalian age. In contrast, the 
youngest Lower Carboniferous strata of the Little Wenlock area represent the 
Dibunophyllum Zone. 
The Z Zone was collected at Oreton Quarry (SO 648806) where it consists of 20 ft. 
of pale cream calcarenite, which yielded abundant conodonts. 
The underlying K Zone was collected in Farlow Lane (SO 642808), the contact 
between the zones being unexposed. The K Zone consists of alternating shales and 
limestones ; the lower shales contain quartz pebbles, and lie directly above con- 
glomerates referred to the Old Red Sandstone (Farlovian). Conodonts were 
recovered from all samples. 
(iv) Yorkshire 
The Yoredale Formation (Yoredale Series of Phillips 1836) is a succession of 
