BRITISH AVONIAN CONODONT FAUNAS II 
limit of that zone at the base of the Menard. Klapper (1966) described Upper 
Devonian and Lower Mississippian faunas from Montana, Wyoming and South 
Dakota, and identified the local equivalents of the German Cu I and Cu IT « faunas. 
These studies have provided a most useful basis for the correlation of our Avonian 
faunas with those of the Mississippi Valley. 
Australia 
Recent studies by Glenister & Crespin (1959), Glenister (1960), Jones & Druce 
(1966) and Glenister & Klapper (1966) have shown the similarity of European— 
North American Devonian and Lower Carboniferous conodont faunas to those of 
comparable age in Australia. 
Ill. STRATIGRAPHY 
(a) Introduction to the stratigraphy of the Carboniferous of Britain 
Rocks of Lower Carboniferous age form one of the most extensive outcrop belts in 
the geology of Britain but, in spite of their extensive outcrop, generally good expo- 
sure, and the wealth of study devoted to them, precise correlation is often difficult 
between basins, and sometimes also within them. The distribution and character 
of Lower Carboniferous rocks is so well known that it needs only the merest introduc- 
tion in a study such as this, as it has recently been reviewed by George (1958). 
Lower Carboniferous rocks were deposited on an archipelago-like basement (Fig. 
1) dominated by a landmass to the north-west, by a caledonoid-trending massif 
which extended from north-eastern Ireland into the Southern Uplands, by a stable 
block in north-eastern England, and a great, east-west landmass, stretching from 
Leinster through Central Wales into the Midlands of England. To the south of this 
landmass, the south-western Province of the Carboniferous represented a basin of 
more or less continuous deposition, which extended westwards into Ireland and was 
bounded by a landmass in south-western Cornwall. It was marked by the deposi- 
tion of two distinctive facies groups. In the south, the Culm facies of Devon and 
Cornwall and southern Ireland included dark argillaceous and sometimes calcareous 
shales and mudstones, containing a few thin, impure, dark limestones and cherts, as 
well as subordinate sandstones and grits. To the north of this facies, in Somerset, 
Gloucestershire and South Wales, there was deposited the “‘ limestone facies,”’ 
consisting mainly of grey or light-blue bioclastic limestones, with subordinate 
dolomites, oolites and argillaceous limestones. These rocks contain a rich fauna of 
brachiopods and corals, as well as crinoids, ostracods, foraminifera and algae. In 
some parts of the section there is developed a “‘ lagoon’”’ facies, characterized by 
drab grey, calcite-mudstones, with subordinate calcareous shales and oolitic rocks. 
Calcareous algae, ostracods, gastropods and pelecypods are the main fossils of this 
group, which is present in the Modiola phase of south-western England. Both the 
Culm facies and the bioclastic limestone facies extend westwards into southern 
Ireland. 
Northern England was separated from Southern England for at least part of 
Carboniferous times, by the combined St. George’s Land—Midland Barrier. In the 
