ABSTRACT
Shallower and deeper water assemblages were identified on the basis of their assignments to benthic assemblages (BA) (e.g. Potter and Boucot, 1992, tables 1-3; Patzkowsky, 1995, table 7): the Quarry Sandstone Member assemblage with elements typical of BA4 occurring in sub-assemblage Q1, and elements belonging to BA4 in sub-assemblage Q2; the Mitchell Siltstone Member assemblage with elements typical of BA4 occurring in sub-assemblage M1, and elements belonging to BA4 in sub-assemblage M2. The Well Field Mudstone Member assemblage (W) is compared with associations from the Dyfi Mudstone Member of the Nod Glas Formation, south of Llanymawddwy, north Wales (Lockley, 1980).
