133845.pdf

Fig. 4. Beyrichioeope ostracode range chart lor the pre-Ashgill of SW Wales, correlated with volcanic activity (local volcanic centres = black fill; abundant ash beds =
grey background) and generalized dominant lithology (dots, sandstone; dots + dashes, siltstone; dashes, shale; stratilication/benthic anoxia indicated by shading).
Ostracodes: solid circles, occurrence of species in this region; open squares, occurrence of species in other region of Welsh Basin; open circles, presence of species as
immigrant to this region. No species occur outside the Welsh Basin, although some genera are shared with Ballica, Europe and North America. Data from Jones
(1986-1987). Siveter (in press) and personal observation.