388 Geology at the British Association. 
by reference to associated graptolite-bearing beds. Evidence 
suggests that (b) is an exotic fauna, possibly southern in 
origin, which migrated into the British area. Becoming early 
established in South Scotland, it soon spread west into Ireland, 
but did not dominate the whole British area till Ashgillian 
times. 
Dr. Newell Arber described the recent advances in know- 
ledge of the rich fossil faunas of the South Staffordshire 
Coalfield. Attention had been chiefly concentrated on the 
floras of the brick clays and of the beds on the horizon of the 
bottom coal. Considerable numbers of species have been 
obtained from both horizons, of which some are new records 
both to the coalfield and to Britain. 
Dr. Marie C. Stopes described, and illustrated with photo- 
graphs, petrifications of plants in the freshwater cherts of 
Lulworth (Purbeck) and Asia Minor (Tertiary). The cherts 
contain beautifully preserved pollen-grains, fungi, stem débris, 
etc., and the existence of these delicate soft tissues so well 
preserved suggests that Sollas’s view of flint formation can 
only be applied with caution to these freshwater cherts. 
Dr. A. H. Cox gave a note on the Igneous Rocks of Ordo- 
vician age. As the sedimentary rocks of this age consisted 
chiefly of a great thickness of shales and sandstones, implying 
that the sediments were deposited over an area which was 
undergoing slow but prolonged subsidence, it was to be 
expected that the associated volcanic rocks would approximate 
to the keratophyre-spilite series, and this appears to be the 
case. The importance of the pyroclastic rocks also is very 
marked. It is not uncommon to find tuffs building up the 
whole of a thick volcanic series. This is in marked con- 
trast to all the volcanic series of later date in the British- 
Isles, and is not merely explainable by the fact that the 
eruptions were submarine, and that therefore the clastic 
products were more likely to be preserved. The further 
explanation is in the viscosity of the magmas, and this high 
viscosity has been noted in the spilites. It is just such highly 
viscous lavas that would be expected to furnish a large amount 
of pyroclastic material. This appears to be another illustration 
of the connection between rock types and types of earth 
movement. 
Dr. Hubert Cox and Professor O. T. Jones described pillow 
lavas from Strumble Head, Pembrokeshire, Cader Idris, and 
two localities in Carnarvonshire. The same authors gave the 
results of an examination of the district between Abereiddy 
and Pencaer, Pembrokeshire, which they propose to follow 
up by mapping the area in detail. 
Mr. C. V. Illing gave a valuable paper on the Stockingford 
Shales and associated beds of the Nuneaton area, in which 
Naturalist, 
