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Some Lower Devonian microfloras from Southern Britain

1967; Elsevier BV; Volume: 1; Issue: 1-4 Linguagem: Inglês

10.1016/0034-6667(67)90113-3

1879-0615

Margaret Grieve Mortimer,

Geological and Geophysical Studies

A new spore assemblage of Siegenian age from Llanover, south Wales is described, and compared with an assemblage of Gedinnian age recently described by Chaloner and Streel (1966) from Newport, south Wales. These are compared with other new assemblages from the Faringdon borehole, the Brightling No. 1 borehole and the Canvey Island borehole, all in the southern half of England and known from other fossils to be probably of Lower Devonian age. All five assemblages are dominated by relatively simple spore types. The Siegenian assemblage shows only a small increase in morphographical variety over the Gedinnian assemblage, but a considerable increase in the mean maximum size of the spores studied. The borehole assemblages show approximately the same size range as the Siegenian assemblage, but differ in a progressive increase in the variety of morphography represented. All are concluded to be younger, and are placed in an order according to age. Spores with bifurcate spines appear in the Canvey Island material. The youngest assemblage, from Brightling, shows a marked increase in variety over the others, and includes saccate and zonate forms as well as those with bifurcate spines. This is regarded as consistent with an Emsian age.