Vice-President’s Address. 215 
In the Northumberland and Durham Coal Field, the strata 
from the “ High Main Coal” downwards, are shown by their 
fossil plants to be Lower Coal-Measures, if some of the 
lowest seams are not even in the Millstone Grit, as supposed 
by some geologists. I have not seen any fossils, so far as 
I can remember, from, what is described as the “Upper 
Series” of this coal field,! so cannot express any opinion as 
to its age. 
The coals worked in the Derbyshire Coal Field, near Doe 
Hill and Chesterfield, are of Middle Coal-Measure age, but I 
have not a full knowledge of this coal field. 
There are other coal fields in England of whose flora 
little is known, and till the fossil plants from these areas 
have been examined more fully, it is unsafe to express any 
opinion as to which division of the Coal-Measures they 
occupy. ‘The age of those seams from which I have seen 
fossil plants in these cases is easily determined, but possibly 
other horizons occur than those from which I have seen 
specimens. Hence, though I am able to say that one or 
other horizon of the Coal-Measures are present in certain 
areas, I cannot say that these are the only divisions of the 
Coal-Measures occurring in the districts here referred to, so, 
on the age of those coal fields whose flora is only partially 
worked up, I make no remarks at present. 
MILLSTONE GRIT SERIES. 
This series consists of grits, sandstones, white or reddish 
shales and clays, with a few thin coal seams. 
In the Barnsley Coal Field, North Lancashire, according 
to Professor Hull, these rocks attain a thickness of 5500 
feet.” 
Owing to the pervious and coarse-grained nature of the 
sandstones occurring in the Millstone Grit Series, traces of 
fossil plants.are very rare, and the shales hitherto have 
proved generally barren. 
' Hull, Coal Fields of Great Britain, 4th edition, 1881, p. 276. 
2 Ibid., p. 218. . 
VOL, XII. P 
