THE FUNGT OF WARWICKSHIRE 
287 
these coals are separated by as much as 60 feet of sedimentary 
strata, but when traced southwards they are found to come 
rapidly together, and, at the Moira Colliery, form a single 
undivided bed of about 14 feet thick. Now we know from 
the conditions under which coal has been formed that the 
beds must have been laid down on a perfectly horizontal 
surface. After a sufficient thickness of peat to form the 
Nether Coal had accumulated, subsidence must have been 
commenced, which gradually increased in amount towards 
the north, and thus effectually prevented the continued 
growth of the peat bed in that direction, whilst in the south 
the growth was uninterrupted. By and by subsidence ceased, 
and allowed the forest growth which was to produce the Over 
Coal to spread once more over the whole area. In this way 
only can we account for the splitting up of a coal bed. 
Both in the Warwickshire and in the South Staffordshire 
Coalfield we find this splitting up of the Coal Seams even 
more marked than it is in our district, and the splitting up 
in both cases takes place, as in our Ashby Coalfield, towards 
the north. In the South Staffordshire district, in the neigh¬ 
bourhood of Dudley, the ten yard Coal, as it is called, is an 
undivided seam thirty feet thick ; but when traced northwards 
within a distance of a few miles it divides into nine distinct 
seams, separated by an aggregate thickness of 420 feet of 
Sandstone. The combined thickness of these nine seams of 
Coal is only a little short of the original thickness of the 
undivided seam, so that besides having here a good example of 
horizontally progressive and intermittent subsidence, we have 
an indication of the extreme slowness with which the peat 
beds must have increased in thickness. The time taken to 
accumulate 420 feet of sedimentary strata was only sufficient 
to add at the outside a foot or two to the thickness of the 
coal seam. 
(To be continued.) 
THE FUNGI OF WARWICKSHIRE. 
BY W. B. GROVE, B.A., AND J. E. BAGNALL, A.L.S. 
(Continued from page 260.) 
Sub-genus X.— Volvaria. 
153. Ag. volvaceus, Bull. Stoves. Rare. July. Cucumber 
frame, Rev. E. H. Knowles, Kenilworth, July, 1871, 
Russell, Illustr. 
