NOTES ON THE CANNOCK OHASE OCOALFIELD. 33 
attention has been given to this subject by mining men in this 
District. The correlation of the various coalfields, and the identification 
of the different seams in each particular coalfield is a matter of the 
greatest scientific and commercial importance. The way in which the 
coal seams were originally formed, whether the vegetable crigin 
formed in situ or by drifting accumulations, is still in dispute, but it 
is noticeable in Staffordshire that several of the best seams of the 
South are divided in the North by layers of shale and other substances 
intervening. ‘hus the great 30 feet coal of the Black Country splits 
up further north and becomes no less than ten seams under Cannock 
Chase occupying 300 feet of strata. The bottom coal of South 
Staffordshire 12 feet thick becomes the deep and shallow seams 
under Cannoek Chase occupying 40 to 60 feet of strata. Another 
interesting division takes place at the North of Cannock Chase, 
where the deep seam itself becomes divided by a wedge of shale 
and rock which rapidly widens into 50 feet of strata. 
These instances show the difficulties in attempting to correlate 
different coalfields, or even the seams in one coalfield, merely by com- 
parisons of the respected seams, or by comparing the various thick- 
nesses of strata. 
It is certain that in whatever way the coal seams were formed 
—whether the vegetable masses grew and decayed in situ, or 
whether they were conveyed by drift—immense periods of time 
must have elapsed during the process, and the organic remains alone 
record this. ‘The dying out and extinction of old species, and the 
appearance of new species, can be traced by means of the fossils found. 
Hence it is to the Palzontological evidence that we must look 
for the accurate zoning of the Coal Measures, and such proof may 
be looked for in 
1 Fossil Plants 
2 » Shells (freshwater) 
3 » Fish 
4 Marine Beds 
It is unfortunate that but little interest has been taken in this 
subject in the Cannock Chase district, indeed we are almost entirely 
