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removed, and so from the thin end of the inclined plane, and 
consequently it would have united to form a seam of coal of 
greater thickness at some parts. Considering the present 
received doctrine of Geology, and accepting the general theory 
of the formation of coal, it would be difficult to explain this 
curious phenomena satisfactorily in any other mode. In one case, 
however, the extreme thinning-out of the Argillaceous matter 
between the beds of coal occurred towards the South, but in others 
it was towards the North. Doubtless this was occasioned by the 
continued action of floods descending into valleys or low levels 
which may have been formed, and resulting in rivers which were 
confined to one locality at one time, changing their positions and 
directions at other times. Various washing out examples of this - 
class are on record, occurrences delightful from a Geological point 
of view, but disastrous in a mining sense. One of these wash- 
outs occurred in the Black Bed coal in Derbyshire, 250 yards 
in width, and has been traced for two miles. It was found on 
another occasion that a river wash-out of this class had heaped 
up the coal on one side 6ft. thick, and there was evidence that 
afterwards it had become squeezed down. We therefore see 
that the water that formed the channel in the coal measures 
had great force and velocity. From recent explorations it is 
known that this river extends a mile and a half. In other 
places, such as at Aldwack, the denuded part is more in the 
form of a lake. It would be untenable to suppose that 
vegetable matter, forming an upper seam of coal, grew upon | 
the denuded parts of previously formed and lower seams with 
which it is now found in contact. 
In the Bowson Colliery, section No. 5, the Upper Church- 
way coal had a thickness of 2ft. 6in., and the bottom part of - 
the seam was reduced to 5in., the hard marl between the coal 
being 4ft. 6in. thick. The Geological Survey, section No. 6, 
exhibits another curious difference in the formation of the 
seams of coal, for the upper seam is divided into two parts by 
two thin beds of shale and marl. The lower seam is also 
divided into two parts by a thin bed of Carbonaceous shale, 
6in. in thickness. 
