HOLGATE : CARBONIFEROUS STRATA OF LEEDS. 
13 
growth, and that were not inundated with mud at various times ; 
every parting in a coal seam represents such an inundation. The 
Beeston Bed coal has in some places as many as four such partings. 
After what has been said about the mode of formation of coals, 
it is not difficult to understand why fish remains are often found in 
the roof of coal seams, and no doubt perished in numbers when the 
mud came down in large quantities. "We find numerous though 
isolated fish remains in the overlying black shales. A reference to 
the Table will show that whatever may be the thickness of the coal 
the seat earth is about 3 ft. in thickness, and that all the coal seams 
have black shale immediately overlying them. We sometimes find 
cases in which the overlying shale, and even the coal has been 
subsequently washed away by river action ; when this has been the 
case it has generally a sandstone roof, and is not to be depended 
upon for continuity or thickness. I do not, in this paper, deal 
with the properties of coal and pass on to the shale. From what 
has been previously said we should expect in all black shale 
to find numerous remains of plants, fishes and molluscs, and this 
is what we actually do find. Lepidostrobi, flattened, may be 
found by thousands in the black shale overlying the Black Bed ; 
fish remains are also common, and it is chiefly about anthracosia that 
the iron has collected into the nodules from which the best Yorkshire 
iron is made ; nodules of this kind often form about plant remains, 
but wherever they are so found they are never so rich in iron as when 
formed about those of animals, and consequently the best ironstone 
is found in the black shale. Next to the coals they contain the 
greatest number of plant and animal remains, this is proved by their 
losing so much weight when burnt. 
Blue Bind — These deposits have evidently been made in very 
quiet places. The mud of which they are formed is very fine and must 
have been held in suspension long after any perceptible motion of the 
water had ceased. In it we find perfectly preserved fronds of ferns, but 
not in large quantities, Asterophylites, not flattened, but standing 
vertically with its frill of leaves perfectly preserved ; leaves which, as 
far as I know, have not been named, and calamites are often found, as 
well as Stigmaria3, Sigillaria}, and other plant remains, the latter have 
