86 
[February, 
The Formation of Coal . 
such as Sigillarice, Lepidodendra, and Conifetce * All we 
know of these plants teaches us that they could not grow 
in a merely vegetable soil containing but 2 or 3 per cent of 
mineral matter. Such must have been their soil for hundreds 
of generations in order to give a depth sufficient for the for- 
mation of the South Staffordshire 10 yard seam. 
All these and other difficulties that have stood so long in 
the way of a satisfactory explanation of the origin of coal 
appear to me to be removed if we suppose that during the 
Carboniferous Period Britain and other coal-beaiing 
countries had a configuration similar to that which now 
exists in Norway, viz., inland valleys terminating in marine 
estuaries, together with inland lake basins. If to. this we 
superadd the warm and humid climate usually attributed to 
the Carboniferous Period, on the testimony of its vegetable 
fossils, all the conditions requisite for producing the charac- 
teristic deposits of the Coal Measures are fulfilled. 
We have first the under-clay due to the beginning of this 
state of things, during which the hill slopes were slowly 
acquiring the first germs of subsequent forest life, and were 
nursing them in their scanty youth. The deposit, then, 
would be mineral mud with a few fossils and that frag- 
mentary or fine deposit of vegetable matter that darkens the 
carboniferous shales and stripes the sandstones. These 
characteristic striped rocks— the “ linstey ” or “ linsey ” of 
the Welsh colliers — is just such as I found in the course of 
formation in the Aachensee near the shore, as described 
The prevalence of estuarine and lacustrine fossils in the 
Coal Measures is also in accordance with this : the constitu- 
tion of coal-ash is perfectly so. Its extreme softness and 
fineness of structure; its chemical resemblance to the rocks 
around, and above, and below; the oblong basin form com- 
mon to our coal seams ; the apparent contradiction of such 
total destruction of vegetable structure common to the true 
coal seams, while immediately above and below them are 
delicate structures well preserved, is explained by the more 
rapid deposition of the latter, and the slow soddening of the 
former as above described. 
I do not, however, offer this as an explanation of the for- 
mation of every hind of coal. On the contraiy, I am satisfied 
that cannel coal, and the black shales usually associated with 
it, have a different origin from that of the ordinary varieties 
of bituminous coal. The faCt that the products of distilla- 
* Hull, On the Coal-fields of Great Britain. 
