eT en ee a ee Peet ee 
Pr rere re aren rn eet 
Progress of Geology. 13 
as 1840, that great part of our coalfields was accumulated under 
marine conditions; the fossils associated with the coal-beds be- 
ing, not as had been too generally supposed, of fluviatile or lacus- 
trine character, but the spoils of marine life. Professor Henry 
gers came to the same conclusion with regard to the Ap- 
palachian coalfields in America, in 1842. Mr. ee 4 believes 
that the plant Sigillaria grew in salt water, and it is to be re- 
marked that even in the so-called “fresh water linemnelt of 
Ardwick and Le Botwood the Spirorbis and other marine shells 
are frequent, whilst many of the shells termed Cypris may prove 
to be species of Cytherea. Again, in the illustrations of the fos- 
sils which occur in the bands of iron-ore in the South Welsh 
coalfield, Mr. Salter, entering articularly into this question, has 
shown that in the so-called ‘* Unio-beds” there constantly oecurs 
a shell related to vag Mya of our coasts, which he terms Anthra- 
comya; whilst, as he has stated in the “Memoirs of the 
logical Survey,” fant issued, the very Unios of these beds have 
a peculiar aspect, differin much from that of true fresh-water 
forms. They have, he says, a strongly wrinkled epidermis, which 
is a mark of the Myadze, or such burrowing bivalve shells, and 
not of true Unionide ; they also differ in the interior, as shown 
by Professor W. King, Seeing that in these cases quietly de- 
posited limestones with marine shells (some of them indeed of 
estuary character) rest upon beds of coal, and that in many oth- 
er cases purely marine limestones alternate ng eA 4, ates 
of vegetable matter and coal, may we not be le odify the 
pres founded on the sound observation of Sir W. . a ra 
ich the formation of coal has rather too exclusively re- 
ion to terrestrial and fresh- one conditions? May we not 
rather revert to that more expansive doctrine, which I have long 
supported, that different operations of nature have brought about 
the consolidation and alteration of vegetable matter into coal? 
In other words, that in one tract the coal has been formed by 
the subsidence in situ of vast al es of former jungles and 
forests; in another, by the transport of vegetable materials into 
marine ‘estuaries ; in a third case, as in Russia and one (where 
purely marine limestones alternate with coal), ) by a succession 
of oscillations between jungles and the sea; and lastly, by the 
extensive growth of : plants in shallow seas. 
The geological map of eae OES prepared by Messrs. 
Howell and Geikie, and recently published, with its toed expla- 
nations, affords indeed the clearest proofs of the frequent alter- 
nations of beds of purely marine limestone charged with Pro- 
ducti and bands of coal, and is in direct analogy with the coal- 
fields of the Donetz, in Southern Russia.* 
* See Russia in Europe and the Ural Mountains, Vol. 1, 
