544  Geologieal Society: Anniversary Address, 1843. 
beds, all the animal remains with which geologists have become 
acquainted, occupying many distinct stages, have lived in the sea, 
whilst the plants, so far as I have been able to observe them (broken 
into fragments), consist of many species irregularly heaped together, 
the whole, together with the sands, grits, pebbles and shale, offering 
the clearest signs of the drifting action of water. 
On the subject, then, of the origin of coal, it would appear, that 
as our inductions can never be sound, if they repose upon one class 
of phenomena only, so do some coal strata offer indications of the 
truth of the hypothesis, that in large tracts of the world, the mineral 
was formed from vegetables which were washed into bays and es- 
tuaries, and often carried far into the then existing seas. In other 
instances, flat and marshy tracts rich in tropical vegetation, being 
subjected to gradual depressions, may have been converted into 
lagoons and swamps without any direct encroachment of the sea; 
and in this peculiar condition (subjected, however, in all cases, 
to entombment beneath those waters in which the overlying sand- 
stone and shales were accumulated), oscillations of the land may 
have raised the beds at intervals, again to be fitted for the growth 
of marshy vegetables. 
In geology more than any other science, it must be our constant 
endeavour to unravel phenomena which at one time seemed inexpli- 
cable, and often opposed to each other; but with new discoveries 
the difficulties vanish, and the apparently conflicting testimonies are 
found to be in perfect harmony with the order of changes, which 
the surface of the globe has undergone. I repeat, therefore, my 
belief, that, whilst coal may have been formed in many localities 
by subsidence of vegetables on the spot on which they grew, as first 
suggested by Brongniart, MacCulloch and others, its origin unques- 
tionably is also due, and over very large territories, to plants having 
been washed into estuaries and seas, and there equally spread out in 
successive layers with sand and mud. 
Gypsiferous Rocks in North America.—Having now disposed 
of all the subjects relating to the known deposits of decided Pale- 
ozoic age in North America, I will endeavour to show how the ex- 
amination of one continent throws light upon the structure of an- 
other, by inviting your attention to the great Gypsiferous deposits 
of North America, to which, in treating of Russia, I have already 
alluded. 
The gypsiferous strata of Nova Scotia, with their associated sand- 
stone, shale, and fossiliferous limestones, were at first referred by Mr. 
Logan to the triassic period ; an inference which he drew from the 
general character of the fossils, and their dissimilarity, as a whole, 
to those of the Carboniferous rocks of that country. This opinion, 
however, is one from which I know this author receded, upon finding 
that some of the shells which he had brought home were recognised 
by M. de Verneuil and Count Keyserling, to be identical with species 
from the Permian deposits of Russia. 
This comparison with the Russian strata has, indeed, received so 
much illustration by the arrival of a large assemblage of fossils 
