294 JOURNAL OF THE PLYMOUTH INSTITUTION. 
The arguments of M. Fremy, and his chemical researches into 
the " formation of coal," as described by himself in a paper read 
before the Academie des Sciences, and published in L'Houille, 
were passed under review. 
The geological relation of the Coal Measures was described. The 
several members of the Carboniferous System were alluded to, 
and the teachings of the members of the Coal Measures — shale, 
sandstone, limestone, ironstone, and fire-clay — detailed, especially 
with regard to the oscillation in the level of the sea bottom. The 
merits of the rival theories — "drift" and "in situ" — were 
discussed, the lecturer's conclusion being that the truth appeared 
not to have rested wholly with one side or the other, the advocates 
of either alike taking too narrow a view of the whole of the con- 
ditions ; in fact, each side had a measure of truth attaching to it. 
The help afforded to the controversy by the discovery of erect 
trunks was noticed, and instances quoted where such had been 
found in England, and upon the Continents of Europe and 
America. The " Great Dismal Swamp " of Virginia was cited 
as illustrating the "in situ" theory, and the comjjarative purity 
of coal beds by the existing conditions of the " cypress swamps " 
and " sunk country " of the Mississippi. The conditions necessary 
to the production of a repetition of coal beds in the same vertical 
space were discussed, and the comparatively modern succession of 
forest beds adduced, ten in number, which skirt the mouth of the 
Mississippi for about two hundred miles, belonging to the " Delta " 
period of the Quaternary epoch. 
The impossibility was shown of representing geological time 
chronologically, except by very inadequate estimates, so as to arrive 
at a conclusion as to the length of time necessary for the deposi- 
tion of the Coal Measures ; but all the conditions pointed to 
immensity in point of time rather than brevity, as argued by those 
writers of whom Dr. Eadcliffe, in the Contemporary Review of 
February, 1880, may be taken as a type. 
The occurrence of the Coal Measures in basin-shaped troughs, 
and their connection with the work of denudation, was described, 
together with the original continuity of coal-fields; e.g. South 
Wales, Forest of Dean, and South Gloucestershire ; the Northum- 
berland and Durham, with Cumberland; and the latter with 
the Kirkcudbright; also the Lancashire and North Wales. It 
was also suggested, from the nature of the dip of the strata of 
