SCOTT—-ON A FOSSILIFEROUS SHALE, CLOCH LIGHTHOUSE. 404 
copper, which were associated with the fossil tree, were derived 
from the enclosing shale, | got a friend to analyze a piece of it. 
He found “iron and alumina in great abundance, also silica—the 
iron appeared to be mostly in the ferrous state, mixed with a little 
ferric ’’—but there was no trace of copper, so that the copper we 
find associated with the fossil tree must be derived from some 
other source than the surrounding shale. 
It would appear from the fossil contents of this shale, and from 
its thin laminated structure, that while it was being deposited the 
country round about, if not the whole of mid-Scotland, was a com- 
paratively level marshy plain, through which possibly some slow- 
moving stream wended its course; that this plain was luxuriant 
with ferns, but which, although very abundant, did not present a 
great diversity of species. One species at anyrate predominated, and 
had a distribution over central Scotland from its east to its west 
coast line. That the river, or rivers, now and again overflowed 
and covered great tracts of the adjacent land and buried the 
luxuriant vegetation under a layer of mud. Ferns would again 
cover the land and be again buried, but after these alternations had 
gone on a while, there came a time when the soil seemed not so 
suitable for the growth of ferns, and calamites took their place, 
became equally abundant, and were equally subject to be now and 
again buried under the diluvium spread over the district by 
inundation. By and by trees flourished and helped to diversify 
the landscape. But another change ensued, the conditions became 
such that they could not support vegetable life, and consequently 
we find the upper part of the shale to be quite barren of organic 
remains. I have now touched on one or two points which the 
distribution of the fossil remains in this shale seem to indicate. 
I wish now to say a few words on what appear to me to be 
some interesting features in connection with the relative position 
of the rocks, on each side of the trap-dyke [shown on the section, 
Fig. 2]. It will be observed that on the upper or north side the strata, 
consisting of alternating sandstone and shale, dip considerably, as 
I have already stated, to the N.E., while on the south side of the 
dyke the strata, consisting of conglomerates and fine grained 
dark-red sandstones, are almost horizontal, having but a slight dip 
westwards, while there can be no doubt that the rocks on the 
north side of the dyke belong to the lower carboniferous group. 
I am inclined to think that those on the south side are the lower 
