Skeleton lately found at the Tilbury Docks , Essex. 139 
generally noticed was the offensive smell of sulphuretted 
hydrogen proceeding from the plant-remains in this bed, 
though twenty feet or more below the surface. The preserva¬ 
tion of these plants in this slightly decomposed state is of 
course due to the thick clay beds, both above and below, 
which have prevented total decay. These beds are simply 
inundation mud, but their combination with the peaty beds 
is noteworthy, as it points to periods of subsidence divided by 
stationary intervals. For the reeds and other plants, the 
remains of which make up the two peaty beds seen, could not 
have grown below high-water mark, though the base of the 
lower of the two beds is now from 20 to 25 feet beneath the 
surface. The deposit of blue clay above this bed marks a 
period of subsidence, then the upper peaty bed implies a 
stationary interval, with a growth of vegetation about or 
slightly above high-water mark. The blue clay above the 
upper peaty bed points, of course, to a renewal of the 
subsidence. 
It will have been noticed that, in treating of the evidence 
of the peaty beds as showing subsidence, I have not men¬ 
tioned the third and still lower peaty bed, ascertained to exist, 
here and there, from trial-borings and the Tilbury Fort Well, 
though not visible on the day of our excursion. But this bed 
is generally found to rest directly on the sand or gravel, and 
its composition shows that it probably had an origin different 
from those of the two others. Instead of consisting of plants 
that once grew slightly above ordinary high-water mark, it is 
composed of logs of wood and other vegetable matter that has 
drifted down the channel and been deposited where the 
current was sluggish, as it is sure to be on one side of an 
island in the stream. Capt. Hall (quoted in Lyell’s ‘ Prin¬ 
ciples ’) remarks of the islands of the Mississippi that the 
interval between them and the shore is often found to be 
“ filled up by myriads of logs cemented together by mud and 
rubbish.” And as this lowest peaty bed has probably been 
formed in this way, it can offer no evidence of subsidence. 
No reader of the paper by Prof. W. J. Sollas, “ On the 
Estuaries of the Severn and its Tributaries,” 4 can fail to 
4 Quarterly Journ. Geol. Soc., November, 1883. 
