144 Notes on the Geological Position of the Human
by Mr. Whitaker that "the general tendency of the Thames
has been to cut its channel further and further southward, as
it is on the north that we find the widest tracts of the old
river-gravels, and on the south that the river comes nearest
to the hills."7 Now this tendency is nowhere so markedly
shown as in the contrast between its shores at Gravesend and
Tilbury. On the Kentish side we have chalk to the water's
edge, and it is evident that the channel of the Thames at
Gravesend and Rosherville was never southward of its present
position. Turning, on the other hand, to the Essex shore,
we see that a line drawn due north from Tilbury Fort, Docks,
or Railway Station, would cross an alluvial flat about a mile
and a half in breadth. Now where there is more or less
alluvium on both shores it must be impossible to have any
grounds for supposing remains deposited in a former channel,
on one side, to be either earlier or later in date than other
remains similarly deposited, but on the opposite shore of the
present stream, and at an equal distance from it. But in the
present instance it seems to me that we may fairly presume
the river to have been occupied for many centuries in slowly
and steadily cutting its channel further and further south-
ward. Consequently human or other remains deposited in its
channel when it flowed a mile due north of Tilbury Docks
would be almost certainly older than the skeleton recently
found.8 Aud any estimate of age, derived from calculations
as to the rate of deposition of the inundation-mud above the
Tilbury man, is made additionally uncertain by the existence
of the two stationary intervals marked by the peaty beds.
I will now briefly review the evidence as to the Neanderthal
skeleton and its age. It was found, in 1857, in a limestone
cavern near Dusseldorf, 60 ft. above the River Dussel, a
tributary of the Rhine. This cavern opened on to the face of
the river-cliff ou one side, and was found to have a partly filled.
up fissure communicating with the upper surface of the
country, 100 ft. above, on the other. A section showing the
7 'Geology of the London Basin' (1872), p. 381.
8 We learned from Mr. Pinker, in May, that the skeleton was found in
the tidal basin or dock nearest to the Thames.