NOTES ON THE GEOLOGICAL SECTION AT CHELMSFORD. 15
channel to a spot about half way between the two ends of the
island, separating this channel from the alternative one. This gravel
was covered by sand at a spot where the current had not been very
strong, and increased in thickness towards the spot at waich it
abruptly ended in an almost vertical bank half way between the
ends of the island. So much gravel had apparently been piled up
in this channel during the earlier part of the flood's duration that
the result had been to make the other the main course at a later
period. In the case of other alternative channels, more or less
coarse gravel was to be seen at the mouths of those which had not
been the main channels of the flooded stream. And in all these
cases the coarse gravel will some day be covered by the sand and
Diagram Plan to illustrate the effects of the Recent Floods in the
Ravensbourne at Lewisham.
G.G.—Gravel, sand, etc., deposited by the Floods. B.—> Direction of the flow of the stream.
mud which is the normal deposit of the Ravensbourne at Lewisham,
unless the conservators of the Recreation Ground modify the natural
results. In short, the Ravensbourne is making deposits to-day in a
way precisely analogous to that of the Chelmsford streams in the
days of the Mammoth.
And this brief consideration of the effects of floods in the
Ravensbourne, enables us to understand why the Mammoth at
Chelmsford became deposited in the coarse gravel. Carried down
the flooded stream, its carcase would naturally be deposited with
the gravel at the entrance to some back-water, and be covered up
by the finer material constituting the more normal deposits of the
streams in that locality. Only in times of flood can we imagine
these streams capable of carrying down a Mammoth, and of ultimately
drowning him. But the most powerful animal might easily exhaust