8 BOROUGH OF LEWISHAM. 
district deposits of ‘‘derived”” London Clay overlying river gravel 
of Pleistocene age. This is where the river has left its earlier 
‘bed and wandered, perhaps, half-a-mile away. Then a ‘‘hill-wash” 
-of London Clay has been brought down by rain-water, and spread 
over the river gravel to a thickness, it may be, of several feet. 
‘“‘Derived” material, and fossils derived from old beds and 
deposited by flowing water on recent formations, are frequently 
“*booby-traps” which catch the unwary. 
CHAPTER II. 
THE SUPERFICIAL GEOLOGY. 
N unsophisticated person once remarked that it was 
a merciful Providence which ordained that a river 
should flow near every large town and city, so that 
the inhabitants were supplied with water. This 
was making the mountain go to Mahomet. Joking 
aside, the existence of the Ravensbourne and its 
tributaries must have attracted human beings to our district in 
very early times. The contours of the surface suggest that a lake, 
or chain of lakelets, once occupied the valley-plain through which 
the Ravensbourne and the Pool now flow from between Southend 
and Lower Sydenham to the rising ground which commences near 
the Obelisk at Lewisham. 
It will be convenient to deal first with the Ravensbourne. 
The old village of Lewisham stands upon Ravensbourne gravel, 
but there is evidence that the locality was frequented by men of 
the Stone Age when the gravel was being laid down. 
The first Napoleon is credited with the remark that an ‘‘army 
marched upon its belly.” Previously to the domestication of 
animals, and the rise of agriculture, the needs of the human 
stomach were supplied by the wild fruits and roots of the forest, 
the fish of the streams, the birds of the air and the beasts of the 
field. These would be most plentiful in well-watered localities. 
We know that 35 years ago a trout of 2lbs. was taken in the 
Ravensbourne at Southend Village. The Thames was a salmon 
river within the historical period. The gravels prove that the 
Ravensbourne was formerly a river of considerable volume, and 
we have no doubt that very ancient Britons once took both salmon 
and trout from its waters. Our memory of the stream fifty years 
ago is that the present volume of water is only about half as much 
as it was then. The diminution in recent times may be accounted 
for by the diversion of water from springs and surface water, which 
formerly found its way to the river, into sewers. 
A reference to the Geological Drift Map will show that just 
above Catford Bridge the river-gravel extends over a width of 
