312 THE ANTIQUITY OF MAN 
miles in one direction and eight in another, and must 
have formed a great deposit for such a small stream as 
the predecessor of the Sussex Ouse to lay down. Only- 
some patches and pockets of the original deposit have 
come down to us. The plateau is now 120 feet above 
the level of the sea, but it is probable that it lay almost 
at sea-level when the great sheet was being deposited. 
The formation of so extensive a gravel bed must have 
occupied a long space of time, for the oldest or bottom 
layer is apparently Pliocene in date — the upper or dis- 
turbed layer is much later, probably middle Pleistocene 
in age. Over that "wide Pliocene plain the ancient Ouse 
had meandered, shifting its bed from time to time and 
laying down gravel, sand, and fossil remains, gathered on 
the higher lands of the Weald. The present Ouse has 
cut a valley, 80 feet deep, in the plateau. That valley 
has been excavated since the time the more recent gravel 
beds were laid down on the plateau. How often the 
valley has been re-excavated, as the land rose ; how often 
it has been filled up, as the land sank, we cannot as yet tell 
because the matter has not been investigated. But it is 
clear that there have been many variations in the level 
of the land since the gravel was first laid down on the 
Piltdown plateau. The human remains lay in the most 
ancient gravel deposit. Since the Piltdown man lived, 
then, the great expanse of gravel, measuring nearly 100 
square miles, has been laid down and a valley, at least 
80 feet deep, has been slowly eroded by a comparatively 
small stream. As the first gravel was being laid down 
the culture of man was represented by rudely chipped 
stones — eoliths. As things are to-day, man's culture is 
represented by the wireless messages and aeroplanes 
which cross the Weald, and the great steamers passing 
down the channel, and the rural homes and country 
houses which everywhere meet the eye. 
No one suspected, until Mr Dawson made the dis- 
covery, that deposits of a Pliocene or early Pleistocene 
date occurred in the Weald of Sussex. It is not likely 
that Piltdown is the only site at which such deposits 
