44 THE ANTIQUITY OF MAN 
are drawn in an opposite direction. There is the most 
clear evidence that, at the commencement of that period, 
England and the Channel Islands were joined to the 
Continent. A common estuary received the Rhine and 
Thames. The English forest lands were continuous with 
those of France. And now, where those forests grew, 
are the wide Straits of Dover, the North Sea, the English 
Channel, and the silted-up estuaries. When we come to 
estimate the period of time in which those changes could 
have been effected, we are met at once with our ignorance 
of the causes which underlie earth-movements. Mr 
Clement Reid has given years of study to the matter, 
and, in his opinion, such changes might have been effected 
in a short period of time — fifteen hundred years. Those, 
however, who base their speculations regarding what has 
happened in the past on what is happening in the present, 
will allow a much longer period ; but all must admit that 
our estimates are, at present, little more than guesses. 
To account reasonably for all the facts we have at present 
at our disposal, we must, I think, allow a period of at 
least ten thousand years for the Neolithic period. 
There is a considerable body of evidence in favour of 
explaining the elevation and depression of the land in 
relation with the periods of glaciation. The elevation of 
the southern part of England is believed to have occurred 
when the ice-sheet of the last glaciation was retreating north- 
wards. When subsidence was taking place in England, 
elevation was evidently at work in Scotland, for, as we 
have just seen, the Neolithic beaches of England are sub- 
merged, while those in Scotland are situated above the 
present shore-line. In one of these raised beaches, on 
the south shore of the Firth of Forth, Dr Edward Ewart 
discovered Neolithic flints in abundance, and certain 
burials apparently of the same period. The skulls of 
these ancient Scots are also of the river-bed type — very 
similar in size and form to the Coldrum skulls. Further 
north, in the Scandinavian Peninsula, elevation is now 
taking place at a rapid rate. Beyond the northern limits of 
Scandinavia lies the edge of the great perpetual ice-sheet. 
