Changes in Geography and Climate. 37 
degree affected the climate of Britain. Man first appeared 
in Britain during the latter half of the Pleistocene Period; 
or rather we should perhaps say, that we have as yet no 
satisfactory evidence of his earlier incoming. 
The physical geography of Britain during the period 
which saw the formation of the Glacial and Paleolithic 
deposits is still uncertain in many points. I think, how- 
ever, that the evidence warrants us in saying that no very 
great changes affected the boundaries of land and sea. 
Submergence of part of the land took place; but in the 
South and East of England at any rate, only to a limited 
extent, perhaps 150 feet. There was also a time when the 
land stood at a greater elevation; though in England this 
elevation above the present level does not appear to have 
exceeded 70 feet. Coast-lines have also been cut back in 
the course of time by the incessant action of the waves, 
and in other places shingle-beaches or sand-dunes have 
slightly encroached on the sea. But all these changes can 
scarcely have been sufficient greatly to modify the outline 
of Britain; though in indirect ways their influence on the 
flora must have been considerable. The changes which 
modified the Pleistocene fauna and flora were of an 
exceptional character; for, besides the enormous fall and 
the great oscillations in the temperature, the accumulation 
of vast uninhabitable deserts of ice and snow must have 
blotted out all plant life over great part of Britain. These 
deserts must also have affected the migration of the 
Arctic plants in ways that even yet have been scarcely 
recognised. 
An attempt will be made to give an outline of the 
succession of events as far as the history can be traced ; 
but it may be necessary to warn readers that I have been 
led to interpret the records somewhat differently from other 
geologists. Approaching the subject from the point of 
