Changes in Geography and Climate. 43 
not yet been discovered. The next stage known shows a 
submergence of about 140 feet, with a sea slightly warmer 
than that now washing the coast of Sussex. The marine 
mollusca are species living in the English Channel at the 
present day, mixed with a few that do not now range north 
of the Bay of Biscay. We know nothing of the plants of 
this stage, and it is probable that the warmth of the sea 
was mainly the result of its greater depth, which allowed 
ocean currents more freely to enter. 
After this submergence the land rose gradually, the 
climate apparently remaining unaltered, till we again find 
freshwater and estuarine deposits, laid down when sea-level 
must have been the same as at the present day, or slightly 
lower. These deposits contain a prolific fauna and flora, 
which includes several southern animals and plants, but no 
northern ones. Then succeeds another transition stage, 
about which we at present know very little, followed by a 
second glaciation, less severe than the former one, or 
perhaps characterised rather by a dry cold, which did not 
permit of so great an accumulation of snow and ice, though 
the northern parts of Britain were again glaciated. 
I may be permitted at this point to say a few words on 
the subject of the recurrence of Glacial Epochs, for it is a 
matter that closely concerns the student of the geographical 
distribution of animals and of plants, It will be unneces- 
sary to enter into theoretical questions as to the cause of 
these climatic oscillations, for they are evidently due to 
something entirely unconnected with changes in the 
physical geography of Britain or of Western Europe. 
These notes are merely a chronicle of the climatic and 
geographical changes for which we have direct evidence; a 
true connected history of Britain since it became a recog- 
nisable unit cannot yet be written. It will be observed 
that neither of the doctrines commonly taught seems to be 
