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 



