PHYSICAL CONDITIONS— POSTGLACIAL. 499 



CHAPTER XXL 



CLIMATIC AND GEOGRAPHICAL CONDITIONS OF POSTGLACIAL 

 AND EECENT PERIODS — SUMMARY. 



Genial conditions in Southern Scandinavia — Mediterranean molluscs in Northern 

 Seas — Southern forms in Gulf of St. Lawrence — Condition of Northern Sea 

 in latest glacial epoch — Immigration of southern species in postglacial 

 times — Migration of arctic flora in late glacial and early postglacial times — 

 Edward Forbes on origin of British fauna, and flora — Contrasts between Bri- 

 tain and Ireland — Large postglacial lake occupying bed of Irish Sea — Ireland 

 derived its fauna and flora in part from Scotland — Genial climatic condi- 

 tions — Former greater range of forests — Trees in peat of Fserbe Islands and 

 Norway — Peat with pine on shores of "Wellington Channel — Origin of floras 

 of Fseroe Islands, Iceland, and Greenland — Former connection of those 

 regions with Europe in postglacial times — Traces of former genial conditions 

 in Kurland — Gradual disappearance of genial climate and submergence of 

 land in north and north-west — Formation of 50-feet beach of Scotland — 

 Local glaciers and swollen rivers — Cold and humid conditions, and increase 

 of peat-bogs — Retreat of sea and amelioration of climate — Second great forest- 

 growth — Second peat-forming period — The Present — Southern Europe in 

 postglacial times — Date of advent of later Prehistoric races. 



Having passed in review the evidence supplied by the Post- 

 glacial and Recent deposits, I shall now endeavour to point out 

 its general bearing upon the question of climatic and geogra- 

 phical changes. In common with other geologists, I have 

 hitherto maintained that we have no evidence in these deposits 

 for any great oscillations of climate — no mutations at all com- 

 parable in magnitude with those which took place during the 

 preceding Glacial or Pleistocene Period. My belief has been, 

 that with minor fluctuations, such as might be caused by changes 

 in the distribution of land and sea, the climate of our islands 



