PART I.— DISPERSAL. 

 CHAPTER I. 



PAST GEOGRAPHICAL MUTATIONS AND CLIMATIC 

 CHANGES. 



British Fossil Birds — Definition of the Present Work — The British 

 Area — -West European Submarine Plateau — The British Seas 

 — Ancient Land Areas between Greenland and Europe — Effects 

 of Submergence — The great Submergence of the British Islands 

 — Evidence against it — Physical Changes during third Glacial 

 Period — Geography of Western Europe during late Pliocene, 

 Pleistocene, and early Post-Glacial Time — Commingling of 

 Pliocene and Pleistocene Species — Glaciation correlated with 

 Elevation and Subsidence — Changes in the Earth's Centre of 

 Gravity — Coast-line of British Area at the close of the Glacial 

 Epoch — Geographical and Climatal Conditions — The 50- 

 Fathom Contour — The 40-Fathom Contour — The 20-Fathom 

 Contour — The 15-Fathom Contour — Commingling of Southern 

 and Temperate Species — Absence of large Southern Mammals 

 from European Post-Glacial Deposits — The Flora and Fauna 

 of Greenland and Iceland — Post-Glacial Changes of Climate 

 — Effects of Physical and Climatal Change on Birds. 



Owing to the excessive rarity of fossil bird-remains, we 

 possess but the scantiest palaeontological evidence of 

 that avifauna which occupied the British area even during 

 Pleistocene and late Pliocene time, but judging from the 

 fragments hitherto discovered it presented very similar 

 aspects to that existing now in our islands. With 



