

) 







t 



A 





>3 



I 



> 











1 



J 



Ch. XIL] 



SINCE THE EOCENE PERIOD. 



251 



though the separated lands be in sight of each other, the 

 birds" and mammalia are qnite distinct * ■ ■ 



If we reflect on these facts, and consider what a brief space 

 of time the Post-tertiary era constitutes as compared to the 

 whole of the Pliocene period, and if we then endeavour to 

 form an idea of the duration of the antecedent Eocene and 

 Miocene epochs by reference to the greater changes in organic 

 life of which they afford evidence, we shall be prepared to find 

 that a map representing the position of the land and sea in 

 the earliest division of the Eocene period, will be wholly un- 

 like the picture which corresponding portions of the globe 



now present. 



In the accompanying map (Plate I.) the proofs of submer- 

 gence, during the period alluded to, in all the districts dis- 

 tinguished by ruled lines, are of a most unequivocal character ; 

 fertile areas thus indicated are now covered by deposits con- 

 taining the fossil remains of shells and other creatures which 

 could only have lived in salt water. The most ancient part 

 of the period referred to cannot be deemed very remote, con- 

 sidered geologically ; because the deposits of the Paris and 

 London basins, and many other districts belonging to the 

 older Tertiary epoch, are newer than the greater part of the 



common 



Secondary and 



com 



sedimentary rocks, those 



Primary (M< 



globe is coin,. 



recent epoch to which this retrospect is carried, the variations 



in the distribution of land and sea depicted on the map form 

 only a part of those which must have taken place during the 



_ a _ — * __»_ -^ ^M^ >-^l vv ■♦■ y*^ 



same period. 



mer 



amount 



of Europe best known to geologists ; but we cannot deter- 



much land has become 



and there have been repeated interchanges of land and water 

 in the same places, of which no account could be taken.f 



I 



* "Wallace, A., Physical Geography of 

 Malay Archipelago, Journ. of Roy. 



Geograph. Soc. 1864. 



t In compiling this map I have 

 availed myself of the government sur- 

 veys of England, France, and Ger- 



Russia, published by Sir Roderick 

 Murchison, M. de Verneuil and Count 

 Keyserling. M. de Verneuil' s excellent 

 map of Spain has also enabled me to 

 extend the ruled lines over part of that 

 country where before his survey no 



many, and of the important map of tertiary strata were supposed to exist 



