'4.28 



INSULAR FLOE AS AND FAUNAS WITH 



[Ch. XLI. 



other there has been no land communication since the 



Miocene 



resemblance 



Our 



map (p. 407) will satisfy the reader, that if the bed of the 

 Atlantic were everywhere uplifted 100 fathoms, all the 

 principal archipelagos and islands would remain as dis- 

 connected as they are now, whereas we know that a similar 

 upward movement would unite every one of the 200 British 

 islands with each other and with the continent. Indeed, 



r 



nearly all of them would be joined to the mainland and to 

 each other with a change of level of less than 400 feet.* That 

 there have been great movements of oscillation in the British 

 area since the Glacial period is proved by independent geo- 

 logical evidence, whereas there are no signs, as before stated, 

 of any general movements of like magnitude in the Atlantic 

 area, but only here and there some evidence of partial 



upheaval. 



I have already remarked that had Porto Santo been united 

 with Madeira proper in the Newer Pliocene period, the two 

 fossil faunas would have been fused together, instead of 

 being as different as are the living native shells of the two 

 islands. In Great Britain, also, we have a fossil fauna of 

 terrestrial shells associated with the bones of the Mammoth 

 and other extinct mammalia in ancient drift : and this enables 



us to carry back the comparison oi 

 archipelagos one step farther. We 



fossils the 



same 



range of 



species, as 



in the actual or recent fauna. No less than 48 species 

 of fossil landshells were collected by the late Mr. John 

 Brown from the Post-Pliocene drift of Copford in Essex, and 

 with the exception of two Helices, (which still survive on the 

 continent,) all are of living British species. But if England 



^ed a few hundred feet, and divided iuto 



had been submer 



mi 



pected the shells associated with extinct quadrupeds in 



some marked 



in species and varieties. There is however no such contrast. 



' ^ See Map, fig. 41, ' Antiquity of Man,' by the author, p. 279. 



