GEOLOGY. 341 



i 



two countries now separated from each other by so wide an expanse of 

 ocean, Professor Forbes suggested that, at a distant period, the Spanish 

 peninsula extended far into the Atlantic, past the Azores, and that its north- 

 ern boundary was contiguous to, if not continuous with, the coast of 

 Ireland; in which case the migration of the Spanish flora would be a 

 very simple matter. The alteration in climate, caused by the geological 

 changes which were contemporary with or subsequent to the destruction of 

 this land, destroyed the mass of this southern flora remaining in Ireland, 

 leaving only a comparatively small number of the hardiest plants. An 

 important confirmation of the truth of this theory is afforded by the dis- 

 covery of a northern fauna in Vigo Bay; since the species of which this 

 fauna is composed are such as belong to the littoral and laminarian zones, 

 and therefore could only have been transmitted along coasts presenting a 

 line of rock or hard ground. As to the period at which this upheaval of 

 land between Spain and Ireland occurred, Professor Forbes fixes it as imme- 

 diately after the close of the Miocene epoch, a period which we know from 

 independent evidence to have been marked by very considerable geological 

 changes. 



Nor is this the only instance in which the investigation of the existing 

 fauna of the European seas has led to important conclusions respecting the 

 distribution of land and water in remote geological ages. From the specific 

 identity of the littoral molluscs, which are now found both upon the Euro- 

 pean and American coasts of the northern Atlantic, Professor Forbes con- 

 cludes that there must anciently have been a continuous coast-line, along 

 which these species migrated, probably from west to east; in other words, 

 that, at some former period, the north of Greenland was connected with the 

 north of Lapland by a belt of land, which cut off the communication 

 between the Arctic and Atlantic oceans. This supposition is, later in the 

 volume, confirmed by Mr. Godwin Austen on palasontological grounds. 

 The existing fauna of the European seas dates back to the times which 

 immediately followed the Eocene or Nummulitic period; not a single Eocene 

 form occurring among the species at present in existence. The oldest 

 records of the occupation of the Atlantic by any existing forms are found 

 in certain beds scattered over the west of France, known as the Faluns of 

 Touraine. A considerable proportion of the fossils of these deposits belong 

 to existing Atlantic species; but they are now found, not on the French 

 coast, but in localities several hundred miles further south. A precisely 

 similar phenomenon is presented by some old sea-beds near Selsey, on the 

 Sussex coast. Existing northern forms are not found among the fossils of 

 these old deposits. These facts tend to prove that, in former times, the 

 climate of the whole Atlantic region was much warmer than it is now, and 

 that the same forms which are now confined to the southern regions then 

 extended to a considerably more northern limit. Now this is precisely the 

 effect which would be produced by such a separation between the Arctic and 

 Atlantic oceans as that suggested by Professor Forbes. The warm waters 

 of the gulf-stream, unchecked by encountering the cold arctic current, 

 would in that case sweep up to the northern limit of the Atlantic, and the 

 temperature of the whole of that region would be materially raised. When, 

 by the agency of the same geological changes which upheaved the sea-beds 

 of Touraine and Sussex, the belt of land between Greenland and Lapland 

 was removed, and the cold arctic current admitted into the Atlantic Ocean, 

 its present character would be committed to the North Atlantic fauna, both 



