OCEAN CURRENTS 177 



Bosporus is very small in volume, since the depths then- are 

 only 42 to 48 metres. With strong south-west winds tin- 

 surface currents are driven back into the Blark Sea, and a 

 certain amount of water of high salinity enters that way. 

 Similar conditions obtain in the Baltic, where investigations 

 have been more sustained and more thorough. 



In the Straits of Yenikale similar conditions obtain to those 

 described for the Bosporus. 



In the later Miocene period the whole of the Aral-Caspian 

 area was a continuous sea, shut off from communication with 

 the ocean or with the .Mediterranean. At the end of the 

 Miocene period this Sarmate Sea was divided up into the 

 Black and Caspian Seas. The latter was at that time united 

 with the Sea of Aral. Later, in the Quaternary period, the 

 isthmus separating the Black Sea and the Mediterranean was 

 ruptured and communication established between them. Water 

 flowed from the latter to the former, which was at a lower level, 

 and its greater depths are now rilled with water of high salinity, 

 destroying the previously existing fauna. 



The British Seas now deserve attention. They are greatly 

 influenced by the Irish branch of the Florida Current. The 

 main current towards our islands is in a northerly direction. 

 The coasts of the South of Ireland and West Wales are washed 

 by waters of the Florida Current, which has come in an 

 easterly direction from the Newfoundland Banks. 



The Lancashire Sea Fisheries Committee set out 1,045 

 drift-bottles up to 1896, of which 440, or 42 per cent., were 

 recovered. The results of these experiments are complicated 

 by two factors, tidal streams and prevailing winds. For 

 instance, many bottles set free off the Lancashire coast in 

 prevailing easterly winds in spring drifted across to the Irish 

 coast. Probably more water passes out of the Irish Sea 

 through the North Channel than enters that way, and more 

 water enters by St. George's Channel than passes out that 

 way, and there is consequently a slow current, irrespective of 

 tides, flowing from south to north in this area. But in an area 



