166 



REPORT — 1869. 



The reefs were doubtless developed on areas where depression and eleva- 

 tion of the sea-bottom was constant, and where old rocks were occasionally 

 sufficiently near the surface to afford a nidus for reef-species. The depths 

 around these rocks must have been considerable ; there could not have been 

 any large bodies of fresh water near, and the sea-water must have been 

 pure and in constant motion. The littoral corals resembled the CarjiophylUa 

 Smithi of our coasts in bathj'metrical distribution, and the deep-sea corals, 

 like the existing CarijophijUia borealis and Loplwhelia prolifera, were simple 

 solitary forms distributed at a depth of from 30 to 600 or more fathoms. 



The British reefs of the early Secondary period were not necessarily 

 situated in a tropical climate ; for there is no reason why reef-building corals 

 shoidd not have been able to exist and multiply in the same temperature 

 of sea-water that deep-sea corals now do. The deep-sea corals are abun- 

 dant between Norway and the Shetlands, and are quite out of the range of 

 the Gulf-stream. The Bermuda reefs are dependent upon the Gulf-stream 

 for the supply of sufficiently warm water to produce the development of 

 ova. It may have happened that the early Secondary species may not have 

 required a greater amount of sea-temperature than that in which the great 

 coral caUed Bendrophi/lUa ramea flourishes off Cadiz. These facts and 

 considerations must have some weight against the argument that, because 

 all existing reefs are tropical, all former reefs must have been so. 



If the area of Europe is compared with that of Great Britain during the 

 periods that have elapsed since the Palfeozoic epoch, the distribution of reefs 

 and centres of oscillation, and of deep-sea and littoral corals indicating very 

 stationary conditions, gives a very good idea of the successive physico- 

 geographies of the old seas. 



Great Britain. 

 Trias Uncoralliferous 



Ehsetie Few deep-sea and littoral 



corals. 

 /Zone of Amm. planorbis 



I 



angulatus 



Bucklandi 



Scattered reefs and deep- 

 sea and littoral corals. 



Barrier reefs, deep-sea and 

 littoral corals. 



Rest of Europe. 

 Rijefs in St. Cassian dis- 

 trict. 

 Reefs in Lombardy and Swit- 

 zerland. 

 Scattered reefs in France, 

 Lombardy, and Switzer- 

 land. 

 Reefs in Switzerland. Vast 

 areas with simple deep-sea 

 and littoral corals in 

 France. 

 Scattered reefs Rare deep-sea corals in Eu- 

 rope. 



Middle Lias Deep water and littoral Rare deep-sea corals. 



corals. 



Upper Lias Very uncoralliferous Very uncoralliferous. 



Inferior Oolite Successive reefs Reefs in Western Europe. 



Great Oolite Successive reefs Reefs in Western Europe. 



Coral Rag Few reefs Few reefs. 



Portland Oolite Reefs rare Reefs rare. 



Neocomian Littoral and deep-sea 



coi'als. 



Guult Littoral and 



corals. 

 Cenomanian Littoral corals 



deep-sea 



Reefs in France, Switzerland, 



Germany. 

 Littoral and deep-sea corals. 



Lower Chalk Deep-sea corals 



Upper Chalk Deep-sea corals 



Eocene Deep-sea corals and a fev 



littoral. 



Scattered reefs in France and 

 Western Germany. 



Reefs in France, Spain, Swit- 

 zerland, Germany, 



Few reefs and deep-sea corals. 



Reefs in the Lombardo-Swiss, 

 Pyrenean, and Austrian 

 areas. 



