ECOLOGY OF THE MURRAY ISLAND CORAL REEF. II 



areas in the western Atlantic, the Gulf of Mexico, and the Caribbean Sea was 

 gradually accumulating. Heilprin in 1891' said regarding Yucatan, "the 

 evidence is all but conclusive that there has been recent subsidence." Hayes 

 in 1899'' showed conclusively that in Nicaragua there has been recent sub- 

 mergence following a higher stand of the land and a period of gorge cutting. 

 In 1902, Hayes, Vaughan, and Spencer'' showed that in Cuba there has been 

 recent submergence, corroborating an opinion of Crosby published in 1883.* 

 Branner^ in 1904 adduced evidence indicating submergence of the lower 

 reaches of drainage courses and the formation thereby of the harbors of the 

 east coast of Brazil. He places the submergence in "probably" early Plio- 

 cene time, since when there has been emergence of about 8 meters, in places. 



E. C. Andrews^ in 1902 published as his conclusion, after a study of the 

 Queensland coast and the Great Barrier Reef of Australia, that the reef is 

 growing upon the submerged part of the Australian continental shelf, and 

 that "the continuance in width of the shelf southward of the reef limits 

 (coralline), and the great shoals thereon, points to a minor part only of the 

 shelf being formed of coral growth." 



Evidence of recent submergence of former shores of Pacific islands 

 definitely dates from the days of Dana, and during recent years has been 

 increased in volume through efforts of many investigators. 



Reginald A. Daly^ in 1910 and again in more recent publications^ has 

 called attention to the similarity in general depth of off-shore reef-bearing 

 platforms, such as that of the Great Barrier and the average depth of the 

 lagoons of coral atolls. Moreover, the generally flat and uniform character 

 of the bottoms of atoll lagoons and of the submerged platforms upon which 

 barrier reefs have arisen may indicate that the ocean's surface was at a lower 

 level in the ice age, the water having been taken out of the ocean to form 

 the ice caps surrounding the poles, upon which the attraction of this vast 

 mass of ice would still further lower the surface of the tropical seas by about 

 8 feet, in the manner described by R. S. Woodward.^ Moreover, the cold of 

 glacial times might be fatal to many coral reefs and thus, according to the 

 hypothesis of Daly, the present reefs have grown since Pleistocene times on 

 drowned platforms of marine erosion. Certainly the modern reefs of the 

 Murray Islands are placed upon a submerged limestone platform, but its 

 manner of origin and its age will not here be discussed. 



Vaughan has, during the past sixteen years or more, been active in 

 the investigation of the geologic conditions favorable for coral reef develop- 



'Proc. Acad. Natural Sci., Phila., p. 148, 1891. 



'Geol. Soc. Amer., Bull., vol. 10, pp. 339-340, 1899. 



•Geological Reconnaissance of Cuba, pp. l&-i8, 32, 33, 115, 116, 1902. 



•Bost. Soc. Nat. Hist., vol. 22, p. 128, June 1883. 



•Mus. Comp. Zool., vol. 44, pp. 169, 170, 1904. 



•Proc. Linn. Soc, New South Wales, pt. 2, pp. 146-185, 1902; also Amer. Jour. Sci., vol. 41, pp. 135-141, 1916. 



'Daly, R. A., 1910, Amer. Jour. Sci., vol. 30, pp. 297-308. 



^Idftn, 1915, Proc. Amer. Acad. Arts and Sci., vol. 51, pp. 159-251; 1916, Amer. Jour. Sci., vol. 41, pp. 153-186. 



•Woodward, R. S. 1888, Bull. U. S. Geol. Surv. No. 48, pp. 40, 70. 



