Andbew. — On the Clarendon Phosphate-deposits. 479 



and in less quantity the Ca 3 (P0 4 ) 2 . The carbonate was carried 

 away ; the phosphate was redeposited, the form of the deposits 

 being modified by local conditions." 



Comparison with Other Deposits. — The phosphates of South 

 Carolina* consist of waterworn nodules, much bored by marine 

 animals ; ph.osph.atic casts of the interior of shells are abundant. 

 The North Carolina phosphatesf are in part like the South 

 Carolina deposits, but there is also a phosphatic conglomerate 

 with teeth, bones, nodules, and quartz pebbles all well rolled 

 and rounded and cemented together. The Alabama deposits^ 

 are, like those of South Carolina, composed of shells, phosphatic 

 nodules, shell-casts, and fossils, all much worn and broken, 

 usually flat in form, and more phosphatized on one side than 

 the other. The nodular depositis of Florida§ rest on the un- 

 even surface of a calcareous rock, being associated with shells 

 and sands. At one of the quarries the soft calcareous rock 

 gradually blends at a depth of 3 ft. or 4 ft. into a massive com- 

 pact phosphate rock, similar in appearance to the phosphatic 

 fragments above, except that it is a solid mass ; it is probably 

 the ledge whence the fragments were derived, the phosphatic 

 pebbles and the sand being due to deposition on the eroded 

 surface of the calcareous rock. Carnot,|| however, holds a dif- 

 ferent opinion of these Florida deposits. He Considers them 

 of concretionary origin ; he emphasizes the high percentage of 

 CaF 2 , and argues that the concretionary action is due to the 

 concentrating action of salt water. The phosphates of the West 

 Indies, at Aruba and Sombrero, \\ and also those of Ocean and 

 Pleasant Islands,** were, originally coral limestones, now con- 

 verted into phosphate by the percolation of waters containing 

 phosphoric acid derived from the overlying deposits of bird- 

 guano. The deposits of Ottawa (Canada), ff and of many other 

 localities, occur as veins of apatite in very old igneous rocks, 

 mostly of Archaean age. The phosphates of WalesJJ consist of 

 apatite veins and of amorphous nodular deposits ; the latter 

 contain numerous remains of animal life, and are due. to the 

 phosphatization of a calcareous bed. In England§§ the de- 



* Penrose, U.S. Geol. Surv. Bull. 46, p. 61. 



f Ibid., p. 70. 



| Ibid., p. 75. 



§ Ibid., p. 78. 



|| Carnot, " Annales des Mines " (1896), vol. x, p. 228. 



IT Park, Trans. N.Z. Inst. (1902), vol. xxxv, p. 401. 

 ** Danvers Power, " Mineral Industry for 1901," vol. x, p. 533. 

 tt Park, Trans. N.Z. Inst. (1902), vol. xxxv. p. 400. 

 |t Penrose. U.S. Geol. Surv. Bull. 46. p. 80. 



'§§ Sollas. Quart. Journ. Geol. Soc. (1872). vol. xxviii, pp. 397-400; 

 Fisher, Quart. Journ. Geol. Soc. (1873), vol. xxix, p. 55. 



