S90 Blackwelder — The Geologic Role of Phosphorus. 



As the writer has already remarked, the animals of the sea 

 are almost never permitted to die of old age, bnt are devoured 

 sooner or later by other animals. Any that happen to die in 

 other ways are almost invariably eaten at once by scavengers. 

 Even the bones of fishes are rapidly devoured by echini and 

 certain other animals. It is conceivable, however, that in 

 rare instances the quantities might be too great for the capaci- 

 ties of the scavenger population ; and in that event a local 

 accumulation of animal matter might result. The late Sir 

 John Murray* based upon this idea a hypothesis to explain the 

 origin of the phosphatic nodules now dredged up from the sea 

 bottom in several parts of the world. In another workf, 'he 

 cited the remarkable case of the tile-fish, which in 1883 were 

 killed by hundreds of millions along the Atlantic coast of the 

 United States, presumably by a sudden fall of water- tempera- 

 ture brought about by the shifting of the position of the cold 

 northern current between the Gulf Stream and the coast. 

 Using Murray's figures for the area and number of the fish, the 

 writer estimates that enough were killed at this time to make a 

 layer of fish substance about four millimeters deep over the 

 affected area, if all had fallen to the bottom and had been uui- 

 formly distributed. Other instances of this kind have been 

 reported and fish are known to have been killed in great num- 

 bers by submarine earthquake shocks, submarine volcanic erup- 

 tions, and other catastrophes. It might be supposed that in 

 such cases a layer of bones and teeth would be left upon the 

 bottom of the sea, and if the process were repeated at inter- 

 vals, the layer might gradually attain noteworthy thickness. 

 It should be remembered, however, that the carcasses of dead 

 vertebrates generally float, because distended by the gases of 

 putrefaction ; and both while floating and after lodgment upon 

 the shore they are subject to the attack of scavengers as well 

 as to the final decomposing action of micro-organisms. As a 

 final result, but little of the original fish remains except the 

 points of the teeth, which being almost wholly mineral matter 

 apparently contain too little nutritive substance either to attract 

 the spoilers or to serve the purposes of bacteria. Under these 

 circumstances, it is difficult to imagine how a layer of carcasses 

 could be deposited in the open sea. On the assumption, how- 

 ever, that it is possible, Murray outlined a process of fermen- 

 tive decay and chemical interchange which is essentially that to 

 be detailed below. It is chiefly this source of supply that is 

 here laid open to question. 



As an incident in the normal life of vast numbers of organ- 

 isms, both on the sea floor and in the upper waters, shells and 



* Murray, Sir John, Challenger Expedition Eeport, Deep Sea Deposits, pp. 

 396-399. 



f Murray, Sir John, Geogr. Jonrn., vol. xii, p. 113, 1898. 



