134 THE OCEAN FLOOR 



extracted by the bottom water and thus re-enter the 

 oceanic circulatory system. The remarkable dissolu- 

 tion of lime from the calcareous remains of dead 

 planktonic and benthonic organisms, especially the 

 Foraminijera, is due to chemical action by the bottom 

 water. But not only the biogenetic components of the 

 deposit are thus affected. Remarkable discoveries of 

 the last few years by the Swedish mineralogist O. Mellis 

 prove that fragments of abyssal rocks are also subject 

 to progressive "weathering," in which lime is dissolved 

 away and sodium replaced by potassium. Other evi- 

 dence, obtained by Arrhenius and Riedel from 

 siliceous Pacific cores, proves that siliceous remains are 

 likewise subject to partial dissolution by the bottom 

 water. Finally, the transfer of manganese, iron, and 

 other elements from the water to the sediment through a 

 mechanism not yet fully explained is, at least in part, 

 localized to the very undermost water layers, and the 

 same applies to the radioactive elements ionium and 

 radium. 



Obviously all these happenings must be influenced 

 by the state of movement of the deep water layers. If 

 they were absolutely stagnant, the reactions and trans- 

 fers mentioned would take a tremendously long time, 

 owing to the slowness of diffusion through motionless 

 water. If, on the other hand, the bottom water is moving 

 relative to the sediment, not only will chemical re- 

 actions be speeded up through turbulence, but in addi- 

 tion mechanical effects are to be expected, disturbing 



