BOTTOM WATERS 137 



as high up as the next water bottle, ten meters above the 

 sediment. During the measurements discussed below 

 the water bottles were kept at their given height over 

 the bottom to within one meter. 



The bottles were coated inside with ceresine, a sub- 

 stance resembling paraffin, in order to avoid contamina- 

 tion of the enclosed water by the metal. This is essen- 

 tial for successful Tyndall measurements, and in 

 addition the coating prevents an absorption of oxygen 

 by the metal parts. 



The measurements of particle distribution show that 

 a fine stratification appears near the bottom. In parti- 

 cular, a suspension of particles is often present in the 

 first few dozen meters above the bottom. The highly 

 stratified distribution indicates that the turbulence there 

 is very low. But in other places the eddy diffusion due 

 to bottom currents is sufficient to prevent deposition 

 of fine material like organic detritus and lutite, 

 particularly when the bottom is rough. 



There are also localities where there is no bottom 

 suspension and the water is extremely clear in close 

 proximity to the floor — depressions, for example, 

 where the currents are vanishins, whereas over ridges 

 and sea mounts the fine material is swept away by 

 currents. 



Clouds of particles were often encountered at dif- 

 ferent heights above the bottom. This indicates that the 

 bottom material in suspension from adjacent rises on 

 the floor is distributed laterally by currents. These 



