destruction of internal structure depends directly on the proximity 

 of the structure to the sediment surface. Structures within a few 

 centimeters of the surface are probably obliterated within a few 

 months. In an area of active bioturbation , surface structures will 

 probably be obliterated within a few weeks. 



The saturation diving and underwater habitation provided by the 

 Tektite II project are of great advantage in studying bioturbation. 

 They permit a significantly greater amount of underwater observa- 

 tion than would be possible in the same period of diving from 

 surface nearly continuous monitoring of experiments that document 

 the geologically significant effects of organisms living on or 

 within the sediment. 



References cited: 



Clifton, H. E., in press, Orientation of empty pelecypod shells 

 and shell fragments in quiet water: J. Sedimentary Petrology. 



Clifton, H. E., Mahnken, Conrad V. W., Van Derwalker, J. S., and 

 Waller, R. A., 1970, Tektite, Man-in-the-sea experiment of 

 marine science program, description and preliminary results: 

 Science v. 168,: 659-663. 



Emery, K. O. , 1968, Positions of empty pelecypod valves on the 

 continental shelf: J. Sedimentary Petrology 38: 1264-1269. 



Randall, J. E. , 1967, Food habits of reef fishes of the West 

 Indies: in Proc. Internat. Conf . on Tropical Oceanography, 

 Nov. 15-24, 1965, Miami Beach, Fla., Studies in Tropical 

 Oceanography No. 5, Univ. of Miami Inst. Marine Sciences: 

 665-847. 



Shinn, E. A., 1968, Burrowing in recent lime sediments of 

 Florida and the Bahamas: J. Paleont. 42: 879-894. 



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