324 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1960 



ever, some very interesting features of deep-sea geology have been re- 

 vealed. In particular, photographs have indicated the distribution 

 and the environment of the rocks. In the Pacific Ocean, millions of 

 tons of potential manganese ore have been found scattered on the deep- 

 sea bed in the form of manganese nodules. The exposed surface of 

 nearly all rocks in deep water slowly acquires a coating of manganese 

 dioxide and this can be used to indicate which way up a piece of rock 

 lay. In plate 3, figure 1, the white patches on the broken boulders are 

 probably places where a manganese coat is lacking and one can infer 

 from this that they have been disturbed quite recently from the posi- 

 tion in which they have lain for many thousands of years. The cauli- 

 flower texture seen on the rock on the left of plate 9, figure 1, is due 

 to a similar manganese crust. 



Underwater lava flows have been found photographically in a 

 region where a dredge has been unable to pick up any loose material 

 from the bottom. In plate 3, figure 2, photographed from the Amer- 

 ican research vessel Vema, the roundness of the rocks is similar to that 

 of the pillow lavas found on continental rocks and believed to have 

 been solidified under water. Once again the nodular manganese coat- 

 ing is plainly visible. 



The ripplemarks found in the deep sea are of great interest to sedi- 

 mentary geologists. At one time it was thought that the deep sea was 

 a region of very small currents and that the existence of ripplemarks 

 in a sedimentary rock indicated deposition in shallow water. We now 

 have direct evidence of ripplemarks being formed in deep water to- 

 gether with scour and sand drifts around obstacles in the sand. Plate 

 6, figure 1, shows these features in globigerina sand at a depth of 1,700 

 fathoms. 



Almost every photograph taken in the deep ocean shows evidence 

 of some kind of life existing there. In most cases it is impossible to 

 give a specific name to the animals found, since the systematic classi- 

 fication has l)een based on detail that is often not visible in a single 

 picture. However, the pictures do show the animals in their nonnal 

 habitat and in undamaged condition, whereas many of the dredged 

 specimens have suffered damage in collecting, and distortion in the re- 

 sultant pickling and storing in formalin. Plate 6, figure 2, shows an 

 unusual holothurian that was previously known only from extensively 

 damaged specimens collected by H.M.S. Challenger in 1875. 



One of the most fascinating puzzles posed by the pictures is the 

 identification of the tracks and burrows found over the wide areas of 

 the soft bottom. One must appreciate that with the sediment accumu- 

 lating at the slow rate of only a centimeter or less in a thousand years, 

 ft track once made will be visible for a very long time. Thus the 

 density of tracks reflects the activity of several thousand years. Some 



