208 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1936 



forms comparatively recently. Besides these records of past life and 

 its many changes there exist a chemical and a physical record. Oxi- 

 dation and reduction and the nature of the dissolved matter in the 

 water have all left the record of their changes in the bottom, and the 

 nature and size of the minerals and rock fragments bear evidence of 

 the direction and strength of former ocean currents, the movements 

 of ice, and the depths of the ocean in the past. 



Although this great historical record has long been known to ex- 

 ist, we have been unable to profit by it, for we could read only the 

 topmost page. Heretofore, the samples obtained from the deep 

 ocean bottom have been "grab samples", a mere handful of material 

 taken from the very surface of the bottom. These samples give 

 information of present conditions only and reveal nothing of past 

 events. 



On land the geologist can study the exposed rock strata, he can 

 climb mountains and descend into mines, and he can study samples 

 from test borings and deep wells. Millions of such studies have 

 been made of the land, and a very reliable knowledge of its geologic 

 history has been assembled, but a similar study of material lying 

 beneath miles of water is enormously more difficult. Far out from 

 land, in the undisturbed depths of the open ocean, the record has 

 accumulated very slowly, so that a few feet of depth may represent 

 a very long interval of time. Therefore if we could bring up a 

 vertical section of several feet of this bottom, in its original, un- 

 disturbed condition, we might read the history of oceanic events as 

 the geologist deciphers the record in the rocks. 



The need of such samples has been felt for many years and many 

 devices to secure them have been tried. Recently an apparatus has 

 been developed which has obtained such "cores" up to 10 feet in 

 length and containing sufficient material for very comprehensive 

 studies.^ These cores have been brought up from ocean depths of 

 2,650 fathoms, which is more than 3 land-miles down. 



The apparatus is self-contained and may be attached to any exist- 

 ing sounding line strong enough to lift it. It functions automatically 

 on reaching the bottom and consists essentially of a steel tube (inside 

 which is a brass tube) which, on arriving at the bottom, is forced 

 into the sediment by an explosion of cannon powder contained in a 

 weight or "gun" attached to its upper end. When brought to the 

 surface the sample is held inside the brass tube, which is slipped out 

 and labeled, and another tube put in its place ready for another 

 sounding. The sample remains undisturbed in its brass tube until 

 opened for examination in the laboratory, 



^ Piggott, C. S., Apparatus to secure core samples from the oeean-bottom. Bull. Geol. 

 See. Amer., vol. 47, pp. 675-84. May 1936. 



