195 



plugged with sediment and taking on the characteristics of a solid rod. With a 

 piston corer, cores up to almost 70 feet have been obtained and cores 40 feet 

 long can be obtained routinely. Simplified versions of the KuUenberg corer have 

 been made by Ewing and associates, by Frautschy, by Silverman (1952), and by 

 Whaley, and by others. The Lamont Geological Observatory group have been 

 especially successful in making deep sea coring a highly perfected and routine 

 technique, having collected cores, with a total length of about 2 miles, from the 

 Atlantic sea floor. A comparable effort is required in the Pacific Basin and the 

 Scripps Institution of Oceanography has initiated such a program. 



The value of cores lies in the relatively undisturbed nature of the sample 

 and especially because they are samples normal to the surface of deposition so 

 that successively older strata are obtained as a function of depth. Sedimentary 

 strata are commonly referred to as pages in a book from which the earth's his- 

 tory can be deciphered. It is evident that deep sea basins hold a much more 

 complete and uninterrupted sedimentary sequence than the continental sedimen- 

 tary strata. However, major changes in the terrestrial environment are prob- 

 ably required before there is a change in deep sea sedimentation. Much effort 

 should be expended in getting increasingly longer cores of the sea floor. This 

 must eventually involve lowering some source of energy to the bottom along with 

 the coring device. Perhaps rotary coring is the ultimate objective. Fortunate- 

 ly one can anticipate that even the older sediments will be only slightly consoli- 

 dated. 



Grab and Underway Samplers - Grab samplers or snappers are designed to take 

 a surface sample of the bottom. A large variety of this kind of sampler has 

 been devised. They differ largely in the size of sample they will take and in the 

 method of tripping this device upon bottom contact. Actuation of the snapper is 

 generally done either by a slack wire release as in the Peterson grab, or by a 

 foot-type trip as in the NEL snapper (1947). The jaws are generally closed by 

 weights or by being spring loaded. 



Snappers are never 100% efficient. If not carefully designed and used, 

 they often fail to trip or trip prematurely -- the latter is especially true of slack- 

 wire releases. If stony bottom is encountered, the snapper is frequently held 

 partially open by a pebble caught in the jaws. In deep water, when such failures 

 are costly of time, it is often advisable to lower a bracket which will hold 2 or 3 

 snappers so that the failure of one snapper is not serious. 



Underway samplers are a special type of grab sampler designed to obtain 

 a bottom sample from a ship underway at normal speeds. Two such devices are 

 Worzel's (1940) "BT sampler" and Emery's and Champion's "Scoopfish" (1948). 



rate dead 



terfering with the ship'.^ ..^....^^ . ^-^. ^---j ■ ~- 



fathoms which is sufficient for sampling continental shelves, 



Pratje (personal communication) of the German Hydrographic Institute 

 has recently designed a new version of an underway sampler which is reported to 

 have been used very successfully in the North Sea. It can recover about a cup- 

 ful of sediment, which is a much larger amount than that obtained by previous 

 samplers. A copy of this sampler has been made at the U.S. Navy Electronics 

 Laboratory. A preliminary evaluation shows it to be an excellent one. 



Dredges - Dredging, in the sense of the word used by marine geologists, means 

 dragging a sampler along the bottom to collect especially the gravel and larger 

 material along the path of the device. The deep sea rock dredge is generally a 



