SECT. 3] CROSS-CORRELATION OF DEEP-SEA SEDIMENT CORES 839 



Good correlation between cores V3-127 and V3-128 is evident from the 

 graphs of Fig. 3. This amounts to conclusive evidence that these two cores 

 contain continuous records of late Pleistocene events. Core V3-126 is in striking 

 contrast in spite of the fact that it came from a point only 1.6 km distant from 

 station V3-128. Comparison of the graphic logs shows that the section which 

 lies between 1.70 and 3.50 m in core V3-128 is missing from V3-126. No layer 

 of coarse winnoM^ed sediment occurs at the level of the stratigraphical hiatus 

 in V3-126, as would be expected if the hiatus were due to deep-current scour. 

 Furthermore, current scour of sufficient energy to prevent deposition of about 

 1.8 m of sediment ought to have made some impression on the corresponding 

 section in the adjacent core, V3-128. Erosion by a turbidity current cannot be 

 seriously considered; not only are the topographical positions of the core 

 stations such as to put them above the influence of the turbidity currents 

 which flowed over the surrounding abyssal plain, but station V3-126 as the 

 highest of the three ought to have been the least accessible to turbidity currents. 

 The most plausible explanation is that slumjDing was responsible for removal of 

 the missing section. 



As is often the case the gross lithology of V3-126 gives no evidence of a 

 depositional hiatus at 1.8 m. The lesson to be learned from this example is clear. 

 A single core, however free of disturbance it may appear to be, should not be 

 relied upon to yield a continuous record of Pleistocene events, and no regional 

 stratigraphical sequence should be regarded as established until a layer by layer 

 cross-correlation has been found between at least two cores. 



C. The Canaries Cores 



Fig. 1 shows the positions of the coring stations. Curves of variation in coiling 

 percentages of Globorotalia fruncatulinoides are shown in Fig. 4. Time equi- 

 valence of the zones is reasonably certain in view of the short distance, 28 km, 

 between the coring stations. Completeness of the sections is assured by the 

 close correspondence between the two curves. It is obvious that there has been 

 much disparity in rates of sediment accumulation at the two stations, that at 

 station A 180-39 having been continuously about 80% faster. Samples from 

 core Al 80-39 are consistently deficient in coarse fraction ( > 74 pi), that is in the 

 tests of planktonic Foraminifera. Presumably the tests have been settling at 

 about the same rate at both stations, but the deeper station, A 180-39, has 

 continuously received an excess of fine material. Preferential accumulation of 

 this fine sediment at the deeper station suggests that the route of travel was 

 determined by bottom topography, but the continuity of accession of fine 

 material makes it appear improbable that transportation was due to turbidity 

 currents, which are characteristically spasmodic in effect. More probably the 

 energy responsible for horizontal transportation of the fine material was 

 supplied by deep oceanic circulation. 



Comparison of the coiling curves shows that the ratio of the rates of 

 accumulation in the two cores has remained very nearly constant. Since both 



