SECT. 3] 



PELAGIC SEDIMENTS 



719 



125°30'W 



25' 



25 



20' 



N - 



- 25' 



- 2a 



10° 15' 



10°15' 



CHUBASCO SPECIAL AREA 



CONTOUR INTERVAL ID FATHOMS 



3 

 NAUTICAL MILES 



Fig. 41. Topography of area around stations Chub 8, 9, 10 and 11 in North Equatorial 

 clay facies. (Dashed Hnes indicate the sounding track.) At stations 9 and 10 on the 

 topographic high the Tertiary clay formation is covered only by about 40 cm of 

 Quaternary. The cores 8 and 11, however, which are 160 and 175 cm long respectively, 

 do not penetrate through the Quaternary formation in the valley bottom. The simi- 

 larity in stratification between cores 8 and 11 suggests that the greater thickness of 

 the Quaternary formation in the valley is not caused by slumping. The abnormal 

 thinness of the Quaternary strata on the slope and crest of the hill consequently 

 appears to be due either to a persistently lower rate of accumulation or to a period 

 of non-deposition represented by the Tertiary-Quaternary unconformity. (From 

 Bramlette and Arrhenius, unpublished; topographic survey by R. L. Fisher.) 



