F-12 

 Maestrictian stages of the Upper Cretaceous; with the 

 dredging technique it is difficult to place exact limits 

 on the depths from which the rocks have been recovered. We 

 know for sure, however, that latest Cretaceous materials 

 (65 m.y.B.P.) occur as shallow as 585 m in Oceanographer 

 Canyon from dredge 10-36 of Stetson (1949) . From seismic 

 reflection profiles run parallel to (Roberson, 1964) and ours 

 perpendicular to the shelf edge, horizons dip seawards. We 

 estimate that the top of the Cretaceous descends from a 

 depth of 500 m beneath the head of Oceanographer Canyon to 

 a depth of 900 m near the regional shelf edge. 



A particularly important observation is that younger 

 rocks can be found in verifiable outcrop position at greater 

 depths than older rocks (see Ryan et al . , 1978, Fig. 6). 

 For example. Pleistocene sandy mudstone occurs in well- 

 stratified benches at depths in excess of 1500 m along the 

 margin of the Oceanographer thalweg axis (Fig. F4) . Paleo- 

 cene rocks occur at a depth of 950 m and Cretaceous rocks 

 occur at depths shallower than 800 m. The apparent strati- 

 graphic inversion of essentially authochthonous formations 

 is, in our opinion, reasonably explained with the working 

 hypothesis that the canyons have experienced previous periods 

 of cut and fill, going back into the Mesozoic. We consider 

 it important evidence that, when younger rocks are found 

 deeper than older rocks, their facies and their benthic 

 micro-faunas almost indicate non-neritic and mid-slope to 

 bathyal depositional environments. 



