F-13 

 According to our hypothesis, the shelf edge of Georges 

 Bank experienced canyon cutting as far back as the Santonian 

 (80 m.y.B.P.). The Cretaceous materials sampled at depths 

 below that of the Santonian are interpreted as outcrops of 

 post-Santonian canyon fill: they are composed of micaceous 

 siltstones and silty marlstone with planktonic foraminif era. 

 In contrast, the older rocks are coarse arenites and cemented 

 conglomerates of inferred fluvial or littoral origin. The 

 Paleocene and Eocene samples are also likely to be deep 

 water in origin because of their high planktonic/benthonic 

 microfossil ratios. They consist of graded calcareous 

 grainstones, possibly laid down by turbidity currents. They 

 are also considered to be canyon fill. 

 Bathymetry 



One of the primary geological objectives of this project 

 was to construct detailed bathymetric maps of Baltimore, Ocean- 

 ographer, and Lydonia Canyons. In order to accomplish this^ 

 we did a detailed acoustic profile of each canyon within the 

 navigation net discussed in Appendix E. The resulting bathy- 

 metric maps are shown in Figs. F-1, F-3, and F-5. Examination 

 of these maps shows that each of the three canyons has a 

 unique configuration. 



Baltimore Canyon (Fig. F-1) is characterized by a fairly 

 broad, flat thalweg with sloping walls. The canyon is oriented 

 northwest to southeast from head to mouth. There are many 

 small tributary channels on the walls. At approximately 

 500 meters depth in the axis there is a sharp bend of the 



