16. 



substrate types, sediment characteristics such as sediment 

 type and sedimentary structure were systematically noted for 

 each photograph examined. Detailed classification of substrate 

 types using photographic evidence is limited because it is 

 virtually impossible to determine grain size, composition, 

 and the degree of consolidation of sediment in a photograph. 

 However, it is possible to obtain from photographs some 

 general information about the substrate types and their dis- 

 tribution. The photographic data was augmented by analysis 

 of cored and dredged material in order to determine the nature 

 of the sediments and particularly the outcrops within the 

 canyons . 



Silt and sand are the predominant sediment types in 

 Baltimore Canyon, particularly in the shallower portion of the 

 canyon and on the canyon walls. The thalweg has a sandy 

 bottom with ripples along most of its length. In the mid 

 part of the canyon at about 500 to 1000 m. there are outcrops 

 of a fossiliferous grey siltstone, glauconitic black sandstone, 

 and a fairly fine grained tan conglomerate. Some talus 

 blocks from these outcrops were found on the canyon walls and 

 in the thalweg. The fossiliferous siltstone and conglomerate 

 were also recovered in a dredge on the west wall of the lower 

 canyon. Dark grey well-consolidated clay of Pleistocene age 

 outcrops was also found along the west wall of the canyon. 

 A number of glacial erratics ranging in size from pebbles 

 to boulders were also seen and dredged in this canyon. These 



