to the canyon floor. The floor is covered by coarse sands which are mobilized 

 into both large and small asymmetric bedforms. Ripples, megaripples, and sand 

 waves are present in the axial area down to at least 750 m. Analysis of 

 bedform shape indicates that sand is moved both up and down the canyon axis 

 with no net transport direction for sand. Silt and clay is winnowed by the 

 strong currents. Maximum current velocities measured in the axial area of 

 Oceanographer Canyon range between 75 and 100 cm/s. The floor of 

 Oceanographer Canyon is predominantly nondepositional with regard to fine 

 sediments. 



The depositional facies of Lydonia Canyon are more complex but generally 

 contain silt and clay deposits both on the canyon walls and in the axial area. 

 Current velocities within this canyon are reduced relative to Oceanographer 

 Canyon. 



Small, shallow canyons such as Heeltapper are relatively tranquil, and 

 like the upper slope, canyon floors are covered by silting sand. 



CANYON MORPHOLOGY, CURRENTS, AND SEDIMENT TRANSPORT 



The outer continental shelf and slope areas adjacent to and including 

 Oceanographer and Lydonia Canyons can be characterized in terms of sediment 

 transport and current strength. Areas of high sediment transport include the 

 eastern rims of both canyons and the axis of Oceanographer Canyon down to 750 

 m. Areas of moderate sediment transport include the walls of both canyons 

 and the mud-free interval of the upper slope swept by warm-core rings. Areas 

 of low net sediment transport include most of the head and axis of Lydonia 

 Canyon, the small canyons, and the continental slope below 300 m. 



The data from the southern slope of Georges Bank suggests that the 

 energetics of bottom currents found within the canyons are directly related to 

 the overall canyon morphology. Large, long canyons with deep mouths at the 

 shelf break (the 200-m isobath) and steep walls interact with the tidal flow 

 regime to strengthen the bidirectional currents within the axial area. 



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