Moderate size canyons with shallower mouths and less steep walls have weaker 

 bidirectional flows. Small shallow canyons and gullies are low energy 

 depositional environments. Because sediment transport and bottom facies are 

 generally well -correlated with current energy, the results from studies of 

 Lydonia, Oceanographer, and other canyons can be used to predict bottom 

 facies, sediment transport regimes, and depositional vs. erosional areas for 

 other canyons on the southern margin of Georges Bank (Table 1). High energy 

 canyons include Oceanographer, Hydrographer, and Gilbert. Moderate energy 

 canyons are Lydonia, Powell, Welker, and Veatch. Low energy canyons include 

 Atlantis and Heeltapper. 



In general, sediment movement is more rapid in a narrow band along the 

 upper slope, along the lower walls and floors of large, high-energy canyons, 

 and from the shelf westward across the eastern rims of large and medium 

 canyons. Sediment movement is less rapid on the outer shelf, on most of the 

 upper slope, including the gullies, on the floors of medium and small canyons, 

 and on the shelf around some canyon heads. A moderately energetic canyon of 

 medium size such as Lydonia may be accumulating sediment most rapidly. The 

 movement and resuspension of fine-grained sediment on the floor of Lydonia 

 Canyon is substantial. However, the canyon traps a large volume of shelf sand 

 as well as bioeroded silt from outcrops on lower canyon walls, and sediment is 

 accumulating on its floor. 



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