492 



SHBPAUD 



[CHAP. 20 



4. East Coast U.S. (New England Type) Canyons 



Kiienen ( nir)3) has called attention to some differences between the Corsican 

 and Riviera-type canyons, which he called "ravines", and the east coast 

 canyons, which he called "New England type". Although the continental slope 

 off northeastern United States has been moderately well surveyed down to 

 1()(K) fm (1S30 m). the outer portion of the slope valleys are still known only 

 from s])oradic lines which were not well controlled in position. Furthermore, the 

 only well known contours of the canyons were those made by Veatch and Smith 

 (11)39), which have been widely criticized for their interpretative character. 



Fig. 12. Cross -sections of Hudson Submarine Canyon. Locations of the pi-ofiles are 

 indicated on the map. (After Heezen, Tharp and Ewing, 1959.) 



However, enough information is available from this survey and the sounding 

 lines of Lamont Geological Observatory to allow some generalizations. They 

 resemble those of the west coast of the United States and the Corsican canyons 

 in their V-shape, and in having occasional rock outcro])s on their walls. Their 

 gradients are similar to those of the west-coast canyons (Shepard and Beard, 

 1938) although they appear to lack any rock-walled gorges at their heads with 

 ])recipitous gradients. As Kuenen points out, the canyons differ also in extending 

 directly down the dip of the submarine slo])e with only minor bends. They have 

 far fewer major tributaries than found in the canyons previously described. 



Profiles of Hudson Canyon (Fig. 12) made by Lamont scientists (Heezen 

 et al., 1959) indicate that it changes from a gorge more than 5(>() fm (900 m) 

 deep to a channel only 50 fm (90 m) deep at the base of the continental slope, 



