CONTINENTAL TERRACES AND SUBMARINE VALLEYS II7 



The original large-scale maps are not easily reproduced as 

 book illustrations, but excerpts serve well to suggest the im- 

 pressive ruggedness of the 400-mile belt. Figure 63 is such a 



FIGURE 6$. MAP OF THE HUDSON CANYON AND VICINITY. CONTOUR- 

 INTERVAL 25 FATHOMS (150 FEET). 



reduced copy of a small part of one of the maps, the part 

 covering merely the head of the Hudson Canyon and vicinity. 

 Note the scale. This canyon heads 17 miles inside the hundred- 

 fathom line. Its over-all charted length is 50 miles; the actual 

 length is at least 20 miles greater. The vertical interval (contour- 

 interval) between successive isobaths below that of 100 fathoms 

 is 25 fathoms, or 150 feet. From the crowding of the contours, 

 with the large contour-interval chosen, one can see how mag- 

 nificent is the Hudson Canyon. 



Excerpt maps, again much reduced in scale, represent the 

 local areas covered by the Wilmington, Washington, and Nor- 

 folk canyons, and appear as Figures 64, 65, and 66 respectively. 

 For comparison a principal canyon in Georges Bank is shown 

 in Figure 67. 



