Apeil 25, 1902.] 



SCIENCE. 



671 



(1) Many of the more important valleys 

 stop abruptly at or near the shore line, and no 

 ■corresponding valley or depression exists on 

 the land, so far as known; nor (2) are there, 

 except in a very few instances, corresponding 

 embayments in the coast line, as there should 

 be if the valleys are of comparatively late 

 origin, and especially if developed subse- 

 quent to the formation of the 'continental 

 shelf (submarine platform). 



(3) The submarine platform, except in one 

 or two places, shows nothing that could be in- 

 terpreted as warping in their neighborhood, as 



responding submarine channels. (2) Where 

 they are opposite important valleys on the 

 shore, the submarine valleys do not correspond 

 to them in size, shape or grade. (3) The 

 submarine platform, in the case of many 

 of the more important valleys, has not 

 been developed through cutting between the 

 head of the valley and the shore, nor have the 

 heads of the valleys been filled in with sedi- 

 ments, even in regions of deposition. Two of 

 the valleys head near the points of cuspate 

 forelands, the valleys, in both instances, run- 

 ning in close to the beach. A third valley 



A. Section across (1) Cape Mendocino and (2) Punta Corda submarine valleys, where the valley 

 bottom of the former has a depth of 2,000 feet, and of the latter a depth of 2,400 feet. 



B. Section across Vincente submarine valley, where the valley bottom has a depth of 1,500 feet.- 



C. Profile of Vincente submarine valley and of the mainland along the same general line. Verti- 

 cal scale in C five times horizontal. 



it should if they were of subsequent develop- 

 ment. (4) On the other hand, imless the val- 

 leys belong to the very latest stage of coastal 

 development, the submarine platform should 

 be developed between the head of the valley 

 and the shore, or the head of the valley 

 should be filled with shore detritus. This is 

 not the case with most of the valleys. 



(5) The objection raised by Fairbanks that 

 their course is transverse to the principal 

 structural lines of the coast, appears to the 

 present writer to have little weight, since 

 minor structural lines might occur at any 

 angle with the main lines. 



The interpretation as submerged stream val- 

 leys is also unsatisfactory because: (1) The 

 submarine valleys do not, in general, corre- 

 spond in position to valley openings on the 

 shore, and, vice versa, the coast drainage lines 

 (except in a very few instances) have no cor- 



heads near a form having the general appear- 

 ance of a blunt cusp. If the submarine val- 

 leys were developed prior to the formation of 

 the platform, they would have been modified 

 by its development; if subsequently developed 

 (as stream valleys), it should be possible to 

 trace them inland, and there should be cor- 

 responding embayments in the coast line. 



In view of the fact that so many of the 

 valleys (about one-half) stop abruptly close to 

 the present shore line, it would hardly seem 

 that this could be accidental, and the reason 

 for it is the critical point in attempting an 

 explanation of the valleys. This fact, to- 

 gether with the other objections given above, 

 would point to the conclusion that some of the 

 valleys at least must be wholly or partly due 

 to present causes. The only cause capable of 

 producing such results — keeping the valley 

 head open close to shore in the face of active 



