SUBMERGED CANON AND FJORDS. 67 



from 900 to 1,200 feet above its floor. This valley is now submerged to a 

 depth of 3,000 feet, and is the representative of the channel of the ancient 

 Mississippi river, towards which it heads.* 



On the Pacific coast, in the region of Cape Mendocino, Prof. George 

 Davidson has identified three valleys now submerged to from 2,400 to 3,120 

 feet, and several of inferior depth. These measurements are those of the 

 valleys where they break through the marginal plateaus of the continent, 

 at about six miles from the present shore, where it is submerged to the depth 

 of a hundred fathoms, f 



The soundings along the Atlantic coast reveal similar deep fjords. The 

 long-since known extension of the Hudson river, beneath the Atlantic 

 waters, is traceable to the margin of the continental plateau, acquiring a 

 depth of 2,844 feet, in front of which the soundings show a bar, covered with 

 mud, which however is now submerged to the depth of only 1,230 feet. 

 The unpublished soundings off the mouth of the Delaware river bring to 

 light another valley, the floor of which is now covered by ocean waves to 

 nearly 1 ,200 feet — its continuation seaward not having been ascertained.! 



Were the continent elevated only 600 feet, the Gulf of Maine would be 

 replaced by a terrestrial plain, in some places 200 miles wide, but traversed 

 by rivers, one of which, towards its mouth, would be 2,064 feet deep — that is 

 to say, the bottom of the fjord is now submerged 2,664 feet. Even this 

 great depth may not be its maximum, for along the line between the oppo- 

 site banks, at the mouth, now beneath a hundred fathoms of water (which is 

 approximately the depth to which the real margin of the continent is sub. 

 merged), we find that the sea is nearly 5,000 feet deep. Whether this 

 represents an embayment of the ocean setting towards the valley or a con- 

 tinuation of the fjord is not determined. 



The St. Lawrence river and gulf bear the same testimony of the existence 

 of deep fjords extending from the rivers through the now submerged plateau 

 forming the margin of the continent ; and the lower part of Saguenay river 

 flows between stupendous walls and constitutes a fjord whose waters 

 reach a depth of 840 feet. In the St. Lawrence river, a little below 

 the mouth of the Saguenay, there is a channel 1,134 feet below the surface. 

 This increases in depth in passing seaward. In the region of the centre 

 of the modern gulf, the floor of the old channel is now submerged 1,878 

 feet, and the adjacent valley 1,230 feet; thus showing the canon as being 

 over 600 feet deeper. As at the mouth of the channel through the Gulf of 

 Maine, so at the mouth of that of the St. Lawrence, there is a deep chasm ; 

 for enclosed between the banks, a hundred fathoms below the surface, there 

 is now the depth of 3,666 feet, with water 2,000 feet deeper just seaward of 



* J. W. Spencer, " The Mississippi River During the Great River Age," New Haven, 1884, p. 2. 



fGeo. Davidson, Bull. Cal. Acad. Sc, Vol. II, 1887, p. 265. 



X Appendix 13, Rep. U. S. Coast and Geodetic Survey for 1887 (1889), pp. 270-73. 



