PEEGLACIAL ELEVATION SHOWN BY FJORDS. 503 



3,000 feet; and it is iinj)ortant to note in passino- that an e(|ual uplift would 

 wholly close the Strait of Florida, 2,064 to 3,000 feet deep, through which 

 the Gulf Stream now pours into the North Atlantic. 



The continuation of the Hudson River Valley has been traced bj" 

 detailed hydrographic surveys to the edge of the steep continental slope at 

 a distance of about 105 miles from Sandy Hook. Its outermost 25 miles 

 are a submarine fjord 3 miles wide and from !)00 to 2,250 feet in vertical 

 depth, measured fi-om the crests of its banks, which, with the adjoining flat 

 area, decline from 300 to 600 feet lielow the present sea-level. The deepest 

 sounding in this fjord is 2,844 feet.^ 



In a similar position, just inside the bathymelrie line of 100 fathoms 

 on the submerged margin of the continental plateau off" the mouth of Dela- 

 ware Bay, the Coast Survey soundings reveal a short fjord which has a 

 depth of 396 fathoms, or 2,376 feet.^ 



Again, the United States Coast Survey and British Admiralty charts, 

 as Spencer states, record submerged fjord outlets from the Gulf of Maine, 

 the Gulf of St. Lawrence, and Hudson Bay, respectively, 2,664 feet, 3,666 

 feet, and 2,040 feet below sea-level. The bed of the old Laurentian River 

 from the outer boundary of the Fishing Banks to the mouth of the Saguenay, 

 a distance of more than 800 miles, shown by Professor Spencer's map, is 

 reached by soundings 1,878 to 1,104 feet in depth. 



Greenland is divided from the contiguous Noi-th American continent 

 and archipelago by a great valley of erosion which is estimated from sound- 

 ings and tidal records to have a mean depth of 2,510 feet below sea-level 

 for 680 miles through Davis Strait, 2,095 feet for 770 miles next northward 

 tlii-ough Baffin Bay, and 1,663 feet for the next 55 miles north through 

 Smith Strait.' 



On the Pacific coast of the United States Prof. Joseph Le Conte has 

 shown that the islands south of Santa Barbara and Los Angeles, now sepa- 

 rated from the mainland and from each other by channels 20 to 30 miles 



'A. Lindenlvolil, Report of U. S. Coast and Geodetic Survey, for 1884, pp. 4.35-438; Am. .lour. Sci. 

 {3), Vol. XXIX, pp. 475-480, .June, 1885, and Vol. XLI, pp. 489-499, with raa)>, .Tune, 1891. J. D. Dana, 

 Am. Jour. Sci. (3), Vol. XL, pp. 12.5-437, Dec, 1890, with map reduced from U, S. Coast Survey chart. 



-A. Lindenkohl, Am. .lour. Sci. (3), Vol, XLI, p. 498. 



' Smitbsouian Contributions to Knowledge, Vol. XV, pp. 163, 164. 



