FJORDS OF THE GULF OF MEXICO. 113 



not everywhere siifiiciently numerous to work out the details. Among 

 the Bahamas the Exuman depression increases to a de[)t]i of over 6,000 

 feet, and may beh)ng to the same grou}) of drowned vaUeys as those 

 already described, or possibly to those parallel to the mountain folds of 

 the Great Antilles; still it is 250 miles distant from any mountains. 



In tlie gulf of Mexico the similar submerged valleys exist, and their 

 interpretation has been confirmed by recent studies of the writer, in 

 which evidence has been found of several old valleys, now somewhat 

 filled in their lower reaches. This has led to investigation of the char- 

 acter of the depressions, which in turn has bound together in indissolv- 

 able union the existing land valleys and the submerged fjords. Thus 

 the drainage of southern Florida flowed by Key West, and the channel 

 is recognizable near that key at a depth of 2,400 feet, where the adjacent 

 submerged land is only 840 feet below tide. With rocky banks of 600 

 feet in height, it is still apparent at a depth of 5,600 feet, and just bey olid 

 it joins the great Floridian fjord. On the western side of the Floridian 

 mass the Tampan, Suwaneean, Apalachicolan and other fjords all in- 

 cise the rapidly descending continental margin to a depth of over 10,000 

 feet. 



The Apalachicolan, Escambian, Mobilan and Mississippian fjords all 

 unite to form the great Mississippi embay ment of 9,000 feet in depth, 

 and where deeper the basin becomes a channel-like depression, increas- 

 ing to 12,000 feet, or about the full depth of the Mexican gulf. The Apa- 

 lachicola represents a broad valley extending far up into the Appalachian 

 mountains, and so do the Escambia and Mobile rivers — all the valleys 

 being several miles wide. Even in its upper portion the Mobilan fjord 

 has a depth of 700 feet, and the shelf which it crosses is itself submerged 

 to 1,500 feet. The Escambian fjord shows a depth of 1,800 feet beneath 

 its walls, which are 1,200 feet below tide level. All these drowned valleys 

 are recognizable in the soundings to a depth of over 10,000 feet. West 

 of the Mississii)pi there are other fjords which are apparently not con- 

 nected with tlie greater drainage of the modern rivers. One of these 

 indicates that during one of the j)eriods of elevation the Mississippi 

 made another channel west of tlie i)resent one. The Red River canyon 

 was also independent l^efore it united witli the Mississippi on its i)resent 

 iiood-phiin, which is from 30 to 80 miles wide. Again, the rivers enter- 

 ing the northwestern region of the gulf have continued seaward, to form 

 fjords and other embayments. Thus in front of the Rio ( Jrande drowned 

 valleys are recognizable, descending from ai)out (v){) feet to 8,280 feet, 

 where the sides of the valley rise 3,000 feet above the bottom of the de- 

 pression. Although the soundings are sometimes scattered, there are 

 enough to indicate these depressions with clearness, and the occurrence 



