118 J. W.SPENCER — RECONSTRUCTION OF ANTILLEAN CONTINENT. 



in leveled sections. Near the coast the broad valleys are commonly 

 deeply buried, even to hundreds of feet. In the case of the Mississippi, 

 at New Orleans, a well to a depth of 900 feet below the surface did not 

 reach the floor of the old valley of erosion. To give a list of examples 

 would include all of the valleys of existing rivers and others now com- 

 pletely buried. These buried valleys are discovered by well borings, 

 and in other cases inferred by the forms of the vallej^s themselves, whose 

 outlines are not completely obliterated. 



Analogy between the submerged Valleys or Fjords and the land 

 Valleys and Canyons, with Inferences as to former continental 

 Development. 



When the valleys of the southern Appalachian mountains, whether 

 two, four, twenty or forty miles wide, are compared with the sub- 

 merged Antillean depressions the resemblance is complete. Even the 

 embayments into the continental plateaus, characteristic of the expanded 

 mouths of the fjords, are no greater than the present embouchures of 

 many rivers or their flood-plains. The only difficulty in accepting these 

 drowned valleys as those of the former land depressions is the great dei3th 

 to which they reach. AVhere the soundings are numerous, as they are 

 in some localities, the submarine contours show the drowned valleys 

 continuously from where the surface coastal currents cease to act to the 

 greatest depths. Again, tliese flooded valleys terminate in broad embay- 

 ments, which are greatest where several fjords leave the plateau together, 

 just as the divides between the neighboring rivers are gradually reduced 

 beneath the general level of the plateau, owing to the double denudation 

 on both sides of the ridges. 



The submerged valleys have their tributaries coming from different 

 directions, as is the case with rivers. In some places the fjords have 

 steep walls, while again they are V-shaped or broader valleys, a few miles 

 wide. The direction in relation to the mountains is at every angle, but 

 the prevailing systems are at right angles to the mountain ranges of the 

 land, and accordingly the depressions are not mountain folds. Two or 

 three fjords are parallel to the mountain folds, and may have been deep- 

 ened by the movements of an erogenic nature. The valleys commonly 

 cross coastal plains of undisturbed strata, which largely belong to the 

 later geologic formations. All of the drowned valleys are connections or 

 continuations of the rivers of the continents or islands. The fjords are 

 recognizable for distances from 50 to 250 miles, and in one case for 600 

 miles.* 



* See foot-note, p. 140. 



