TENNESSRE AND ADJOINING DISTRICTS. 75 



conditions, namely hard grits or sandstones resting on soft strata, 

 and these occupying the line of a low synclinal axis, ranging in a 

 N.E. and S.W. direction. The strata in this position being the 

 latest which were upraised, were preserved almost intact; while 

 those continuous with them, and forming the flanks of the parallel 

 anticline, were denuded away. The simple conditions here stated 

 are somewhat modified by the two secondary anticlines along the 

 Sequachec Valleys; but these do not affect the general position, and 

 are themselves examples of lesser valleys eroded along anticlinal 

 axes. 



It should also be observed that the Tennessee Eiver, continued 

 into the Clinch Eiver, keeps close to the base of the escarpment of 

 the Cumberland Plateau (Waldeu's Eidge) ; and we may suppose 

 that, as this escarpment was cut back in the direction of the dip, 

 the river itself gradually moved westward, or in the same direction*. 

 Thus the Cumberland Plateau was developed by the erosion of the 

 Valley of East Tennessee on the one hand, and by a somewhat 

 similar series of physical operations along the Valley of the Cumber- 

 land Eiver on the other or western side. 



II. The Gorge of the Tennessee throur/h the Ciunherland Plateau. 



The course of this stream, the fourth in size in the United States, 

 is most remarkable, and requires to be explained on geological prin- 

 ciples. Descending (under the name of the Little Tennessee) from 

 the Blue Eidge (or Archaean Protaxis), it crosses the Unaka ridge 

 in a north-westerly direction to Kingston ; here it joins the Clinch 

 Eiver. coming down the Shenandoah Valley in a south-westerly 

 direction ; and this course it retains, flowing along the foot of the 

 Cumberland Plateau to Chattanooga, when it changes its course, and 

 traverses the plateau by the gorge already described. Ultimately 

 the Tennessee, instead of continuing its course in a southerly direction 

 into the Gulf of Mexico, makes a great sweep to the northward and 

 joins the Ohio at a distance of about forty miles above the junction 

 of that river with the Mississippi, thus adding to its course a length 

 of about 800 miles ! 



The east and west saddle or water-parting, from which the streams 

 drain into the Tennessee on the one side and into the Gulf of Mexico 

 on the other, descends to a level of about 920 feet above the waters 

 of the Gulf a few miles south of Chattanooga. The level of the 

 saddle is only 270-280 feet above the river at Chattanooga ; so that 

 (to put the case in popular language) we may say that the Tennessee, 

 rather than take a direct course towards the Gulf by crossing a saddle 

 which is only 270-280 fee]t above its bed, has preferred a channel 

 through a table-land rising 1400-1500 feet above its bed — a course 



* If we regard the direction, the Tennessee River is the real continuation of 

 the Cliucli downwards, and the Little Tennessee is a lateral tributary. The 

 Tennessee at a foruaer period probably ran in a channel further east and at a 

 higher level. 



