528 W. A. XELSOX APPALACHIAX BAUXITE DEPOSITS 



to have been formed at the beginning of the Pleistocene period, are shown 

 to occur at 90 to 100 meters above existing beds of large rivers, which 

 checks in roughly with the 600-foot Tennessee River terrace discussed 

 above, as it occurs approximately 260 feet above the Tennessee Eiver. 

 Osborn and Reeds consider this to have been the period of Xebraskan 

 glaciation. 



It is considered that the bauxite deposits of the Chattanooga district 

 were formed at a much later date than the Eocene, and that one is justi- 

 fied on the basis of the above correlation of tentatively placing their age 

 as of early Pleistocene. Following the close of this baseleveling period 

 came an upward warping of the earth's crust, and this Highland Rim- 

 White Oak Mountain peneplain was uplifted and tilted upward toward 

 the east, so that at the foot of the Cumberland Plateau this peneplain 

 has only an elevation of 1,000 feet as against the elevation of 1,300 feet 

 of the White Oak Mountain, or a progressive uplift toward the east of 

 300 feet. This upward movement, which probably started gradually 

 during the Pliocene or at the beginning of Pleistocene time, with a tilt- 

 ing upward of the rocks to the east, naturally caused a migration of the 

 streams flowing on this old peneplain to the western side of whatever 

 valleys they occupied, and in this particular valley between Missionary 

 Ridge and AYhite Oak Mountain caused a shifting of the stream up close 

 to the eastern base of Missionary Ridge and the location of river swamp 

 areas in this particular region. 



A study of the Xalbfleisch bauxite mines in this region shows lying 

 to the west of the bauxite deposits and contiguous to it a deposit of dark 

 brown lignite and lignitic cla}', which was measured where exposed as 

 being 36 feet long and having a maximum thickness of 25 feet. The 

 presence of this lignite deposit in connection with the bauxite ore shows 

 very clearly that this ore was formed on an old peneplain which now has 

 an approximate elevation of 850 feet, and that the bauxite was formed 

 in an area where swamp conditions existed suitable for peat formation 

 and deposition and where the surface waters were of the acid swamp- 

 water type, full of tannic and humic acids. 



Geology 



Starting at Bragg's quarry, in East Chattanooga, and going ujd the 

 west side of Missionary Ridge, one finds an excellent section, beginning 

 at the base of the Lowville formation of the Black River group, of Ordo- 

 vician age (in which the bentonite occurs), and extending up into the 

 red shales and limestones of the Rockwood formation, of Silurian age. 



