PHYSIOGRAPHY 527 



meandering in its sluggish course across this ancient land (the fore- 

 runner of the present Tennessee) were large marshy, swamp areas cov- 

 ered with dense plant growth. In this area, along the eastern base of 

 this ridge, occurred many springs, bringing up large quantities of water 

 charged with mineral salts^ which quickly precipitated on coming in 

 contact with the acid swamp waters and bacterial life of this old geologic 

 plain. 



Watson* states that "the formation of this plain was probably during^ 

 Eocene time. ... In this event they [the bauxite deposits] must 

 have been formed near the close of the joeriod of the Eocene baseleveling.'' 



The peneplain of which the top of White Oak Mountain is a remnant 

 is capped by Mississippian rock and very probably is an isolated eastern 

 remnant of the Highland Rim peneplain of Middle Tennessee, which on 

 the western side of Middle Tennessee is covered by upper Cretaceous 

 gravel of the Tuscaloosa formation. 



Along the western edge of the White Oak Mountain-Highland Eim 

 peneplain are a number of well defined terraces along the Tennessee 

 River. The terraces have been described by Wacle,^ who distinguishes six 

 ■distinct terraces below the top of the White Oak Mountain-Highland 

 Rim peneplain, occurring at approximately 780-800 feet, 620-700 feet. 

 600 feet, 500 feet, 420 feet, and 380 feet, the last being about 10 feet 

 above the floodplain of the present Tennessee River, and considers the 

 Tipper two terraces, occurring at 780-800 and at 620-700 feet^ to be of 

 Pliocene age, while the terraces occurring at 600 feet and lower he re- 

 gards as of Pleistocene age. These terraces should tie into peneplains 

 formed during those periods, and it is considered that the peneplain on 

 which the bauxite deposits at Chattanooga were formed, and which occurs 

 approximately 450 feet below the top of the White Oak Mountain-High- 

 land Rim peneplain at East Chattanooga, corresponds in age to the river 

 terrace occurring at 600 feet elevation, mentioned above by Wade as 

 having been formed at the beginning of the Pleistocene period. This 

 terrace occurs approximately 450 feet below the AATiite Oak Mountain- 

 Highland Rim peneplain. 



In this connection it is interesting to compare the table of terraces of 

 the Pleistocene and upper Pliocene periods, prepared by Osborn and 

 Reeds,® with the above conclusions. Their highest river terraces, stated 



* Thos. L. Watson : Georgia Geological Survey, Bull. 11, 1904, p. 130. 



^ Bruce Wade : Gravels of West Tennessee Valley. Tennessee Geol. Survey. Rec. of 

 Tennessee, vol. 7, 1917, pp. 55-90. 



6 H. F. Osborn and C. A. Reeds: Old and new standards of Pleistocene division in 

 relation to the prehistory of man in Europe. Bull. Geol. Soc. Am., vol. 33, no. 3, 1922, 

 fig. 13, pp. 411-490. 



