July 10, 1896.] 



SCIENCE. 



37 



district is seen from an altitude of 1,000 

 feet or over, it appears as a broad undula- 

 ting plain, nearly all the ridges and hills 

 rising to a uniform level a little less than 

 1,000 feet in altitude. Above this level a 

 few ridges rise some hundreds of feet; be- 

 , low it the Tennessee and Hiwassee Kivers 

 flow in valleys 250 feet in depth. In other 

 words, this portion of the Appalachian Val- 

 ley may be regarded as a plain on which 

 the higher ridges remain in relief and in 

 which the stream channels have been sunk. 

 A similar plain, having an altitude of about 

 1,700 feet, stretches along the western base 

 of the Unaka chain. This is much more 

 deeply dissected by narrow stream channels 

 than the lower plain in the valley. These 

 are portions of the two principal peneplains 

 of the southern Appalachian province, 

 formed respectively in Tertiary and Creta- 

 ceous time. The greater part of the area 

 is drained by tributaries of the Hiwassee 

 Eiver, which crosses it in a direct course 

 and joins the Tennessee Eiver near the 

 western border. A small part is drained 

 by the Conasauga Eiver, whose waters flow 

 south to the Coosa and thence directly to 

 the Gulf. The divide between the drain- 

 age systems is broad and indistinct, and a 

 little below the lower of the two peneplains 

 of the region. From a study of this and 

 adjacent areas it appears probable that dur- 

 ing the formation of that peneplain the 

 drainage was very difierent from that at 

 the present time. Previous to the uplift 

 which caused the streams to cut their pres- 

 ent channels in the peneplain, the Tennes- 

 see Eiver did not turn westward, as it now 

 does, but continued southward in the val- 

 ley, across the present divide, directly to 

 the Gulf. 



The rocks of the Cleveland quarter- degree 

 fall into three groups : The Ocoee series, 

 the Chilhowee series, and the fossiliferous 

 Paleozoic formations of the Appalachian 

 Valley. Probably the oldest rocks in the 



region occur in its southeastern corner, 

 forming Big Frog Mountain and the plateau 

 along its western base. No fossils have yet 

 been found in these rocks, and they are 

 separated by a great fault from rocks of 

 known age, so that their position in the 

 stratigraphic column has not been fixed 

 with certainty. However, since they bear 

 all the marks of extreme age, and, so far as 

 known, contain no organic remains, they 

 will be considered Algonkian until satisfac- 

 tory evidence to the contrary is found. 

 They consist chiefly of graywacke slates, 

 containing many beds of coarse conglomer- 

 ate and some siliceous limestones. 



The Chilhowee series consists of quartz- 

 ites, sandstones, conglomerates and shales^ 

 which form Beans and Starrs Mountains at 

 the southeastern border of the valley. The 

 area of these rocks is separated by faults 

 both from the Ocoee on the east and the 

 fossiliferous valley formations on the west. 

 No fossils have yet been found by which 

 their age can be determined, but they cor- 

 respond so closely with a series of forma- 

 tions in the Chilhowee Mountains, in which 

 Cambrian fossils have been found, that 

 there can be little doubt that they occupy 

 the same stratigraphic position. 



The fossiliferous Paleozoic rocks of the 

 valley embrace three Cambrian formations, 

 made up largely of argillaceous and sandy 

 material. The Knox dolomite, which is 

 from 3,800 to 4,100 feet in thickness, is in 

 part Cambrian and in part Silurian. Above 

 this is the Chickamauga limestone, 1 ,000 feet 

 in thickness in the western part of the area, 

 and 300 or 400 feet thick in the eastern 

 part, where the upper portion of the lime- 

 stone is replaced by shales and sandstones, 

 forming the Athens, Tellico and Sevier 

 formations. Finally, above these, is the 

 Eockwood formation, which also shows 

 considerable increase in thickness and in 

 the proportion of coarse material toward 

 the southeast. The Devonian is repre- 



