36 



SCIENCE. 



[N. S. Vol. IV. No. 80. 



teau. Thus there is seen to be a close re- 

 lation in this region between structure and 

 topography. The valleys are located upon 

 the anticlines and the plateaus coincide 

 with the synclines. This relation depends 

 upon the relation of hard and soft rocks in 

 this region. Of the strata exposed, the up- 

 per formations are hard sandstones and the 

 lower generally limestones. After the anti- 

 clinal folds had been produced by lateral 

 pressure the region was for a long time sub- 

 jected to subaereal erosion. The whole sur- 

 face was reduced to a nearly uniform plain, 

 now represented by the summits of the 

 plateaus, but then near sea level. Thus 

 the hard sandstone was removed from the 

 tops of the arches, and when the region was 

 elevated the softer limestones there exposed 

 were easily reduced to the lower level, 

 while the surface within the synclines was 

 protected from erosion by the hard sand- 

 stones. 



The oldest formation of the region is the 

 Knox dolomite, which is brought to light 

 along the axes of the anticlines. Above 

 this is the Chickamauga limestone, from 

 1,100 to 1,400 feet in thickness, and the 

 Rockwood, which is here a calcareous shale. 

 The Devonian is represented by black, car- 

 bonaceous shale from 20 to 40 feet in thick- 

 ness, and the Carboniferous by Fort Payne 

 chert and Bangor limestone, representa- 

 tives of the Mississippian series, and the 

 Lookout and Walden sandstones, forming 

 the coal measures. In all about 5,000 feet 

 of strata are exposed, and the formations 

 generally thicken toward the southeast. 



The structure of the region is quite sim- 

 ple, and has already been indicated. In 

 addition to the anticlines which were 

 mentioned, there is a fault along the west- 

 ern side of the Sequatchie anticline which 

 brings the Knox dolomite in contact with 

 the Bangor limestone for several miles. 



The principal mineral resources of the 

 region are coal and iron ore, while lime- 



stone, building and roadstone and brick and 

 tile clay are subordinate but important. 

 The coal-bearing formations are the Look- 

 out and Walden. They occupy the surface 

 of the plateaus, forming 544 square miles, 

 the larger portion of which probably con- 

 tains workable coal. The only important 

 development of the coal is in Dade county, 

 Georgia, where five beds occur below the 

 conglomerate, at least four of which are 

 workable locally. The chief iron ore of the 

 region is red hematite or fossil ore of the 

 Eockwood formation. This ore is very 

 similar in appearance to that occurring at 

 the same horizon in such widely separated 

 localities as Wisconsin, 'S&w York and 

 central Alabama. It has been extensively 

 worked in the vicinity of Rising Fawn, 

 near the Georgia- Alabama line. It is not 

 always of workable thickness, but the 

 economic map shows the areas within 

 which it may be found. 



FOLIO 20, CLEVELAND, TENNESSEE, 1895. 



This folio, by Charles Willard Hayes, 

 embraces 4 pages of text, a sheet showing 

 topography, another areal geology, and a 

 third economic geology, also a sheet con- 

 taining five structure sections, and, finally, 

 a sheet giving two generalized stratigraphic 

 sections. 



The Cleveland quarter- degree is bounded 

 by the parallels 35° and 35° 30' and the 

 meridians 84° 30' and 85°. It contains 

 975 square miles, including portions of 

 Meigs, McMinn, James, Bradley and Polk 

 counties. The country represented on the 

 Cleveland sheet lies largely in the Appa- 

 lachian valley. Its northern corner reaches 

 within two miles of the Cumberland escarp- 

 ment, which forms the western limit of the 

 valley district, while its southeastern cor- 

 ner reaches beyond the limit of the valley, 

 and includes a small portion of the Unaka 

 Mountains, which form the western chain 

 of the Appalachians. When the valley 



