762 ABSTRACTS 



sandstones, occupy the upper portions of Pigeon, Lookout and Sand 

 mountains, having an area in this district of 116 square miles. The 

 Lookout generally contains one, and in some places two or three, 

 workable coal seams, but they are variable in position, extent, and 

 thickness. The Walden sandstone forms a considerable area on Look- 

 out Mountain, and contains at least one valuable seam of coal, which 

 is extensively worked at the Durham mines. Two varieties of iron ore 

 are found in workable quantities. The first is the red fossil or "Clin- 

 ton" ore, which occurs as a regularly stratified bed in the Rockwood 

 formation, and is worked at various places along the base of Lookout 

 Mountain. The second variety is limonite, which occurs as a pocket 

 deposit at the base of several of the ridges along the eastern border of 

 the district. Associated with the latter, particularly along the faults, 

 are deposits of manganese, generally as nodules scattered through the 

 surface soil. 



Geologic Atlas of the United States. Folio ^, Kingston, Tennessee, 

 1894. ■ 



This folio consists of three and one-half pages of text, signed by 

 C. Willard Hayes, geologist; a topographic sheet (scale i : 125,000), 

 a sheet of areal geology, one of economic geology, one of structure 

 sections, and one giving columnar sections. 



Geography. — The map is bounded by the parallels 35° 30' and 36°, 

 and the meridians 84° 30' and 85°. The district represented lines 

 wholly within the state of Tennessee, and includes portions of Cum- 

 berland, Morgan, Roane, Rhea, Loudon, Meigs, and McMinn counties. 

 Its area is approximately 1000 square miles, and it forms a part of the 

 Appalachian province, being about equally divided between the valley 

 and plateau divisions of the province. The northwestern half of the 

 district is a portion of the Cumberland Plateau. The surface of this 

 half, except in the Crab Orchard Mountains, is comparatively level 

 and has an altitude of between 1800 and 1900 feet. Its streams flow 

 in shallow channels until near the edge of the plateau, when they 

 plunge into rocky gorges which form deep notches in the escarpment. 

 The Crab Orchard Mountains are formed by the uneroded portions of 

 an anticline, the hard bed rising in the form of a low arch. Toward 

 the southwest the hard beds were lifted higher, and have been removed, 

 exposing the easily erodible limestone beneath, and in this the Sequat- 

 chie Valley has been excavated. The southeastern half of the district 



