May 1, 1896.] 



SCIENCE. 



651 



probably rests unconformably upon the 

 Kockwood. Above the Chattanooga are the 

 Fort Payne chert and Bangor limestone, 

 forming the lower Carboniferous, and the 

 Lookout and Walden sandstones, forming 

 the Coal Measures. Nearly all the forma- 

 tions exhibit an increase in thickness and 

 in proportion of sand and mud toward the 

 east, showing that the land from which 

 their materials were derived lay to the east 

 and southeast. 



The geologic structure is simple in the 

 region occupied by the plateaus, and com- 

 plicated in the valleys. In the Cumberland 

 Plateau the strata are almost perfectly hori- 

 zontal, while in Walden Ridge they have a 

 slight dip from the edges toward the center. 

 Sequatchie Valley is located upon the 

 westernmost of the sharp anticlines which 

 characterize the central division of the 

 Appalachian province. In the eastern part 

 of the district the strata have suffered com- 

 pression, which had forced the originally 

 horizontal strata into a series of long, narrow 

 folds whose axes extend in a northeast- 

 southwest direction. In addition to the 

 folding, and as a further effect of the com- 

 pression which produced it, the strata have 

 been fractured along many lines parallel 

 with the folds, and the rocks upon one side 

 — ^generally the eastern — -have been thrust 

 upward and across the broken edges of 

 those on the other side. A fault of this 

 character passes along the western side of 

 the Sequatchie Valley, and several forma- 

 tions which would normally occur there are 

 entirely concealed. 



Mineral resources. — These consist of coal, 

 iron ore, limestone, building stone, and brick 

 and tile clay. The productive coal-bearing 

 formations, the Lookout and Walden sand- 

 stones, occupy the surface of the plateaus. 

 They have an area within the district of 

 about 400 square miles, and contain from one 

 to three beds of workable coal. The beds in 

 the Lookout are generally variable in posi- 



tion, extent and thickness ; those in the Wal- 

 den are constant over large areas, and a^re 

 worked on a considerable scale at various 

 points along the eastern side of Walden 

 Ridge. About 200 square miles of area of 

 these upper coals occur within the district, 

 on the Cumberland Plateau and the eastern 

 half of Walden Ridge. The most important 

 iron ore in the district is the red fossil or 

 Clinton ore, which occurs as a regularly 

 stratified bed in the Rockwood shale. The 

 bed is from 3 to 5 feet thick in Sequat- 

 chie Valley, but considerably thinner in the 

 vicinity of Chattanooga and eastward. 



FOLIO B, SEWANEE, TENNESSEE, 1894. 



This folio consists of nearly four pages of 

 text, signed by Charles Willard Hayes, geol- 

 ogist ; a topographic sheet (scale 1: 125,- 

 000), a sheet of areal geology, one of eco- 

 nomic geology, one of structure sectiotis, and 

 one giving columnar sections. 



Geography. — The map is bounded by the 

 parallels 35° and 35° 30' and the meridians 

 85° 30' and 86°, and the territory it repre- 

 sents is wholly within Tennessee, embracing 

 portions of Grundie, Sequatchie, Marion, 

 Franklin and Coffee counties. The district 

 lies almost wholly within the western or 

 plateau division of the Appalachian prov- 

 ince. Crossing its southeastern corner is 

 the Sequatchie Valley, located upon the 

 westernmost of the sharp folds which char- 

 acterize the central or valley division of the 

 province. The larger part of the district is 

 occupied by the Cumberland Plateau, which 

 has a gradual ascent toward the north, 

 rising from an altitude of between 1,700 and 

 1,800 feet on the south to 1,900 or 2,000 feet 

 6n the north. The plateau is limited by a 

 steep escarpment from 1,100 to 1,500 feet in 

 height on the east and about 1,000 feet in 

 height on the west. Many streams have 

 cut their channels backward into the pla- 

 teau, forming deep, narrow coves, so that 

 the escarpment forms an extremely irregii- 



