EXTENT OF FOLDING AND SUBSEQUENT EROSION 451 



thin, greenish shales and some sandstones, which have a total thickness 

 of about 300 feet. The highest bed of the series is a soft fire-clay, which 

 is succeeded by the Chattanooga black shale. Summarizing this section, 

 we have the following: 



13. Chattanooga black shale. Feet Feet 



12. (Great hiatus and disconf ormity. ) 



11. Greenish shales and sandstones with a terminal bed of tire 



clay, Rockwood formation 300 



10. Rockwood fossiliferous iron ore and associated rocks 20 



9. Thin-bedded sandstone mostly concealed, probably Rockwood. 200 



Total Rockwood 520 



8. Red clays with included thin greenish or red limestone bands, 



the latter showing mud cracks, mostly covered 200 



7. Deep brick-red clays with occasional sandstones; no fossils. . 40 



6. Variegated clays mostly covered 105 



5. Sandy reddish clays and shales 15 



Total Bays 360 ± 



4. Reddish, greenish, and grayish shales with numerous upper 



Ordovicic fossils representing late Lorraine age 130 



3. Covered interval, soft shales, thickness estimated 300 



2. Thin clay shales, partly covered, estimated 10 



Total Sevier shales 440 



1. Chickamauga limestone. 



There is here a perfect gradation from the Sevier, witli its Upper Lor- 

 raine fossils into the unfossiliferous Bays. This latter is mainly a clay 

 shale, though calcareous beds are not wanting. There is no way of esti- 

 mating the original thickness of this formation, nor is it known if the 

 Clinch sandstone ever extended so far to the northwest. One would think 

 it likely that this was the case, hut proof for this is wanting. 



The Bays Mountain anticline sinks out of sight after entering Sullivan 

 County, Tennessee, a few miles below the Virginia State line, hut a 

 second pronounced monocline occurs io the north of it, punning from 

 Tennessee into Virginia. This is Clinch Mountain, the top of which is 

 formed by the Clinch sandstone. The Bays sandstone just underlies it, 

 bill seems to he somewhat thinner in this mountain than it is farther 

 north, due no doubt to unequal erosion. In the section along the road 



leading across (his mountain above Mendota, Virginia (Bristol quad- 

 rangle), the contact between the Ba \ s and the underlying Sevier is well 



shown on (he north of the monocline. Mere I found the following sec- 

 tion exposed in the summer of L906. The beds dip at a \<t\ uniform 



