EXTENT OF FOLDING AND SUBSEQUENT EROSION 455 



specimen has a height of 44 millimeters, a length of 31 millimeters, and 

 a thickness of 16 millimeters. This species is of the B. richmondensis 

 type, but differs from that species in its proportions, as well as in the 

 very sharp lateral angles. From B. prcecursa Ulrich of the Upper Mays- 

 ville of the Cincinnati region it differs in its proportion, the broader 

 frontal portion, which is more flattened, and the sharper lateral angles. 

 This species is abundant in the Bays sandstone of Big Walker Moun- 

 tain and has also been obtained from the Lower Bays on Clinch Moun- 

 tain. A specimen apparently identical with the Bays sandstone species 

 has been obtained from the Cincinnatian of Colby, Clarke County, Ken- 

 tucky. 



2. B. cf. radiata (Hall). Several fragments showing the more rounded 

 front, more distinct plications, and greater width of the species, occur 

 with the preceding. 



3. Orthodesma cf. canaliculatum Ulrich. Several specimens showing 

 form and strong muscular outline of this Upper Cincinnati shell. 



4. Modiolopsis cf. modiolaris. Internal molds apparently of this 

 species. 



5. Ptennea demissa Conrad, rare. 



6. Ischyrodonta cf. decipiens Ulrich. A specimen agreeing in form, 

 outline, and markings with this Eichmond species. 



7. Cymatonota ? sp. ? 



8. Whiteavesia sp. ? 



Altogether this fauna has a distinctly Eichmondian aspect, though it 

 has also some late Maysville elements. It must be borne in mind, how- 

 ever, that precise correlation between rocks of distinct facies purely by 

 fossil content is a hazardous undertaking. Different species occur with 

 different facies, and the range of species in a sandstone facies may differ 

 decidedly from the range of the same species in a limestone or shale 

 facies. The most that can be said in the present case is thai the fauna 

 decidedly supports the view derived from other facts, namely, lliat the 1 

 age of the Bays is late Maysville and Eichmond. 



The East Eiver Mountain section. — This was examined by me in the 

 Blucfield region. The first ledges met with in ascending the 1 mountain 

 on the Bethel cross-road from the north, above the typical Sevier shale, 

 is a heavy bedded, coarse sandstone, the individual masses 1 to 5 feel 

 thick, the color prevailingly white, though reddish in part. It is so coarse 

 for the most part that it is better described as a line quartz-pebble con- 

 glomerate. The pebbles are of white quartz, well rounded, varying in 

 diameter up to a fourth of an inch, though averaging only aboul an 

 eighth of an inch in diameter. Cross-bedding is well marked in this 



