96 



INDEX TO THE STRATIGRAPHY OF NORTH AMERICA. 



Generalized section of the sedimentary rocks of tJie Roan Mountain quadrangle in the vicinity of 



Erwin.*^* 



System. 



Formation. 



Thickness 

 (feet). 



Character of rocks. 



o 



Athens shale. 



800-1,600 



Black and bluish-black calcareous shale below, blue-gray 

 banded slaty shale above. 



Knox dolomite. 



Nolichucky shale. 



3,000-3,700 



Magnesian limestone, light and dark blue, white, and gray, 

 with nodules and layers of chert and a few beds of calca- 

 reous sandstone. 



50-600 



Yellow, green, and brown calcareous shale with limestone 

 beds. 



Honaker limestone. 



Watauga shale. 



o o 



t^i 





ol 



Shady limestone. 



Hesse quartzite. 



Mun'ay slate. 



Nebo quartzite. 



Nichols slate. 



1,800-2,200 



Massive dark-blue and dark-gray limestone. White and 

 blue limestones. 



1,000-1,100 



Purplish, red, green, and variegated shales, sandy shales, 

 and thin sandstones, with calcareous shales and thin blue 

 limestones interbedded. 



750-1,000 



Gray, bluish-"ray, mottled-gray, and white limestone, with 

 nodules and masses of chert. 



700-1,000 



Massive white quartzite and sandstones. 



300-400 



Bluish-gray to gray argillaceous and sandy shale and slate, 

 with thin sandstone seams. 



200-900 



Massive white quartzite and sandstone, coarse and fine, with 

 layers of sandy shale, slate, and reddish sandstone. 



400-700 



Bluish-gray to gray argillaceous and sandy shale and slate, 

 with thin sandstone layers. 



Cochran conglomerate. 



Hiwassee slate. 



200-1,600 



Massive quartzite, sandstone, and conglomerate, white or 

 gray, with seams of dark slate. . 



300-1,500 



Bluish-gray to black and banded slates, with a little fine mica 

 schist. Includes layers of sandstone and conglomerate. 



Snowbird formation (amygda- 

 loid). 



700-2,000 



Gray and white feldspathic quartzite and sandstone, with 

 dark slate beds and lentils of amygdaloid. Locally be- 

 comes conglomerate and dark-purplish sandstone. Fine 

 quartz conglomerate and arkose at case. 





Granites. 



