Stevenson.] AoA {Zzji. 21, 



This division is easily recognized in middle Tennessee, but the distinction 

 is not so clear in eastern Tennessee. "So far as its presentation in East 

 Tennessee is concerned, no division is practicable." 



Within the area under consideration, the group is double. It is shown 

 in the gaps of Stone mountain and is well exposed near the North Fork of 

 Holston river along the line of the Bristol Narrow Gauge Railway Com- 

 pany. The section at Pennington's gap is : 



1. Cherty limestone , 200' 



2. Reddish silicious beds, some of them blue on fresh 



surface, some shale 150' 



The lower member was identified by Mr. Moore, who has visited this gap, 

 with the Protean member or the Knobstone of Kentucky. The limestone 

 is well exposed both here and in Big Stone gap, and at both localities it 

 contains much chert in nodules, sometimes as large as a melon. The 

 change in this group is as striking as that observed in the Mountain Lime- 

 stone group, and the section near the North Fork of Holston is as follows : 



1. Limestone and shale 655' 



2. Calcareous sandstone and shale 100' 



Several of the limestone beds hold very much chert, in layers and nodules, 

 but the quantity is comparatively small in the lower beds, one of which is 

 almost free from it. The lower member of the group consists of sky-blue 

 grits, breaking with irregular fracture, and some yellow shales in which is 

 a carbonaceous layer. The exposure is not wholly complete and between 

 30 and 40 feet of the upper part of the shale is concealed. The top layers 

 for about 10 feet are fairly well shown in the railroad side-cutting. A coal 

 bed may belong in the concealed interval as coal is said to have been digged 

 in the bed of the river almost directly opposite to this concealed space. 



The only trace of fossils found in the lower member was a fragment of 

 what seemed to be Leiorhynchus ; no Lithostrotion was seen in the upper 

 member, but Productus and Atliyris are common, as are also crinoid stems 

 and bryozoans. These may be collected either in Stone or in Brushy 

 mountain. The chert often replaces Productus. 



The Protean member of the Silicious group shows some interesting 

 variations ; Prof. Fontaine obtained the following section on the Green- 

 brier river of West Virginia : 



1. An upper member consisting almost entirely of red 



marlites 250' 



2. A middle member characterized by predominance of 



gray sandstones, containing coal 350' 



3. -A lower member, characterized by silicious sandstones 



and conglomerate. Thickness exposed, 60'. With 

 this should probably be counted 500' of under- 

 lying more silicious flags, total , 560' 



There is no room for doubting the identity of this section with the Protean 

 group, for Prof. Fontaine obtained Lithostrotion canadense from the lime- 



