1831.] -<i45 [Stevenson. 



Wallerti's Ridge and Valley. 



At Turkey cove, the limestones of III rise high up on the side of Wal- 

 len's ridge, but the shales belonging at the top of the group are concealed 

 along the road crossing the ridge. Further west, however, as the ridge is 

 pushed away toward the south-east, the limestones reach only to its foot or 

 to but a little way up its side. The shales are well shown along the Jones- 

 ville and Estillville road as it winds up the mountain. They are dark 

 and fissile below but become somewhat sandy above. Thin irregular bands 

 of limestone occur, all of which are fossiliferous. The thickness of the 

 shales is not far from 700 feet. 



The Medina sandstone is reached at the summit of the ridge, where, for 

 the most part, it is fine grained and compact ; but it contains some layers 

 of shale and an occasional bed of conglomerate. Exposures are incom- 

 plete near the road, but the rock forms cliffs at two or three miles further 

 east. The thickness, as estimated, is not far from 350 feet. The Clinton 

 group is reached on the southerly side, where it is not well exposed. The 

 fossil ores are shown at several places, but are best seen near the head of 

 the valley, where Mr. Jerome Duft has explored them to a slight extent. 

 The Lower Helderberg rocks are mostly concealed. 



The Wallen Valley fault passes very near the southerly foot of Wallen's 

 ridge, and is crossed by the Jonesville road at perhaps three-fourths of a 

 mile from Wallen's creek. The exposures near the line of fault are very 

 poor, but they suflice to show that the beds in contact with those of the 

 Lower Helderberg belong near the top of the Knox group, for the soil has 

 a deep red color and fragments of chert are scattered through it. The first 

 satisfactory exposures are those of the Trenton and Nashville group, whose 

 beds are well shown at Stickleyville and elsewhere along Wallen's creek. 

 They are very fossiliferous, though the number of species found at Stick- 

 leyville is small. The following were seen : 



Stromatopora ; Chcetetes petropoliiana ; Bryosoans ; Sir ophomena alter - 

 nata ; Leptcena sericea ; Orthis testudinaria ; OrtMs occidentalis ; Orthis 

 tricenaria f. The ChcBtetes is often replaced by chert, as is also the case on 

 the northerly side of Elk Knob in Powell valley. 



The limestones of this group continue nearly half way up Powell moun- 

 tain, and, thence to the summit, the shales of the group, are occasionally 

 shown. The Medina sandstone is reached at the summit, where one looks 

 down into the area drained by Clinch river. 



As the Wallen valley fault disappears north-eastward, the outcroppings 

 of Upper Silurian on the southerly slopes of Wallen's ridge and Powell 

 mountain approach each other ; and on the easterly face of the divide be- 

 tween Wallen's creek and the North Fork of Clinch, the two outcrops seem 

 to have come together, as do the similar outcrops on Wallen's and Poor 

 Valley ridges, where the fault of the latter dies out. No detailed examina- 

 tion of this divide was made, and the structure was ascertained only in so 

 far as was possible in passing through Slemp's gap. 



