1873.] 



159 



[Lesley. 



There is a small sharply-pinched synclinal (trough) of limestone VI, 

 between Black Oak Ridge and the foot of the mountain south of St, 

 Clairsville. This Upper Silurian limestone basin is less than 150 yards 

 across. 



Black Oak Ridge is about 200 feet high above the brook at its foot, At 

 its north end near St. Clairsville the Oriskany Sandstone VII forms its 

 backbone ; the black slates of VIII are there so much like coal-measure 

 slates that the villagers of St. Clair explore them for coal beds ; which of 

 course do not exist. They are near the base of the Devonian. 



At Weiset's house and southward the outcrop of the ore is at the bot- 

 tom, or on the east slope of Black Oak Ridge. See local section, Fig. 5. 



Figs. 5 and 6. Reduced to a scale of 200 yards to one inch. 



Fig. 5. 



JEoea/ ffcfior, atfPa/ferjfTiouse 



Fig. G. 

 JJLoeal fecti'on at Wet'set's /icust 



t-ajUcaiJ 



From Griffith's house eastward, the outcrop ore is on the summit of the 

 ridge, and the bed spreads broadly down its gently-sloping back. See 

 local section, Fig. 6. 



From Walter's house, northeastward, the outcrop slips down the north 

 or front slope of the hill, facing the mountain, the hill top being about 

 150 feet above the brook. 



The Limestone Ridge (capped with sandstone) runs round south of the 

 ore ridge, and is twice as high (300 feet). 



As the sections are drawn to scale (horizontal and vertical the same) 

 they explain themselves, and proceed to the description of the ore beds 

 themselves. 



II. The Fossil Ore Beds. — There are three ore beds in the red shale 

 of V. They lie so close together that they can be quarried together where 

 the dip is gentle, as at Walter's. But they lie so far apart that they can- 

 not always be mined by one gangway where the dip is vertical or very 

 steep. 



The most northern openings in this range are 150 yards south of 



