

6. JACKSON TOWNSHIP. F\ 231 



southeast dipping side of the West Tuscarora anticline. At 

 the east end of Horse valley both sides meet, the small in- 

 tervening fold disappears, and the united mountains become 

 the anticline of Conecocheague in Madison township. No 

 gap exists along its whole course. 



4. Bower mountain. This lofty range passes completely 

 across the township as an undivided anticline with an aver- 

 age height of about 2000 feet above the sea. This range is 

 untra versed by any gap or even low place in the township. 



5. A short spur, caused by an anticlinal fold projects from 

 the Blue mountain near the west side of the township into 

 Henry valley, partly dividing it. The southern of the two 

 portions rapidly rises and comes to an end on the top of the 

 Blue mountain, and the synclinal knob thus formed is the 

 southern wall of a deep valley or ravine called Three Square 

 Hollow, in Cumberland county. 



6. The Blue mountain forming the southern line of the 

 township and county consist as elsewhere of a monoclinal 

 south dipping range, the other side of which has been com- 

 pletely removed by erosion. 



The Clinton group. {No. V.) 



The outcrop of the Clinton running along the south slope 

 of Conecocheague mountain is much obscured by wreckage 

 from the crest of the mountain and difficult of access, the 

 ground being covered with timber. 



The rocks of this group are, however, well exposed where 

 they are brought up by the axis of Chestnut ridge. This 

 ridge which first becomes conspicuous at Waggoner's mill, 

 near Centre, in Tyrone township, is apparently the continu- 

 ation of the main axis of the vale of Bloomfield, and conse 

 quently of Half Falls mountain, an axis which comes in 

 from the east side of the Susquehanna and traverses the 

 whole of Perry county. It elevates the Onondaga gray shale 

 at the east end of Centre township, the variegated shale 

 almost immediately afterward and as it approaches Loys- 

 villn the red shale appears at the surface for the first time. 

 Continuing westward it brings up the ore sandrock and 

 green T)assage shale at Waggoner s mill on the edge of 



