404 R. M. Field — Middle Ordovician of Central 



stones are separated by the Silurian sandstone of Nittany 

 Mountain into the areas roughly represented by Nittany 

 Valley to the west and Penns Valley to the east. The 

 large eastern terrane located in the rich and beautiful 

 canoe-shaped valley of the Kishacoquillas in Mifflin and 

 Huntingdon counties has an approximate area of 140 

 square miles. 



Fig. 1. 



LYCOMING 



Fig. 1. — Map of Central and South Central Pennsylvania. 

 The black areas show the distribution of the Ordovician formations in 

 the province. The numbers refer to the locations of the sections as fol- 

 lows: — 1. Coburn. 2. Millheim. 3. Spring Mills. 4. Salona. 5. Belle- 

 fonte. 6. Tyrone. 7. Franklinville. 8. Eoaring Spring. 9. Loysburg. 

 10. Thorpes Quarry-Willow Grove. 11. Lemont. 12. Center Hill. 13. 

 Reedsville. 14. Belleville. 15. Naginey. 16. Chambersburg. 



