The Allegheny Formation makes up the base of the three local formations. It can be found along the Kiskiminetas River. The two defining characteristics of the formation are the Upper Freeport sandstone and shale, and the Upper Freeport coal bed. Mining of the Upper Freeport Coal is one of the reasons for mine subsidence locally. It is one of the largest coal seams locally.
Examples of Upper Freeport Sandstone along PA 66, a half mile from Parks Township.
Formations Above the Allegheny Formation
More about the Allegheny Formation Online
- Formation Page – United States Geological Survey
- Stratigraphic section, Middle Pennslyanian Allegheny Formation – Research Gate
- Virtual Guide to Southwestern Pennsylvania Stratigraphy – The RockDoctor