This is a special area where the rock base of the land is called diabase (sometimes called Dolorite or Black Granite). The rocks are know by the term “Ringing Rocks” because they ring when struck. This area near us has boulders piled up one on top of the other and not much grows there – hasn’t for thousands of years.
To quote the “UNAMI CREEK VALLEYS LANDSCAPE CONSERVATION PLAN”
“The Unami Creek Valleys landscape system is approximately 10,000 acres (15.8 square mile) of mostly unprotected contiguous woodlands that includes the majority of the lower Unami Creek and Ridge Valley Creek watersheds east of the Northeast Extension of the Pennsylvania Turnpike and several contiguous forest areas. The Unami Creek Valleys stands as one of the largest remaining forested landscapes in southeastern Pennsylvania, supporting a vast, interconnected mosaic of relatively natural habitat, with at least 30 patches of forest-interior habitat (30 acres or greater), a series of uncommon diabase woodlands, and over 24 miles of perennial streams, most of which are well buffered by forest. The area is distinguished from the gently rolling red shale landscape by its unusually broad forest cover, prominent, diabase ridges and sharply defined valleys. The ecological integrity inherent in this landscape has resulted in an extraordinary combination of unique forest and meadow plant communities, forest-nesting bird species, and high quality streams.”