Geology
These peaks along with Blue Knob form a grouping of mountains that stand out as a massif from the rest of the Allegheny Front and form some of the highest elevations in Pennsylvania's Allegheny Mountains. Blue Knob is separate from the rest of the Allegheny Front escarpment, and the mountain's lower base is made up of siltstone and shale of the Devonian Catskill and Devonian-Mississippian Rockwell formations. The upper slopes and summit are made up of the buff-colored Mississippian Burgoon Formation of sandstone and conglomerate, which is far more resistant to weathering than the underlying shale and siltstone. The rocks near the summit have a bluish-green appearance, giving Blue Knob its name.
Read more about this topic: Blue Knob (Pennsylvania)