The micaceous soapstone rocks on both sides of the trail are covered with petroglyphs, from which the gap takes its name.
In the eastern portion of Princeton the underlying rock is a kind of micaceous schist, and in the western is granitic gneiss.
The pepitas occur in different forms, often adhering to micaceous specular iron.
(j) A simple recumbent slab of micaceous sandstone called the "Altar Stone."
Red Hall is the room next in order, and has on either side a red bank of sandy, micaceous clay.
