Jasper Point Formation
Jasper Point Formation
Triassic and Permian(?)
Consists of massive, pillowed, and brecciated basalt overlain by 100 m of red, white, brown, and black, rhythmically layered radiolarian chert, both altered to prehnite or chlorite grade. Top of chert interbedded with and gradationally underlies the Penon Blanco Volcanics. Locally intensely deformed into a structural mélange. Structurally overlies the Tuolumne ophiolite-mélange (unit CPTO). Units CPTO and CPJP may be upper and lower part of the same ophiolite. This unit does not have recognized fossils nor radiometric ages. The age is constrained by the overlying and underlying units. As such, it may be as old as Permian, which differs from the formally accepted age of Triassic.