- Often divided into two terranes - Pickett Peak to the
east, and Yolla Bolly to the west divided physically by a
low angle, east dipping fault
- Composed of metaclastic rocks, metacherts, and
metagreenstone with smaller amounts of serpentintite
- Represent oldest rocks of the Franciscan - dated @ 80-160
Ma
- Highest grade of metamorphism
in Pickett Peak- still blueschist (high P, low T)
- Imbricate faulting dominate here, bounded on the east by
series of faults separating Franciscan from Great Valley
