reworked material from the Merced formation
- fine grained sand
- silty sand
- occasional beds of clay as much as 2.5 m tick
2. Lower Aquifer: Merced
- Shallow marine and estuarine sediments with thin interbedded muds and peats
- Fine-grained layers (clays and silt)
Outcrops:
- coastal bluffs
- highlands west of San Bruno
- as far south as Hillsdale Blvd., San Mateo
