[4] The Vasquez Formation unconformably overlies Triassic basement of the Mount Lowe intrusive series, and localized the Jurassic syenite occurring in the area.

[7] In the Soledad Basin and the San Andreas Fault Zone, the formation is described by the United States Geological Survey (USGS) as: Early Miocene to Oligocene?

yellowish and reddish sandstone, conglomerate, and interbedded andesite-basalt, lying on pre-Tertiary crystalline basement rocks and unconformably below strata of Tick Canyon Formation; total thickness as much as 3,810 metres (12,500 ft).

The lenses of granitoid crackle and jigsaw breccia in the Vasquez Formation north of Blue Ridge were concluded to be rock-avalanche deposits.

[10] Zircons found in the overlying Tick Canyon strata and interpreted as coming from the Vasquez volcanics were dated at 25.3 ± 0.1 Ma.

[12][13][14] In the Early Miocene, around 21 Ma, the paleogeography of the area has been interpreted as an existing high to the southeast of the Soledad Basin, where the alluvial fans prograded towards the northwest.