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Figure 4. Time-thickness diagram for the northwest San Joaquin Basin margin. Individual bars represent ~40 m stratigraphic intervals correlating to faunazonules 6 and 7 of Adegoke (1969) in the Santa Margarita Formation and ~200 m stratigraphic intervals correlating to faunazonules 8-16 of Adegoke (1969) in the Etchegoin Group. Rapid subsidence in the basin coincident with Coast Range uplift in the earliest Pliocene slowed substantially by the middle Pliocene. Late Pliocene basinal subsidence was less than one-third that of the Early Pliocene. Closing of the Priest Valley Strait (Figure 6) in the latest Pliocene coincided with a slight increase in basin subsidence prior to filling with lacustrine and fluvial sediments of the Tulare Formation.