Table 4 Brief descriptions and interpretations of facies types within the overbank facies association (FA-2)

Facies 2A: Interbedded sandstone–mudstone

Laterally persistent, alternate thick to thin sandstone grading to red mudstone beds; sheet-like geometry; crude plane laminations in sandstone.

Alternate traction and suspension load deposition under relatively low-energy conditions (Reineck and Singh 1980); sheet-like geometry indicates an overbank setting (Leopold and Wolman 1957).

Facies 2B: Plane-laminated sandstone

Plane-laminated, fine- to medium-grained sandstone beds, few cm to more than 10 cm in thickness; planar bedding show parting lineation; well sorted, subrounded to rounded quartz with few plagioclase feldspar and lithic fragments; small current ripples on top surface of beds; bioturbation by Skolithos isp. Common.

Plane-laminated sandstone with parting lineations indicates supercritical upper flow regime (Paola et al. 1989), possible during peak flood time (Miall 1977); ripples near top of beds indicate subcritical flow in shallow channels (Paola et al. 1989).