Regional surface and subsurface studies indicate that thick deltaic (Queen City Formation) and thin shelf (Reklaw and Weches Formations) sequences compose the stratigraphic interval between the top of the Carrizo Sand and the base of the Sparta Formation.

Three principal depositional systems were defined within the Sparta Formation of Texas using surface and subsurface data: high-constructive delta system in east Texas; strandplain-barrier bar system in central Texas; and high-destructive, wave-dominated delta system in south Texas.

Lignite occurs in three Eocene stratigraphic units--the Wilcox Group, Yegua Formation, and Jackson Group--and in three ancient depositional systems-fluvial, deltaic, and strandplain/lagoonal.

Structurally complex, heterogeneous, tide-dominated deltaic reservoirs in the Lower Misoa Formation (lower Eocene C members) in the LL-652 area of Lagunillas field in the Maracaibo Basin, Venezuela, have produced 166 million stock-tank barrels (MMSTB) of oil but have a low recovery efficiency of

Combining process and geomorphic description (supplied by studies of modern depositional systems) with the three-dimensional description of sedimentary units and their internal structures (accomplished in the stratigraphic record) produces an integrated facies model that can be applied to the int