Fourteen lignite outcrops from the Wilcox (lower Eocene) Group in Winston and Choctaw Counties in east-central Mississippi were studied by proximate and petrographic measurements. An inverse relationship was found between the ash content and seam thickness; in 12 of 14 seams investigated, the ash content decreased as the seam thickness increased. Increased ash content is apparently related to the type of lignite-forming environment (freshwater) and the proximity of nearby fluvial systems.

Lignitized tree trunk remains found in several seams were identified as belonging to the taxodiaceous (cypress) groups. In addition, a small amount of dicotyledonous woody material was found. This further points to an "upland" freshwater fluvial swamp environment.

Comparison of the cellular humic material (textinite and ulminite) versus the macerated humic material (humodetrinite) may indicate the physical and botanical environment present during the period of humic accumulation. The data identify two types of plant communities and corresponding physical environments that might enhance humic accumulation from a particular plant community. The two types of marsh or swamp plant communities, based on maceral identifications, are: (1) cellulose-rich/lignin-poor plants (reeds and angiosperms) associated with macerated humic material (humodetrinite), and (2) cellulose-poor/ligninrich plants (Taxodium) associated with cellular humic material (textinite and ulminite).

Eight of 11 seams petrographically investigated contain a preponderance of humodetrinite (cellulose-rich/lignin-poor) material, implying that most of the lignite seams were formed from a reed-dominated plant community.

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