Environments in which peat is forming today are present throughout coastal Louisiana and include small coastal basins between distributary channels and broader inland flood basins separated by major Mississippi River courses. Coastwise marsh belts between beach ridges of the chenier plain contain a relatively thin surface mantle of peat. Information from more than a thousand shallow borings shows that peats accumulated in similar environments during the past several thousand years. These deposits can be differentiated and related to older deltas of the Mississippi River.

In delta sequences, peat occurs in the aggradational delta-plain facies, interfingers laterally with inorganic natural-levee deposits, and overlies pro-gradational sandy delta-front facies and basal prodelta silty clays. Repetitive sequences containing delta-plain peat occur in the subsurface. The thickest peat deposits accumulated in fresh-water inland swamps, which occupied broad flood basins, where environments were more stable. The stratigraphic relationships of delta-plain peats to enclosing facies and repetitive delta sequences are comparable to those in the Carboniferous Yoredale Series of northern England.