Minor sedimentary structures were studied in cores and exposures in the deltaic and marginal deltaic plains of the Mississippi River. Selected active environments were sampled and the occurrence of sedimentary structures from each was recorded. Twenty-five individual structure types are illustrated and described with notations on processes responsible for their formation. Individual structures were found to occur in more than one environment, however, suites of structures were characteristic. Within the study area the following 12 depositional environments have been investigated: shelf, prodelta, delta front (distal bar, distributary mouth bar, distributary channel, and subaqueous Jevee), subaerial levee, marsh, swamp, interdistributary bay, mudflat, and fresh water lake. Within each environment, individual structures tell of one or several events, while the total assemblage of structures approximates many of the conditions active during deposition.