David Scott Felton

Master of Science

December 12, 1991

(B. S., Furman University, 1986)

Directed by Robert A. Gastaldo

Crevasse splays, although previously investigated in a variety of depositional environments, remain relatively poorly understood. An active crevasse splay developing within the southern portion of the Mobile-Tensaw River Delta offered an opportunity to investigate crevasse- splay formation and development. The splay was investigated through surface observations and by vibracoring and box coring to obtain subsurface data. Following field study, the cores were brought to the laboratory where they were processed in order to obtain detailed information as to grain-size trends, sedimentary and biogenic structures, and carbon content.

Analysis of the resulting data indicated that the crevasse splay is composed of several subenvironments. These subenvironments are the main crevasse channel, abandoned channels, distributary mouth bars, the crevasse shield, natural levees and an interdistributary bay (Chacaloochee Bay). The sediments recovered through coring were grouped into four facies: Sand, Mixed Sand, Mud, and Organic. Each of the crevasse-splay subenvironments exhibited a distinctive suite of sedimentary facies. This allowed for subsurface correlation and the development of a model explaining crevasse-splay formation and development.

This study showed that crevasse splays of the Mobile-Tensaw River Delta are important elements of estuarine bayfill. As a result, they play an important role in the continued development of the Mobile-Tensaw River Delta. Crevasse splays are complex and dynamic systems. Local flora, clastic sediment, wind, tides, floods, and the geometry of the region all play a major role in the development of these systems. Study of this modern crevasse splay indicated that crevasse-splay deposits of the Mobile-Tensaw River Delta probably do not offer much potential for economic development except under very specific and unusual conditions.

See Slone and Webster for related M.Sc. Theses.