ABSTRACT
River systems that carry large suspended loads and discharge into marine basins distinguished by low marine energy conditions generally build broad, clay-rich subaqueous platforms over which coarser grained subaerial and shallow-marine deposits prograde. Low-angle subaqueous slopes that typify the deltas are commonly characterized by processes and resulting geomorphic response features that indicate the disruption of “normal” sedimentary patterns and the displacement of sediments to deeper areas of the shelf and slope. The steepest regional slopes of the modern subaqueous Mississippi River delta are associated with the bars that form adjacent to the main distributary mouths. As is characteristic of sediments in the interdistributary bays, a high sedimentary gas content is present in the rapidly deposited clays of the delta-front environments. Downslope from the major mud nose scarp a thin blanket of acoustically amorphous sediment is commonly present. Sediments in the toe lobes of deformational systems such as delta-front gullies have been transported, remolded, and redeposited.
