Seismic-reflection profiles and long-range side-scan (GLORIA) sonographs reveal the relative age relationships between the major distributary channels of the upper and middle Amazon deep-sea fan. These age relationships, in turn, suggest that the fan grows through formation of a succession of broad levee complexes, each of which consists of several individual leveed distributary channels whose levee systems overlap or coalesce with one another. Only one channel is apparently active at any given time on an actively growing levee complex. Eventually this channel is abandoned, probably through avulsion, and a new channel and associated levee system form nearby, thereby enlarging the levee complex. Occasionally, the formation of a new channel will cause the present levee complex to be abandoned and will initiate a new levee complex at a different location. In this manner, a succession of overlapping levee complexes is formed through time, and the fan grows upward as well as radially outward downslope.

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