Figure 14. Schematic dip sections illustrating the relationship of shelf margin collapse to retrogradation. (A) An initial episode of shelf margin progradation is followed by retrogradation and renewed progradation. During this time a condensed section is deposited above the previous shelf and shelf margin. (B) When the active shelf margin progrades to the previous shelf margin, steep slopes trigger collapse of the active shelf margin, which excavates headward along the weak condensed section. (C) Through time, the collapse cannibalizes the earlier shelf and shelf margin deposits and transports them down slope into deep water. Details of slump blocks and slope aprons are not shown.