Figure 2. Features of a typical retrograde failed shelf margin in which slump blocks are a small part of the fill. In this and some of the following figures, the profile of the previous shelf and shelf margin are used to project the approximate position of a filled collapse scar. The collapse discontinuity is primarily an unconformity in which high relief headwall truncates updip strata. Isolated slump blocks of updip strata rest on the collapse unconformity. Gravity flow sands locally rest on the collapse unconformity and slump blocks. The collapse scar is filled mostly with deepwater shales, and is finally capped by prograding shallow water deposits.