Figure 110. (A-C) Plan views of the Sand Key shelf-margin and outlier reefs traced from the aerial photo (Fig. 106B) show how irregularities along the margin edge could develop as backreef troughs become filled with sediment. (D, E) Generalized plan view of hypothetical composite-margin section is drawn from present morphologies at Alligator and Tennessee Reefs (Figs. 49A, 67), and Maryland and Pelican Shoals (Figs. 87B, 89, lines 4 and 3). Shelf-edge promontories could develop as infilling of troughs behind single outlier reefs extends parts of the margin seaward. Promontories on either side of an existing reentrant would enlarge the reentrant. A new reentrant could form where outlier reefs are lacking, as off Pelican Shoal. These models relate only to changing submarine morphology as sediment fills present accommodation space. Corals may or may not grow depending on many factors, including fluctuation of sea level.