Nature leaves subtle evidence of antecedent conditions in the landforms and vegetation patterns that are present in the coastal areas. A significant challenge to coastal engineers is to attempt to interpret these clues in order to obtain a better understanding of the overall dynamics. An example is provided by the beach ridge patterns shown in Figure 9.1. The ridges in the center and left of the photograph are more or less shore parallel, as might be expected in the case of sand being transported shoreward and causing a shoreward advancement. However, the beach ridges to the right of the photograph are puzzling owing to their decidedly different orientation. Several questions are posed by this photograph. It is clear that at some time in the past the forces and sediment supply in the system were such that the beach was accreting. Is the beach still accreting and, if not, what were the causes that tipped the force balance to erosion? If erosion is presently occurring, will it continue or increase in the future? What were the forces that caused the different orientations of the beach ridges and, if they can be discerned, how can this information be applied to future shoreline trends? Usually, questions of this type cannot be answered without additional information. This problem can be likened to that of attempting to discern a picture with only a small number of pieces of a jigsaw puzzle.