Geomorphic Features Shaped by Crossing Waves

Ridge-like shoal topography is well developed on the continental shelves of the Mid-Atlantic Bight and the northeastern Gulf of Mexico. In both cases, these linear sand ridges are oriented parallel to the predominant wave approach direction, suggesting common processes for their evolution and maintenance. Along the coasts of tropical islands surrounded by coral reefs, spur-like features are sometimes found. The spurs consist of coral rubble made available by the die-off or destruction of coral through natural processes or anthropogenic factors. The spur features emanate from rubble fields and are aligned parallel to the predominant direction of wave attack. These features, from disparate environmental settings, owe their maintenance and evolution to crossing wave patterns that form through refraction of waves up either side of the shoal or spur features. This paper presents examples of these geomorphic forms in both settings. Existing capabilities for simulating crossing wave processes are discussed.