Beach-Ridges: A Review
Keywords:Beach-ridges, cheniers, sea-level, coastal progradation
A review of the beach-ridge literature is provided with emphasis on those composed of sand. Although confusion in the literature exists on differentiating beach-ridges from cheniers, both are viewed here as morphogenetically distinct. Several models describing the evolution of beach-ridges in diverse coastal settings have been published. Review of these models indicates that beach-ridges are deposited by swash during high or low wave energy conditions, and may also emerge through aggradation of an offshore bar. Additionally, numerous models emphasize the role of vegetation and aeolian deposition in the stabilization, accretion, and preservation of beach-ridges.
Beach-ridges generally prograde when an abundance of sediment exists and the offshore gradient is low. Sea-level changes do not determine beach-ridge growth, but can affect the orientation and elevation of beach-ridge sets in a beach-ridge plain. Interruption, truncation, erosion of beach ridges, and deposition of younger beach-ridges with a different orientation and shape may be caused by climate, sea-level, or sediment supply fluctuations. Thus beach ridges are utilized in the reconstruction of sea-level, climate, and sediment budget histories.
Growth rates of beach-ridges are studied in an attempt to elucidate rates of coastal progradation. Absolute quantification of beach-ridge growth rates is limited by the scarcity of reliable in situ material for dating. Growth rates can also be erroneous due to erosion of some beach-ridges making up a beach-ridge plain. The study of beach-ridges has progressed from descriptions of their morphology and discussions on bench-ridge origin, to the use of these landforms in the interpretation of paleo-environments.