Saona Island in the Eastern National Park, Dominican Republic

Saona Island in the Eastern National Park, Dominican Republic

The coast is the transitional band between the ocean and land which, by its geomorphic definition, forms the physical border of the land and the sea, based on its natural and physical components. These components are natural resources such as coastal vegetation, wetlands (mangroves), lagoons, salt flats, underwater prairies of grasses and algae (brown, green and red) and sand deposits, among others, that determine the geography of the resources located immediately along the water line. Coastal areas are bordered by the line of water and the distance inland in which salt flats, coastal vegetation or other coastal components are observed. The underwater coast is bordered by the line of water and the edge of the underwater island platform. The island platform is defined as the shelf which varies in size and depth that surrounds the islands. In the Caribbean, the islands that make up the Greater and Lesser Antilles have island platforms of various sizes and depths that extend to the drop offs to the deep ocean. The ocean bottoms in the platforms may be rocky or sedimentary, mostly consisting of calcium carbonate.

There are four kinds of coasts on the Caribbean islands. They are: beach, mangrove, rocky and alluvial plain. These kinds of coasts can be found on all of the islands of the Caribbean and may be present in a small length of coastline, a geomorphic characteristic singular to these islands.

A beach coast is one that contains deposits of unconsolidated sediments (gravel and sand) that extend from the base of a dune or vegetation to a depth where there is no movement of sediment. The sediments that make up the beach can be biogenic, terrigenous or mixed, depending on the predominant physical and geographic processes in the area. The composition and amount of these sediments depend on their topographic distribution due to watershed divisions. In Puerto Rico, Cuba, the Dominican Republic, Jamaica and other islands, biogenic beaches can be found in coastal zones where no permanent rivers flow and in areas with wide island platforms where mainly coral reefs, undersea prairies and algae are observed. Terrigenous and mixed beaches are found in coastal zones influenced by rivers or areas with high levels of runoff.

The mangrove is another kind of coast found in the Caribbean. It consists of a coastline with vegetation that has adapted to be able to colonize wetlands with salt intrusion. There are four main species of mangroves in the Caribbean. They are, in order of succession from the coast line to dry land: Rizhopora mangle (red mangrove), Avicennia germinans (black mangrove), Laguncularia racemosa (white mangrove) and Conocarpus erectus (button or buttonwood mangrove). The mangrove stands play various important roles in protecting the coastline, such as buffering ocean storms and as habitat for a variety of species.

The rocky coast consists of formations of igneous, sedimentary and metamorphic rock formations. Their location is determined by their geologic history. Rocky sedimentary coasts are one of the most interesting coastal components in the Caribbean because they form diverse geomorphic formations of great beauty and ecological importance, such as eolianites, the rocks formed on beaches and ocean terraces.

The alluvial plain is a kind of coast that is characterized by unconsolidated sediments of lime and clay. This kind of coast is found near river systems and alluvial deltas that have the capacity to carry sediment to the plain.

The Caribbean has a huge wealth of physical and ecological environments because of the variety and kinds of coasts and the physical and geomorphic components present in its small area. This makes the islands’ coasts a great attraction because of their high ecological and economic value.

Author: Maritza Barreto
Published: December 27, 2011.

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