Formation of the Archipelago Hot
Los Roques, Formation of the archipelago.
In order to understand how the archipelago was formed it must be analyzed in the first place its geology. Studies show that all keys have an igneous metamorphic rock base completely covered by Carbonatic rocks and silt with the exception of Gran Roque. There it can be observed a springing of igneous Metaphorphic rock in three small hills that have a maximum height of 130 meters. The base of igneous rock was originated by a tectonic process which produced the springing of a great block or platform of igneous tock from the bottom of the sea. This emerging platform rose from depths close to 1000 meters. Evidence of this vertical movement of the bottom is the existence of abrupt slopes around the archipelago which at less than 3 kilometers from the coast are over 1.000 meters deep. Rocks and Carbonatic sediment which cover the platform comes from corals, coralline algae, mollusks and other organism that have skeletons with external support formed by carbonate compounds (calcium carbonate). When the igneous rock platform reached depths between 0 and 45 meters, the sediments began to grow over it in a massive way, vertically as well as horizontally. One of the conditions which corals need to grow massively and form coral reefs is the presence of sun light. So only when the platform emerged from the bottom and placed itself between 1 and 40 to 50 meters from the surface, the reefs began to develop themselves. While the corals died by natural means or by exposure outside the water, the calcareous residue of their skeletons remained deposited. These began to degrade through different physical and chemical processes and gave way to the Carbonatic rocks and sediment which now make up the outer layers the archipelago keys. This process occurred during the ice age.
Almost all the keys of Los Roques have a similar structure where the presence of two contrasting areas is outstanding: the first one is arid, grey made up by rocks of dead coral and mollusks shells which turn from white to grey due to the sun light and the tide. This area is known as the storm terrace and it is located on the windward side or open sea. Generally it is quite close to a coral reef where all the rock material is dragged by the waves. On the other side protected from the wind (leeward) or towards the inside part of the archipelago, the keys show a colorful and soft landscape, with bays of still water and areas where the mangrove has developed (Isla Larga, Cayo Sal) or extensive beaches of white sands as in Cayo Carenero. This last area stretches all the way into the sea with a soft slope, generally covered by prairies of marine herbs which can go 10 to 12 meters in depth. The structure of the Caribbean coralline key is also present in many of the keys of Los Roques. The coral reefs protect form the surf and the currents the space there is between them and the keys. This gives rise to a special make up of sediments which allow a quick invasion by marine herbs, mainly Thalassia Testudinum which needs still waters and stable sediments. Along the coast these same conditions are suitable for the colonization of red mangrove that can keep its roots in the water and compact sediments and organic residue in order to gain land from the sea.