Carbonate sand | Sand

34 images Created 27 Sep 2012

A hand full Sand
Holidays – dreaming of white beaches under tropical sunlight walking along the waterfront on soft, white sparkling beach sands that glide through our fingers when dry. They are composed of grains different in size and shape derived from shallow water areas nearby as there are coral reefs, seagras flats or submarine sand dunes where tidal currents and winddriven waves have washed the sands onto the beaches. Most of the sandgrains are the product of animals and plants living in the warm tropical seawater.
Particle types down to one millimeter in size can be visualized by eyes, a good magnifier ( 10x ) opens a fantastic insight into a world of organisms that are able to precipitate calcium carbonate in seawater forming skeletons, shells or fine branched framework. A first glance which provides an impression of an incredible variety of delicate white skeletons as there are small tests of foraminifera, a single-celled protozoan, sponge spicules derived from a fragile reticulate sponge network, or calcite elements of echinoderms with colorful spines or plates from sea urchins, brittlestars and crinoids. Molluscan shells of reef dwellers deliver a wide variety of carbonate particles as well. Major amounts of sand grains are derived from corals, the “white coral sand” whose particles are not produced by the living coral polyps rather than by the destruction of solid reef framework due to the activity of diverse boring, rasping and cracking organisms feeding on and in dead coral carbonate substrate.

Studying the variety of sand particles in a carbonate sand on the beach we learn more about the surrounding natural environments whether the biodiversity is still under stable conditions or suffering from natural or human impact. Finally we can imagine the importance of tropical marine environments as a trap to store carbondioxid from the atmosphere permanently in organic carbonate skeletons and later in earth history in carbonate rocks.
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