![]() Top left – polarised light in air: ooid banding and the outer band appears dark central nucleus more obvious interior banding distinct with some indications of past signs of initial spalling. Micrographic techniques in the examination of Joulters Cay ooids at ×340 magnification. The tangential aragonite crystals show a pseudo-uniaxial cross under crossed-polars. Under the microscope, in thin section, the ooid is a thing of beauty. The ooid is formed chemically in warm agitated shallow water by bacteria and algae precipitating aragonite (a form of calcium carbonate). The nucleus is usually a foraminifer, algal particle, or a shell fragment. ![]() Great, you say, but what is an ooid? An ooid is a small (ranging from 0.25 to 1 mm in diameter), round, or oval, concretion, resembling fish roe, with many successive concentric layers about a central nucleus. The islands are also composed of cemented ooids (called oolite) forming sand ridges, about 3 m high and 50 m apart. The shoals here are a series of bars on a large shallow sand flat of about 400 km 2 in size. The ooid deposits are in large mobile shoals located between the Cays, or islands. ![]() Here the white sands are “ooids”, and the island is one of the three Bahamian Joulters Cays, off the northernmost tip of Andros Island. Well, on tropical islands, the sands are usually carbonate (limestone) sands composed of many different skeletal remains.īut on this particular island, things are different. Then, how about a visit to a warm tropical beach with palm trees swaying in a gentle soft breeze, pure white sands, and a gorgeous blue-green sea with gentle waves lapping the deserted shore? In England, is it raining? Is it pouring? Are you wet? Are you cold? Miserable? Home | Resources | Articles | Ooids on a tropical island beach Ooids on a tropical island beach By Hugh Mitchell-Tapping ![]() Bulletin of the Quekett Microscopical Club. ![]()
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