OOIDSOne of my favorite sedimentary rock features, ooids. These are small, rounded grains of calcium
OOIDSOne of my favorite sedimentary rock features, ooids. These are small, rounded grains of calcium carbonate, usually 1-2 millimeters in diameter.Ooids are like coated sand grains. They form in areas where carbonate minerals are readily precipitating, such as warm, tropical oceanic waters. They need a core to start off growth, usually a sand sized grain of sediment or shell fragment. As those grains are tossed around by the waves, typically in a beach or near shore setting, newly formed carbonate minerals grow around the edges. The action of the waves rolls the grains, mostly keeping them from sticking together and allowing them to grow on all sides, forming these nice little spheres.You’ll sometimes find entire rocks made of these known as oolitic limestones, and in fact there’s even a small town named Oolitic in Indiana (although residents always told me they pronounced the word different, with a long O sound in the name of the town).-JBBImage credit: https://flic.kr/p/8EsGdGRead more:http://www.sandatlas.org/2012/09/oolite/http://blogs.agu.org/georneys/2011/09/11/geology-word-of-the-week-o-is-for-ooid/http://www.sepmstrata.org/page.aspx?pageid=105http://en.wikipedia.org/wiki/Oolitic,_Indiana -- source link
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