- stromatolite
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—stromatolitic /stroh mat'l it"ik/, adj./stroh mat"l uyt'/, n. Geol.a laminated calcareous fossil structure built by marine algae and having a rounded or columnar form.
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Layered deposit, mainly of limestone, formed by the growth of blue-green algae (see cyanobacteria).These structures are usually characterized by thin, alternating light and dark layers that may be flat, hummocky, or dome-shaped. Stromatolites were common in Precambrian time (more than 543 million years ago). Some of the first forms of life on Earth are recorded in stromatolites in rocks 3.5 billion years old. Stromatolites continue to form in certain areas today, most abundantly in Shark Bay in western Australia.* * *
▪ geologylayered deposit, mainly of limestone, formed by the growth of blue-green algae (primitive one-celled organisms). These structures are usually characterized by thin, alternating light and dark layers that may be flat, hummocky, or dome-shaped. The alternating layers are largely produced by the trapping of sediment washed up during storms on some occasions and by limestone precipitation by the blue-green algae on others.Stromatolites were common in Precambrian time (i.e., more than 542 million years ago). Some of the first forms of life on Earth are recorded in stromatolites present in rocks 3.5 billion years old. Although stromatolites continue to form in certain areas of the world today, they grow in greatest abundance in Shark Bay in western Australia. A matlike layer of blue-green algae is able to grow on the surface of sediments in the shallow waters there because evaporation causes high concentrations of salt that discourage snails and other organisms from eating the blue-green algae.* * *
Universalium. 2010.
