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layered structures produced by the binding together of sediments by a thin layer of cyanobacteriacyanobacteria
or blue-green algae,
photosynthetic bacteria that contain chlorophyll. For many years they were classified in the plant kingdom along with algae, but discoveries made possible by the electron microscope and new biochemical techniques have shown them to be
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. The layers, which are deposited very slowly, gradually produce rounded or hummocklike formations. Stromatolite fossils are common in Precambrian rocks, and the cyanobacteria associated with them are believed to have been a major contribubutor to the increasing oxygen of the early earth. Stromatolites now are found primarily in environments where high salt levels discourage animals from eating the cyanobacteria.



a dense, layered structure that forms in limestones and dolomites as a result of the presence of colonies of blue-green and other algae. Stromatolites reach several meters in length and 1–2 m in height. They have been traced back to the Proterozoic; Upper Proterozoic and Lower Paleozoic fossils are particularly common. The formation of stromatolites occurs in warm, shallow waters with elevated or decreased salinity. The various morphological types, which evolved during the course of geological time, are used for the biostratigraphic analysis of Upper Proterozoic deposits, in which remains of other organisms are extremely rare.


A structure in calcareous rocks consisting of concentrically laminated masses of calcium carbonate and calcium-magnesium carbonate which are believed to be of calcareous algal origin; these structures are irregular to columnar and hemispheroidal in shape, and range from 1 millimeter to many meters in thickness. Also known as callenia.
References in periodicals archive ?
But even though the stromatolites can be found now in shallow, salty waters, new research is suggesting that they formed in a hot spring-type environment, like the kind you would find at Yellowstone National Park in Wyoming, that only later transformed into how we see it today.
Stromatolites, microstromatolites, laminations, associated with calcified clumps, sedimentary fill and organic material (biofabrics) are the main microfabrics observed.
Matthew described them as Archaeozoon acadiense, the first Precambrian stromatolite properly identified in the scientific literature (Matthew 1890; Hofmann 1974; Miller 2003).
Stromatolites ("layered rocks") are rocky structures made by photosynthetic cyanobacteria.
Furthermore, understanding the microbial diversity of the perennially ice covered lakes in the McMurdo Dry Valleys may provide a significant insight into the formation of these calcified mats that are analogous to ancient stromatolites in a cold and pristine ecosystem.
Our tour stopped to look at the stromatolites at Shark Bay.
The collection also includes minerals, semi-precious stones and fossils, the oldest items being the three to four billion-year-old stromatolites, which are single cell organisms and are in fact considered to be the Earth's oldest fossils.
The method used in the study consisted of replicating the algorithm proposed by Petrisor and Decho for the study of the orientation of cyanobacteria in marine stromatolites (Petrisor and Decho, 2006).
In 1994 I began working in Belize, Central America, and Quintana Roo, Mexico, and have taken eighteen trips to the region conducting research on stromatolites, Jute snails, and hurricane damage on coastal cayes.
Understanding the formation of microbialites will provide insight that may contribute to interpreting the early record of life preserved in other organo-sedimentary structures such as stromatolites (Grotzinger and Knoll 1999).
Furthermore, they have been averted, contrary to the neo-Darwinian assertion that competition is the primary organizing principle for the evolution of life, through cooperative communities of bacterial mats on lagoons or as communities on rocky substrates that were being transformed into structures called stromatolites (some of them the size of houses).