stromatolite, layered structures produced by the binding together of sediments by a thin layer of cyanobacteria. 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.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2024, Columbia University Press. All rights reserved.
See more Encyclopedia articles on: Geology and Oceanography
