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Oncolitic limestones have oncolites - macroscopic, concentrically layered, ~irregularly spheroidal masses of variable size. The oncolites are biogenic in origin - they grew in successive layers by the active or passive precipitation of calcium carbonate by cyanobacterial films (oncolites can be considered as mobile varieties of stromatolites).
Uluru (Ayers Rock) is a large sandstone formation in Northern Territory, Australia.. Sedimentary rocks can be subdivided into four groups based on the processes responsible for their formation: clastic sedimentary rocks, biochemical (biogenic) sedimentary rocks, chemical sedimentary rocks, and a fourth category for "other" sedimentary rocks formed by impacts, volcanism, and other minor processes.
Sedimentary structures include all kinds of features in sediments and sedimentary rocks, formed at the time of deposition. Sediments and sedimentary rocks are characterized by bedding , which occurs when layers of sediment, with different particle sizes are deposited on top of each other. [ 1 ]
Siliceous ooze is a type of biogenic pelagic sediment located on the deep ocean floor. Siliceous oozes are the least common of the deep sea sediments, and make up approximately 15% of the ocean floor. [1] Oozes are defined as sediments which contain at least 30% skeletal remains of pelagic microorganisms. [2]
Primitive rocks are common on the surfaces of many asteroids, and the majority of meteorites are primitive rocks." [1]: 145 Widmanstätten pattern in an iron-rich meteorite. An example of a primitive rock is the achondritic iron-nickel octahedrite mineral seen in the Widmanstätten pattern that is found in a number of iron-rich meteorites.
This rock was part of the Roman aqueduct of Mons/Montauroux–Fréjus and was most probably derived from the karst area in the vicinity. In geology, lamination (from Latin lāmina 'thin layer') is a small-scale sequence of fine layers (pl.: laminae; sg.: lamina) that occurs in sedimentary rocks.
Art: marble, although a metamorphosed limestone, is an example of the use of sedimentary rocks in the pursuit of aesthetics and art Architectural uses: stone derived from sedimentary rocks is used for dimension stone and in architecture , notably slate (metamorphosed shale ) for roofing , sandstone for load-bearing buttresses
Some Archean rock formations show macroscopic similarity to modern microbial structures, leading to the inference that these structures represent evidence of ancient life, namely stromatolites. However, others regard these patterns as being the result of natural material deposition or some other abiogenic mechanism.