page_title: Sedimentary structures
section_title: Biological structures
hierarchical_section_title: Sedimentary structures / Biological structures
caption_attribution_description: English: Skolithos trace fossil. Scale bar is 10 mm.
context_page_description: Sedimentary structures include all kinds of features 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. These beds range from millimeters to centimeters thick and can even go to meters or multiple meters thick.
  Sedimentary structures such as cross bedding, graded bedding and ripple marks are utilized in stratigraphic studies to indicate original position of strata in geologically complex terrains and understand the depositional environment of the sediment.
context_section_description: A number of biologically-created sedimentary structures exist, called trace fossils.  Examples include burrows and various expressions of bioturbation.  Ichnofacies are groups of trace fossils that together help give information on the depositional environment.  In general, as deeper (into the sediment) burrows become more common, the shallower the water.  As (intricate) surface traces become more common, the water becomes deeper.
  Microbes may also interact with sediment to form Microbially Induced Sedimentary Structures.
caption: Skolithos trace fossil. Scale bar is 10 mm.
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