Published:January 01, 1984
“Bioerosion”, a term coined by Conrad Neumann in 1966 as an abbreviation of “biologic erosion”, encompasses the processes of wasting of indurated rock by organisms. The term has been used to describe every form of biologic penetration into hard substrates (i.e., lithic, skeletal or woody) together with destruction of the substrate and creation of preservable trace fossils that arise from the process. An extremely wide array of organisms are and have been involved in bioerosion (e.g., see Bromley, 1970; Warme, 1970, 1975), and their work has progressed at all scales from the microscopic to the gigantic. The minute scar etched on a shell by a brachiopod's pedicle has great paleoecologic significance. On the other hand, the sapping of cliffs by innumerable bivalves and sponges brings about the isolation of islands from continents; according to natural historians in Britain, the boring bivalve Zirfaea crispata is said to have played a leading role in the separation of England from the European continent! Had the Great Armada sent against England by Philip II of Spain in 1588 not been annihilated by the activities of the shipworm (a wood-boring bivalve), with the help of the unbored English fleet, the language of this textbook probably would have been Spanish!
The product of bioerosion that usually concerns geologists most is the development of a characteristic sculpture of the substrate, producing a bioerosion fabric, which is more or less equivalent to bioturbation fabric of unlithified sediments. Within a bioerosion fabric the individual structures produced by a bioeroding
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Ichnology: The Use of Trace Fossils in Sedimentology and Stratigraphy
Ichnology is a fascinating field of endeavor. As with science in general, it is a process of solving mysteries–in this case, mysteries of fossil behavior. In a very real sense the ichnologist is Sam Spade or Sherlock Holmes–following footprints, searching for traces of dastardly deeds, studying artifacts, attempting to reconstruct a sequence of events from subtle clues, pursuing the identity of someone (or something) long dead. Who was the culprit? What was he/she doing? Where was he/she living, working or going? Not only intellectually intriguing, ichnology also has practical application and economic importance. In today’s frenzied quest for energy and mineral resources, exploration geologists value every tool that aids their search. Ichnologic observations and analyses can help the sedimentologist reconstruct ancient depositional environments, help the stratigrapher correlate sedimentary strata, help the paleontologist determine the nature of fossil communities, and help the geochemist determine the effect of organisms on sediment composition. This publication was written to serve as a comprehensive and intelligible introduction to ichnology for anyone with even rudimentary geologic training, whether or not that person enrolls in a formal course on the subject. The book emphasizes sedimentologic, stratigraphic and paleoecologic al aspects of ichnology.