User:Salll327/sandbox

Biostratigraphy edits made to live page so far:


 * Fixed grammatical error (Characterised -> characterized [in 2 places]) in Concept of Zone Paragraph. (*Is this page supposed to be written in British English?)
 * Changed grammar to correlate with rest of article (Favoured -> favor in third paragraph and Recognised -> Recognized in second paragraph
 * Fixed grammatical error (Rccognise -> Recognized) in third paragraph.
 * Added citation for 2 types of biozone; Taxon range and Concurrent range from the following URL: http://quaternary.stratigraphy.org/stratigraphic-guide/biostratigraphy
 * Changed Grammar in Zone paragraph - British to American English to keep consistent with rest of article - metres to meters

Biostratigraphy edits made for sandbox (to go live in the future):


 * Biostratigraphy Definition - Edited flow and added 2 sentences to the end trying to wrap up the concept explanation.  - Citation Added: "Hine, Robert. “Biostratigraphy.” Oxford Reference: Dictionary of Biology, 8th ed., Oxford University Press, 2019."
 * Biostratigraphy History - Citation Added: "Gon, S. M. “Trilobite Biostratigraphy.” Edited by Nicolas Tormo, Trilobite Biostratigraphy, 4 Sept. 2018, www.trilobites.info/biostratigraphy.htm."
 * Biostratigraphy Zone Paragraph - Removed bullet-ed list and created/separated two paragraphs
 * Added sentence at the end of the paragraph, integrating index fossil bullets from "index fossil' section.
 * Added/rearranged paragraph for faunal succession.
 * Added Citation: "Scott, Michon (May 8th, 2008). "William Smith: Discovering Faunal Succession & Faunal Succession's Legacy". Earth Observatory."
 * Added hyperlink to other wikipedia pages.

Pre-Change

Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them. Usually the aim is correlation, demonstrating that a particular horizon in one geological section represents the same period of time as another horizon at some other section. The fossils are useful because sediments of the same age can look completely different because of local variations in the sedimentary environment. For example, one section might have been made up of clays and marls while another has more chalky limestones, but if the fossil species recorded are similar, the two sediments are likely to have been laid down at the same time.

Post-Change

Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them. The primary objective of birostratigraphy is correlation, demonstrating that a particular horizon in one geological section represents the same period of time as another horizon at a different section. Fossils within these strata are useful because sediments of the same age can look completely different, due to local variations in the sedimentary environment. For example, one section might have been made up of clays and marls, while another has more chalky limestones. However, if the fossil species recorded are similar, the two sediments are likely to have been laid down around the same time. Ideally these fossil are used to help identify biozones, as they make up the basic biostratigraphy units, and define geological time periods based upon the fossil species found within each section.


 * Edited flow and added 2 sentences to the end trying to wrap up the concept explanation.
 * Citation Added: "Hine, Robert. “Biostratigraphy.” Oxford Reference: Dictionary of Biology, 8th ed., Oxford University Press, 2019."
 * Added hyperlinks to other wiki pages.

Pre-Change

Biostratigraphy originated in the early 19th century, where geologists recognized that the correlation of fossil assemblages between rocks of similar type but different age decreased as the difference in age increased. The method was well-established before Charles Darwin explained the mechanism behind it—evolution.

Post-Change

Basic concepts of biostratigraphic principles were introduced well over centuries ago. A Danish scientist and bishop by the name of Nicolas Steno was one of the first geologists to recognize the rock layers correlate to the Law of Superposition. With advancements in science and technology, by the 18th century it began to be accepted that fossils were remains left by species that had become deceased and were then buried within the rock record. Here, scientists William Smith, George Cuvier, and Alexandre Brongniart came to the conclusion that fossils then indicated a series of chronological events, establishing layers of rock strata as some type of unit, later termed biozone. From here on, scientists began relating the changes in strata and biozones to different geological eras, establishing boundaries and time periods within major faunal changes. By the late 18th century the Cambrian and Carboniferous periods were internationally recognized due to these findings. During the early 20th century, advancements in technology gave scientists the ability to study radioactive decay. Using this methodology, scientists were able to establish geological time, the boundaries of the different eras (Paleozoic, Mesozoic, Cenozoic), as well as Periods (Cambrian, Ordovician, Silurian) through the isotopes found within fossils via radioactive decay.


 * Citation Added: "Gon, S. M. “Trilobite Biostratigraphy.” Edited by Nicolas Tormo, Trilobite Biostratigraphy, 4 Sept. 2018, www.trilobites.info/biostratigraphy.htm."
 * Added hyperlinks to other wikipages.

Pre-change: = Paragraph Exists

Post-Change = Paragraph Moved Below

Ammonites Paragraph will replace index fossil section and be expanded upon. Pre-Change

Ammonites, graptolites, archeocyathids, and trilobites are index fossils that are widely used in biostratigraphy. Microfossils such as acritarchs, chitinozoans, conodonts, dinoflagellate cysts, ostracods, pollen, spores and foraminiferans are also frequently used. Different fossils work well for sediments of different ages; trilobites, for example, are particularly useful for sediments of Cambrian age. To work well, the fossils used must be widespread geographically, so that they can occur in many different places. They must also be short lived as a species, so that the period of time during which they could be incorporated in the sediment is relatively narrow. The longer lived the species, the poorer the stratigraphic precision, so fossils that evolve rapidly, such as ammonites, are favored over forms that evolve much more slowly, like nautiloids. Often biostratigraphic correlations are based on a fauna, not an individual species, as this allows greater precision. Furthermore, if only one species is present in a sample, it can mean that (1) the strata were formed in the known fossil range of that organism; (2) that the fossil range of the organism was incompletely known, and the strata extend the known fossil range. For instance, the presence of the trace fossil Treptichnus pedum was used to define the base of the Cambrian period, but it has since been found in older strata. If the fossil is easy to preserve and easy to identify, more precise time estimating of the stratigraphic layers is possible.

Post-Change


 * Added sentence at the end of the paragraph, integrating index fossil bullets from "index fossil' section.

Pre-Change

The zone is the fundamental biostratigraphic unit. Its thickness range from a few to hundreds of meters, and its extant range from local to worldwide. Biostratigraphic units are divided into six principal kinds of biozones:


 * Taxon range biozones represent the known stratigraphic and geographic range of occurrence of a single taxon.
 * Concurrent range biozone include the concurrent, coincident, or overlapping part of the range of two specified taxa.
 * Interval biozone include the strata between two specific biostratigraphic surfaces. It can be based on lowest or highest occurrences.
 * Lineage biozone are strata containing species representing a specific segment of an evolutionary lineage.
 * Assemblage biozones are strata that contain a unique association of three or more taxa.
 * Abundance biozones are strata in which the abundance of a particular taxon or group of taxa is significantly greater than in the adjacent part of the section.

Post-Change

Biostratigraphy uses zones for the most fundamental unit of measurement. The thickness and range of these zones can be a few meters, up to hundreds of meters. They can also range from local to worldwide, as the extent of which they can be horizontally partially relies on tectonic activity. Metamorphic folding and subduction, for example, are a two of the tectonic processes that run the risk of changing these zones' ranges. Biostratigraphic units are divided into six principal kids of biozones: Taxon range biozone, Concurrent range biozone, Interval biozone, Lineage biozone, Assemblage biozone, and Abundance biozone.

The Taxon range biozone represents the known stratigraphic and geographic range of occurrence of a single taxon. Concurrent range biozone includes the concurrent, coincident, or overlapping part of the range of two specified taxa. Interval biozones include the strata between two specific biostratigraphic surfaces and can be based on lowest or highest occurrences. Lineage biozones are strata containing species representing a specific segment of an evolutionary lineage. Assemblage biozones are strata that contain a unique association of three or more taxa within it. Abundance biozones are strata in which the abundance of a particular taxon or group of taxa is significantly greater than in the adjacent part of the section.


 * Removed bullet-ed list and created/separated two paragraphs
 * Added hyperlinks to other wikipages.

Index Fossil Section To be removed and added post Biostratigraphy history

Pre-Change

Ammonites, graptolites, archeocyathids, and trilobites are index fossils that are widely used in biostratigraphy. Microfossils such as acritarchs, chitinozoans, conodonts, dinoflagellate cysts, ostracods, pollen, spores and foraminiferans are also frequently used. Different fossils work well for sediments of different ages; trilobites, for example, are particularly useful for sediments of Cambrian age. To work well, the fossils used must be widespread geographically, so that they can occur in many different places. They must also be short lived as a species, so that the period of time during which they could be incorporated in the sediment is relatively narrow. The longer lived the species, the poorer the stratigraphic precision, so fossils that evolve rapidly, such as ammonites, are favored over forms that evolve much more slowly, like nautiloids. Often biostratigraphic correlations are based on a fauna, not an individual species, as this allows greater precision. Further, if only one species is present in a sample, it can mean that (1) the strata were formed in the known fossil range of that organism; (2) that the fossil range of the organism was incompletely known, and the strata extend the known fossil range. For instance, the presence of the trace fossil Treptichnus pedum was used to define the base of the Cambrian period, but it has since been found in older strata.

Post-Change

* Expand on the Bulleted List

To be useful in stratigraphic correlation index fossils should be:


 * Independent of their environment
 * Geographically widespread (provincialism/isolation of species should be avoided as much as possible)
 * Rapidly evolving


 * Easy to preserve (Easier in low-energy, non-oxidized environment)
 * Easy to identify

To work well, the fossils used must be widespread geographically, so that they can occur in many different places. They must also be short lived as a species, so that the period of time during which they could be incorporated in the sediment is relatively narrow. The longer lived the species, the poorer the stratigraphic precision, so fossils that evolve rapidly, such as ammonites, are favored over forms that evolve much more slowly, like nautiloids. Often biostratigraphic correlations are based on a fauna, not an individual species, as this allows greater precision. Further, if only one species is present in a sample, it can mean that (1) the strata were formed in the known fossil range of that organism; (2) that the fossil range of the organism was incompletely known, and the strata extend the known fossil range. For instance, the presence of the trace fossil Treptichnus pedum was used to define the base of the Cambrian period, but it has since been found in older strata. Pre-Change

Faunal succession[ edit]
Fossil organisms succeed one another in a definite and determinable order and therefore any time period can be recognized by its fossil content.

Post-Change

The concept of faunal succession was theorized at the beginning of the 18th century by a scientist by William Smith. When William was studying rock strata he began to recognize that rock outcrops contained a unique collection of fossils. The idea that these distant rock outcrops contained similar fossils allowed for Smith to order rock formations throughout England. With Smith's work on these rock outcrops and mapping around England, he began to notice some beds of rock may contain mostly similar species, however there were also subtle differences within or between these fossil groups. This difference in assemblages that appeared identical at first, lead to the principle of faunal succession, where fossil organisms succeed one another in a definite and determinable order, and therefore any time period can be categorized by its fossil extent.


 * Added/rearranged paragraph for faunal succession.
 * Added Citation: "Scott, Michon (May 8th, 2008). "William Smith: Discovering Faunal Succession & Faunal Succession's Legacy". Earth Observatory."
 * Added hyperlink to other wikipedia pages.