| 词汇 | index-fossil |
| 释义 | index fossil noun[ C ] geology specializeduk /ˈɪn.deks ˌfɒs.əl/ us /ˈɪn.deks ˌfɑː.səl/ a fossil that is found in many places and comes from the same time in history, so that scientists can use it to decide how old certain rocks are标准化石 Palaeontology & fossils ammonite ammonoid biozone carbon dating fossil fossil record fossilization fossilize fossilized microfossil missing link palaeontologist palaeontology petrifaction petrify radiocarbon dating unfossiliferous index fossil | American Dictionaryindex fossil noun[ C ] us/ˈɪn·deks ˌfɑs·əl/ earth science a fossil that is found in many places and comes from the same time in history, so that scientists can use it to decide how old certain rocks are Examples of index fossilindex fossil Fauna and flora specific to a particular environment make poor index fossils, as environment, rather than temporal restriction, may be dictating their appearance and distribution. True index fossils should be temporally restricted, common and widespread. It has a cosmopolitan distribution and is an important indexfossil in biostratigraphy. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. It is used in biostratigraphy as an indexfossil. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. The series of deposits that spans the occurrence of a particular indexfossil, is often referred to as that fossil's zone, enabling to relate different faunas through time. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Firstly, index fossils should be temporally restricted, numerically abundant and spatially widespread. Apart from conodonts, goniatites are the best index fossils, which have considerably completed the biostratigraphic calibration of our sections. An absence of facies bias potentially increases the usefulness of these taxa as index fossils, but their global utility is restricted by their endemism (see above). Because certain fossils are solely found in certain layers, they are referred to as index fossils. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Such index fossils must be distinctive, be globally distributed and have a short time range to be useful. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Such index fossils must be distinctive, be globally distributed and occupy a short time range to be useful. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Misleading results are produced if the index fossils are incorrectly dated. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. They are excellent index fossils, and it is often possible to link the rock layer in which they are found to specific geological time periods. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Some flood geologists dispute geology's assembled global geologic column since index fossils are used to link geographically isolated strata to other strata across the map. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Fossils are often dated by their proximity to strata containing index fossils whose age has been determined by its location on the geologic column. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. See all examples of index fossil These examples are from corpora and from sources on the web. Any opinions in the examples do not represent the opinion of the Cambridge Dictionary editors or of Cambridge University Press or its licensors. |
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