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Index fossils are fossilized remains of organisms that serve as convenient reference points to geologists because they were very widely distributed during a very short period. This means that, if a geologist is trying to figure out how old a certain segment of rock is, the presence of an index fossil will give him a very good idea to a pretty high level of certainty.
Most index fossils are aquatic, especially mollusks. This is because (a) mollusks had shells, which are easily preserved, and (b) marine organisms generally fossilize easily because they often live on sand and so turn into sedimentary rock, which forms without volcanic activity (like igneous) or intense pressure (like metamorphic).
One good example of an index fossil is Paradoxides, a species of trilobite that was distributed in seas all over the world, but only for a very small amount of time during the Cambrian Period, about 540 million years ago.
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Describe how geologists use an index fossil and list the three characteristics of a good index fossil?
Geologists use index fossils to date the rock layers they are found in and to correlate similar rock layers in different locations. Three characteristics of a good index fossil are: widespread distribution, short duration in the geologic time scale, and easily recognizable features.
How the characteristics of an index fossil are useful to geologists?
It gives information to scientists about the past. It also provides a reference of time throught rock layers. It can identify and define geological periods of time.
Is it true that To be a useful index fossil a species must have been rare?
No, an index fossil does not have to have been rare to be useful. The key characteristic of an index fossil is that it is easily recognizable, widespread geographically, and existed for a relatively short period of time. This allows geologists to use it to help date the rock layers in which it is found.
What are index and what do geologists learn from them?
Index fossils are very important to geologists because they identify geological. The fossil snail is a particularly difficult animal to study.
Why are index useful to geologists?
they tell the absoute age of rcoks which they occur
Describe how geologists use an index fossil and list the three characteristics of a good index fossil?
Geologists use index fossils to date the rock layers they are found in and to correlate similar rock layers in different locations. Three characteristics of a good index fossil are: widespread distribution, short duration in the geologic time scale, and easily recognizable features.
How the characteristics of an index fossil are useful to geologists?
It gives information to scientists about the past. It also provides a reference of time throught rock layers. It can identify and define geological periods of time.
Is it true that To be a useful index fossil a species must have been rare?
No, an index fossil does not have to have been rare to be useful. The key characteristic of an index fossil is that it is easily recognizable, widespread geographically, and existed for a relatively short period of time. This allows geologists to use it to help date the rock layers in which it is found.
What is the fossil called that geologists use to determine rock ages?
Index Fossil
What are index and what do geologists learn from them?
Index fossils are very important to geologists because they identify geological. The fossil snail is a particularly difficult animal to study.
What characteristics must a fossil have to be useful as an index fossil?
An index fossil must be of a rapidly evolving organism that only existed for a specific period of time, is easily recognizable, is abundantly preserved, and was widespread geographically. Most index fossils are therefore of marine organisms.
Why are index useful to geologists?
they tell the absoute age of rcoks which they occur
To be useful as an index fossil fuel spices must have existed for how long?
To be useful as an index fossil fuel, spices must have existed for about 1000 years.
Which characteristics of a fossil would you make it useful as an index fossil in determining the relative age of widely separated rock layers?
C). a narrow time range and a wide geographic range
What must be true for a fossil organism to be useful as a index fossil?
The absolute age of the index fossil was determine by radioactive dating or another absolute method
Why are index fossils so important to geologists?
Index fossils are very important to geologists because they identify geological time periods. Index fossils are found within a specific layer of rock- So when one finds the age of the rock layer, that is also the age of the index fossil.
How are the characteristics of index fossils useful to geologists?
It gives information to scientists about the past. It also provides a reference of time throught rock layers. It can identify and define geological periods of time.
