Index Fossil Characteristics Explained
Index fossils are distinctive fossils used to date rock layers. They possess specific characteristics that make them valuable for geological correlation.
The key features of an effective index fossil are:
- Wide Geographic Distribution: The organism must have lived over a large area so that rocks containing it can be found in many different locations.
- Limited Stratigraphic Range: The organism must have existed for a relatively short period in geologic time. This allows for precise dating of the rock layer where the fossil is found. A short existence means the fossil appears in only a few specific layers.
Fossils that meet these criteria allow geologists to determine the age of rocks and correlate rock formations across different regions.
Based on these defining characteristics:
- Option 1 is incorrect because index fossils need to cover wide areas, not be limited geographically.
- Option 2 is incorrect for the same reason regarding geographic distribution.
- Option 3 is incorrect because while wide geographic distribution is correct, a wide time range is undesirable; a limited time range is needed for precise dating.
- Option 4 correctly identifies both essential characteristics: wide geographic distribution and a limited stratigraphic range.
Similar Questions
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Gypsum has lower density than anhydrite.
Reason (R) : Hydrated minerals tend to expand many times the original volume of the anhydrous minerals.
In the light of the above statements, choose the most appropriate answer from the options given below :
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Drumlins show features opposite to those of Roches Moutonnees.
Reason (R) : The stoss side is steep and the lee side is roughened.
In the light of the above statements, choose the most appropriate answer from the options given below :
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : In a hand specimen quartz can be easily distinguished from orthoclase.
Reason (R) : Orthoclase has lower refractive index than quartz.
In the light of the above statements, choose the most appropriate answer from the options given below :
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Chronostratigraphy is concerned with the mutual time relationship of strata.
Reason (R) : Formation, member and bed are units of chronostratigraphy.
In the light of the above statements, choose the most appropriate answer from the options given below :
Match List - I with List - II.
List - I
Mineral PropertyList - II
Type of lightA. Cleavage I. Plane polarized B. Twinkling II. Ordinary C. Twinning III. Crossed nicols D. Disperson IV. Convergent Choose the correct answer from the options given below :
Match List - I with List - II.
List - I
Optical featureList - II
Optical diagramA. Wave front (isotropic) I. Ellipse B. Wave surface (isotropic) II. Sphere C. Wave front (anisotropic) III. ellipsoidal D. Wave surface (anisotropic) IV. circle Choose the correct answer from the options given below :
- A solid crystal in which a face on one side is opposite to a point on the other, is called :
- Which of the following pairs do not have the same number of classes in their crystal system ?
- The relative abundance of a particular face of a crystal is a function of :
- In case of dipping beds, progressively younger beds occur along the directions of dip if :
Important Questions from Mixed Topic (CUET PG)
- Kalpsutra, the illustrated canonical text is from:-
- The Harappan city almost exclusively devoted to craft production was-:
- Mohandas Karamchand Gandhi launched quit India movement after the failure of:-
- The "Objectives Resolution" was introduced in constituent assembly by:-
- Who among the following was not a member of the constituent assembly:-
