How can index fossils help scientists figure out the ages of rock layers?

Answer 1

index fossils are important for index fossils because

they use them to match up rock layers in certain locations

that may be far apart!

they are ALSO important to scientists because it helps them with relative age!..

HOPE THIS HELPED:]

Answer 2

Since the organisms that became index fossils lived only during specific intervals of geologic time, geologists can estimate the ages of rock layers based on the particular index fossils they contain.

Answer 3

Index fossils are fossils of organisms that only existed during a relatively short period of time and were found globally (widespread). Since the organism was widespread and was only around for a short time, if we know when it was around, we then know how old a rock is that contains it.

• The dating of fossils was originally done by their placement in a geologic column of rock strata. Because of the Law of Superposition, the deeper the stratum, the older it is (in an undisturbed body of rock or sediment). Fossils which were evident in a particular stratum, but missing from other strata were noted as "index" fossils. The presence of these fossils indicated the age of the stratum relative to other layers. The layers of stratum were placed in a geologic column, subdivided, and assigned names based on the presence of different types of fossil organisms.This is the basis of "relative dating" of rock layers and fossils, a dating technique that was in effect until the advent of radiometric techniques in the twentieth century.
• Radiometric dating of rock involves the measurement of the amount of decay in radioactive elements which are present in the rock. Radioactive elements decay at unique rates, depending on the isotope. This rate of decay is known as half-lives, it is the time necessary for ½ of the atoms to decay in a particular element. The decay follows a geometric scale, in that in the first half-life of an element, ½ of the atoms decay, yet in the second half-life, ½ of those remaining decay and so forth. By measuring this decay, and knowing the half life of an element, scientists can date a sample. Radiometric dating is particularly useful in dating igneous and metamorphic rock.
• Because of geologic events such as plate tectonics and volcanism, suitable material for radiometric dating, such as volcanic tuff, solidified lava, and igneous intrusions have been found as layers on, in, and cut through layers of sedimentary rock. Intrusions are always younger than the rock body they penetrate, meaning that the sedimentary rock in which intrusions are found will be older than a radiometric-ally dated sample of the intrusion. Lava flows and volcanic ash which form layers in rock will be younger than the rock below and older than the rock above. The solidified intrusions and lava flows can be dated with radiometric techniques.
  
• The radiometric dating of suitable rocks (i.e. igneous or metamorphic) in proximity to their sedimentary counterparts, therefore allows the sedimentary rock to be dated as well.

Answer 4

index fossils are useful for figuring out the age of a set of disturbed rock layers by index fossils are used to determine when rock layers were formed so if they were used to figure out the age of a set of disturbed rock layers than they can also figure out when they were formed .

Answer 5

they tell the absoute age of rcoks which they occur