The samples are crushed to sand and granule size, thoroughly mixed to homogenise the material and a smaller subsample selected.
It must also be assumed that all the daughter isotope measured in the rock today formed as a result of decay of the parent.
This may not always be the case because addition or loss of isotopes can occur during weathering, diagenesis and metamorphism and this will lead to errors in the calculation of the age.
allows us to indirectly date fossils up to billions of years old based on minerals in surrounding layers b.
can be used to directly date fossils up to 3 billion years old c. allows us to indirectly date fossils up to billions of years old based on minerals in surrounding layers b.
relies on the fact that the daughter isotope decays to the parent isotope at a constant rate d. can be used to directly date fossils up to 3 billion years old c.
relies on the fact that the daughter isotope decays to the parent isotope at a constant rate d. allows us to determine an absolute, errorless date Yet another homework question written by somebody who doesn't know much about radiometric dating. a - is incorrect because there are very few fossils "billions" of years old, and the principal of radiometric dating is based on radioisotopes not minerals.
b - is incorrect because radiometric dating can not be used to date fossils directly c - is incorrect because the parent isotope decays to the daughter isotope d - is incorrect because radiometric dating works just fine on rocks billions of years old, eg K/Ar e - is incorrect because a perfectly errorless determination in science is a rare thing.
The discovery of radioactivity and the radiogenic decay of isotopes in the early part of the 20th century opened the way for dating rocks by an absolute, rather than relative, method.
This dating method is principally used for determining the age of formation of igneous rocks, including volcanic units that occur within sedimentary strata.
It is also possible to use it on authigenic minerals, such as glauconite, in some sedimentary rocks.
The amount of deflection will depend upon the atomic mass of the particles so different isotopes are separated by their different masses.