Dating fossils through strata and radiometric samples

Rated 3.94/5 based on 979 customer reviews

Isotopic dating of rocks, or the minerals in them, is based on the fact that we know the decay rates of certain unstable isotopes of elements and that these rates have been constant over geological time.It is also based on the premise that when the atoms of an element decay within a mineral or a rock, they stay there and don’t escape to the surrounding rock, water, or air.Feldspar does not have any argon in it when it forms.

If we dated a number of individual grains in the sedimentary rock, we would likely get a range of different dates, all older than the age of the rock.[SE] In order to use the K-Ar dating technique, we need to have an igneous or metamorphic rock that includes a potassium-bearing mineral.One good example is granite, which normally has some potassium feldspar (Figure 8.15).When radiometric techniques are applied to metamorphic rocks, the results normally tell us the date of metamorphism, not the date when the parent rock formed.C) can be applied to many geological materials, including sediments and sedimentary rocks, but the materials in question must be younger than 60 ka.

Leave a Reply