Mt st helens radioactive dating
Such processes can cause the daughter product to be enriched relative to the parent, which would make the rock look older, or cause the parent to be enriched relative to the daughter, which would make the rock look younger.
This calls the whole radiometric dating scheme into serious question.
Geologists assert that older dates are found deeper down in the geologic column, which they take as evidence that radiometric dating is giving true ages, since it is apparent that rocks that are deeper must be older.
But even if it is true that older radiometric dates are found lower down in the geologic column, which is open to question, this can potentially be explained by processes occurring in magma chambers which cause the lava erupting earlier to appear older than the lava erupting later.
Such a large variety of igneous rocks exists that it is logical to assume an equally large variety of magmas must also exist.
However, geologists have found that various eruptive stages of the same volcano often extrude lavas exhibiting somewhat different mineral compositions, particularly if an extensive period of time separated the eruptions.
Evidence of this type led them to look into the possibility that a single magma might produce rocks of varying mineral content. Bowen discovered that as magma cools in the laboratory, certain minerals crystallize first.
This age is computed under the assumption that the parent substance (say, uranium) gradually decays to the daughter substance (say, lead), so the higher the ratio of lead to uranium, the older the rock must be.To me it has been a real eye opener to see all the processes that are taking place and their potential influence on radiometric dating.Radiometric dating is largely done on rock that has formed from solidified lava.The general idea is that many different minerals are formed, which differ from one another in composition, even though they come from the same magma.The mineral makeup of an igneous rock is ultimately determined by the chemical composition of the magma from which it crystallized.