Radiometric dating paper
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.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.A pioneering investigation into the crystallization of magma was carried out by N. At successively lower temperature, other minerals begin to crystallize as shown in Figure 3.6.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.
Radiometric dating is largely done on rock that has formed from solidified lava.
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.
Of course, there are many problems with such dating methods, such as parent or daughter substances entering or leaving the rock, as well as daughter product being present at the beginning.
Here I want to concentrate on another source of error, namely, processes that take place within magma chambers.These long time periods are computed by measuring the ratio of daughter to parent substance in a rock and inferring an age based on this ratio.