Process of radiometric dating

11-Feb-2020 11:34 by 8 Comments

Process of radiometric dating

This process of changing one element (designated as the parent isotope) into another element (referred to as the daughter isotope) is called radioactive decay.

So, in general, few people quarrel with the resulting chemical analyses.

It is the interpretation of these chemical analyses that raises potential problems.

To understand how geologists “read” the age of a rock from these chemical analyses, let’s use the analogy of an hourglass “clock” (Figure 2).

So, for example, every carbon atom contains six protons and six electrons, but the number of neutrons in each nucleus can be six, seven, or even eight.

Therefore, carbon has three isotopes (variations), which are specified carbon-12, carbon-13, and carbon-14 (Figure 1).

In some cases, the isotopes eject particles, primarily neutrons and protons.

(These are the moving particles measured by Geiger counters and the like.) The end result is a stable atom, but of a different chemical element (not carbon) because the atom now has a different number of protons and electrons.

So, after only half an hour, half the sand should be in the top bowl, and the other half should be in the bottom bowl.

Suppose that a person did not observe when the hourglass was turned over.

Note that the carbon-14 (or radiocarbon) method is not used to date rocks because most rocks do not contain carbon. They must find rocks that have the isotopes listed above, even if these isotopes are present only in minute amounts.

Most often, this is a rock body, or unit, that has formed from the cooling of molten rock material (called magma).

In an hourglass, grains of fine sand fall at a steady rate from the top bowl to the bottom.