When scientists at the University of Regina, Saskatchewan were asked what the results would be if these roots were dated by Potassium Argon method.

With the exception of Carbon-14, radiometric dating is used to date either igneous or metamorphic rocks that contain radioactive elements such as uranium. Now when the uranium or thorium disintegrates, the alpha particles which are emitted are slowed down by the crystals in which the grains of the uranium- or thorium-bearing minerals are embedded.

And even though various radioactive elements have been used to "date" these rocks, for the most part, the methods are basically the same. This means that if you had some pure uranium-238 with no lead in it, 4.5 billion years later one half of it would have decayed into its stable daughter product (lead-206). Where these alpha particles finally stop, crystal deformation occurs (and) shows up as a discolouration or a darkening of the crystals.

They consist of measuring the amount of radioactive (mother) element and comparing it to the amount of stable (daughter) element. Uranium is radioactive, which means it is in the process of changing from an unstable element into a stable one. And after 9 billion years there would be 75% lead and 25% uranium, and so on. (an) episode of drastically accelerated decay has ... When the crystal is looked at under a microscope, these discolourations appear as dark ringshence the name "pleochroic halo".

Few people realize it but all radiometric dating methods require making at least three assumptions. Now the magnitude of the radius of a pleochroic halo in a particular mineral depends on the amount of energy that the alpha particle has ... depends on the half-life of the particular decay responsible for this alpha particle emission.

The second assumption is much more speculative since there is no way to verify whether or not some (or most) of the daughter element was already present when the rock solidified. However, in some cases, a few scientists are telling us that they have solved this problem.

For example, with the uranium/lead method scientists have attempted to estimate what the original ratio (of uranium-238 to lead-206) was when the Earth formed.This is because "common" lead contains both radiogenic (lead 206, 207 and 208) and non-radiogenic lead (204) but it does not contain any uranium.In fact, about 98% of common lead is "radiogenic" (containing lead 206, 207, 208) and only 2% non-radiogenic.College Board Standards for College Success: Science ES.3 Earth’s History: Relative and Absolute dating.Students understand that various dating methods — relative and absolute — have been used to determine the age of Earth. Between Earth Science and Other Disciplines: Evidence of Common Ancestry and Divergence (LS.1.1); Living Systems and the Physical Environment (LS.3.1); Nuclear Chemistry (C.1.6); Nuclear Interactions and the Conservation of Mass–Energy (P.2.3) Benchmarks: American Association for the Advancement of Science.To do this they have selected a certain meteorite, which contained various types of lead (including lead 204, 206, 207 and 208) but no uranium, and they have assumed that this ratio is equivalent to the earth's original lead ratio.