# Atomic dating using isotopes lab report

Al is produced from argon in the atmosphere by spallation caused by cosmic-ray protons.

Aluminium isotopes have found practical application in dating marine sediments, manganese nodules, glacial ice, quartz in rock exposures, and meteorites.

In a separate article (Radiometric dating), we sketched in some technical detail how these dates are calculated using radiometric dating techniques.

As we pointed out in these two articles, radiometric dates are based on known rates of radioactivity, a phenomenon that is rooted in fundamental laws of physics and follows simple mathematical formulas.

Radiometric dating is self-checking, because the data (after certain preliminary calculations are made) are fitted to a straight line (an "isochron") by means of standard linear regression methods of statistics.

The slope of the line determines the date, and the closeness of fit is a measure of the statistical reliability of the resulting date.

In the particular case that Morris highlighted, the lava flow was unusual because it included numerous xenoliths (typically consisting of olivine, an iron-magnesium silicate material) that are foreign to the lava, having been carried from deep within the earth but not completely melted in the lava.

Several hundred laboratories around the world are active in radiometric dating.

We scientists who measure isotope ages do not rely entirely on the error estimates and the self-checking features of age diagnostic diagrams to evaluate the accuracy of radiometric ages.

Whenever possible we design an age study to take advantage of other ways of checking the reliability of the age measurements.

Essentially all of these strongly favor an old Earth.

Radioactive decay rates have been measured for over sixty years now for many of the decay clocks without any observed changes.