Consequently, at any given time the % of parent atoms which decay is constant.In other words, radioactive decay is a Constant Rate Process.The number of parent atoms that decay in a fixed period of time, or conversely the number of daughter atoms produced, depends on the number of parent atoms present at any point in time.
This concept is illustrated in the diagram to the left.
(Greek lamda) is the radioactive decay constant (a number defining the probability that an atom will spontaneously decay in a given time period).
In order to use this equation for decay over a given time period, we will need the solution of a first-order differential equation.
The Geologic Time Scale (courtesy of the Geological Society of America) UC (Berkeley) Museum of Paleontology Exhibit on Geologic Time For an informative description of the historical development of the Geologic Time Scale and the principles of geology that have been used to develop it, please visit the Berkeley Museum of Paleontology web page cited above.
I also encourage you to visit the links within the Berkeley page to learn more about the divisions (Eras, Periods, etc.) of the time scale, their stratigraphy, life forms and other useful bits of information. Students will learn about the principles of Stratigraphy and application of various techniques.
Our ability to interpret and understand geologic events has been significantly enhanced by the development of various tools which allow us to determine the absolute age of many rocks and/or minerals.There are several different techniques and approaches possible, but all rely on the principles of radioactive decay of unstable isotopes of elements present in trace quantities in many rocks and minerals.As an example, consider Carbon: All atoms of Carbon consist of 6 protons and 6 electrons.The different isotopes, C-12, C-13 and C-14 differ in the number of neutrons in the nucleus, and consequently differ in atomic weight.Isotopes are either stable (do not break down spontaneously) or unstable (spontaneously break down, or decay, by nuclear reactions). However, small quantities of radioactive C-14 are produced in the Earth's upper atmosphere by interaction of cosmic rays with nitrogen according to the following reaction: In radioactive decay reactions, the unstable isotope is referred to as the parent and the element produced by the decay reaction is called the daughter.For each atom of a radioactive isotope there is a fixed and constant probability that it will decay in a fixed period of time.