Further, he proposed that wherever uncontorted layers were exposed, the bottom layer was deposited first and was, therefore, the oldest layer exposed; each succeeding layer, up to the topmost one, was progressively younger.The Major Divisions of Geologic Time are shown here, arranged in chronological order with the oldest division at the bottom, the youngest at the top. Specifically, stratigraphy refers to the application of the Law of Superposition to soil and geological strata containing archaeological materials in order to determine the relative ages of layers.
The most compelling argument for an age of the earth of 4.5 billion years are the large number of independent tests that have been used to confirm this date.
These tests have been performed on what are thought to be the earth's oldest surviving rocks, meteorites, and moon rocks.
These tests have consistently given the same ages for each of these objects.
Examples of a number of consistent dates derived from different methods are given.
Many of these links also appear where appropriate below.
James Hutton and William Smith advanced the concept of geologic time and strengthened the belief in an ancient world.
For each dating or chronological method there is a link in the box at right to take you to that section of this page.
There, you will find a brief description of the method, plus links to take you to other webpages with more extensive information.
Dating is not necessary to demonstrate that evolution is a fact.
Chronological sequence is all that is really required.
A short but clear explanation about radioactive isotopes commonly used for determining ages of rocks (with graphics) and putting numbers on the geologic time scale, extending it back before the occurance of abundant index fossils.