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Before the advent of absolute dating methods in the twentieth century, nearly all dating was relative.The main relative dating method is stratigraphy (pronounced stra-TI-gra-fee), which is the study of layers of rocks or the objects embedded within those layers.Dating techniques are procedures used by scientists to determine the age of an object or a series of events.The two main types of dating methods are relative and absolute.What Halley's work accomplished was to make the idea of the Earth having a physical history that was older than human history (but not infinitely old) philosophically acceptable.What makes Buffon's estimate stand out is that he not only posited a physical process that required a finite time to occur (the time for the Earth to cool from a hot molten state), but performed experiments designed to help him make the best possible estimates. The British physicist Lord Kelvin refined Buffon's calculation in 1862 ( of the age of the Earth by this means because they do not take into account natural radioactivity in rocks (which Kelvin did not know about) that makes the Earth warmer that it would be in the absence of any other sources of heat.
It was not until the 1890s that the Irish geologist John Joly computed an age of about 80-90 Million years using Halley's method, an understimate as it does not take into account the various ways that salts are naturally removed from the oceans.This provided a way out of Hutton's dilemma, but it is still somewhat limited in its utility for measuring the ultimate age of the Earth, even if it does give an idea of the geologic ages of particular parts of the Earth. Thus, if you find Lead isotops inside Zircon, the only way it could get there is as the daughter product of Uranium decay.The Zircon will thus start out with no Lead of any form, but small amount of Radiometric Dating is the use of radioactive isotopes to measures the ages of rocks (or, more specifically, of minerals in the rocks).In Christianity & Islam, scholars took up the effort to fix the date of the Creation described in Genesis, and so fix the age of the Earth.Contrary to many accounts, Ussher did not give a specific time of day, although you will often read that he gave the time of creation as "9am".Since certain species of animals existed on Earth at specific times in history, the fossils or remains of such animals embedded within those successive layers of rock also help scientists determine the age of the layers.Similarly, pollen grains released by seed-bearing plants became fossilized in rock layers.The Earth was thus millions of years old, but Hutton concluded (incorrectly) that the repeated cycles of decay & repair have effectively erased this history from the geologic record.In Hutton's memorable words Lyell introduced the idea of Stratigraphic Ages for geological formations still in use (in modified form) today. But, while Uranium can be trapped in Zircon at formation, Lead is strictly excluded chemically.The traditional Jewish calendar starts from 3760 BC, which is taken to be a date for the creation of the Earth.A belief in a unique event of creation makes it meaningful to talk about the "age of the Earth" in this context.