Pb pb dating equation
Bishop James Ussher, a 17th-century Irish cleric, for example, calculated that creation occurred in 4004 B. There were many other such estimates, but they invariably resulted in an Earth only a few thousand years old.
By the late 18th century, some naturalists had begun to look closely at the ancient rocks of the Earth.
he question of the ages of the Earth and its rock formations and features has fascinated philosophers, theologians, and scientists for centuries, primarily because the answers put our lives in temporal perspective.
Until the 18th century, this question was principally in the hands of theologians, who based their calculations on biblical chronology.
The point is that not all methods are applicable to all rocks of all ages.
One of the primary functions of the dating specialist (sometimes called a geochronologist) is to select the applicable method for the particular problem to be solved, and to design the experiment in such a way that there will be checks on the reliability of the results.
There were other estimates but the calculations were hotly disputed because they all were obviously flawed by uncertainties in both the initial assumptions and the data.
The geochronologist takes this factor into account when assigning experimental errors to the calculated ages. First, there must be no argon other than that of atmospheric composition trapped in the rock or mineral when it forms.By the early 1960s, most of the major radiometric dating techniques now in use had been tested and their general limitations were known.No technique, of course, is ever completely perfected and refinement continues to this day, but for more than two decades radiometric dating methods have been used to measure reliably the ages of rocks, the Earth, meteorites, and, since 1969, the Moon.Radiometric dating is based on the decay of long-lived radioactive isotopes that occur naturally in rocks and minerals.These parent isotopes decay to stable daughter isotopes at rates that can be measured experimentally and are effectively constant over time regardless of physical or chemical conditions.