Geologic dating issues dating cues
The Discovery of Deep Time Pre-modern concepts of Time Geology and the discovery of Deep Time Geology and the discovery of Deep Time - Reading List Geological Timescale Stratigraphy Radiometric dating Detailed Geological Timescale Precambrian Time Phanerozoic Eon Geological Time Units The Geon Planetary Timescales Lunar Geological timescale Martian Geological timescale Glossary References Quaternary Time Historical Time Although (as explained in the parent unit (more inclusive unit) of this topic) there are many possible timescales (which range from the very long (billions of years) to the very short) , Geological time, which deals in millions or tens of millions of years, is the main focus here at Palaeos.
Therefore this page provides the starting point for an overview of Earth history.
Lava (properly called magma before it erupts) fills large underground chambers called magma chambers.
Most people are not aware of the many processes that take place in lava before it erupts and as it solidifies, processes that can have a tremendous influence on daughter to parent ratios.
Prior to 1905 the best and most accepted age of the Earth was that proposed by Lord Kelvin based on the amount of time necessary for the Earth to cool to its present temperature from a completely liquid state.
Here I want to concentrate on another source of error, namely, processes that take place within magma chambers.
The only problem is that we only know the number of daughter atoms now present, and some of those may have been present prior to the start of our clock. The reason for this is that Rb has become distributed unequally through the Earth over time.
We can see how do deal with this if we take a particular case. For example the amount of Rb in mantle rocks is generally low, i.e. The mantle thus has a low If these two independent dates are the same, we say they are concordant.
(more on these subdivisions) We know these intervals lasted for millions of years, or even tens or hundreds of millions, because they can be dated them with a fair degree of accuracy according to the amount of radioactivity that occurs in the rocks.
We even have a rough idea of geological timescales on the moon and Mars.