How can we date rocks?
For date events occurring during the long history of the Earth, from its creation to the present, we use a geological time scale, also called “stratigraphic chart”.
Principle of dating Atmospheric CO2 contains mainly the stable isotope 12C, but also the isotopes 13C (stable) and 14C (unstable) in very small quantities: 1 atom 13C for 100 atoms of 12C and 1 atom 14C for 1012 atoms of 12C approximately.
The dates are carried out on rocks magmatic or metamorphic, using the rocks example, between the total system closing conditions or their isolated minerals. The age obtained is that of the closure of the system considered (mineral or rock).
Absolute dating, by giving access to the age of rocks and fossils makes it possible to measure the durations of geological phenomena. It also makes it possible to situate in time the relative scale of geological times.
There are of them major types of methods of dating : the methods of dating absolute or objective, and the methods of dating relative.
The absolute dating allows date more precisely geological events. It is based on the measurement of the variation of the isotopic ratio between the time of closure of the dated sample and the present. Its reliability depends on the quality of the samples as well as on the choice of the isotope.
Although it is possible to speak of a global stone age for all of humanity, some groups never developed metallurgical technologies and therefore remained in a stone age until they encountered technologically more developed cultures.
The Stone Age, or Stone Age, is the period of prehistory in which humans made and used stone tools and weapons, before the predominant use of metals.
The Age of Stone, or Age of Stone, is the period of prehistory during which humans made and used stone tools and weapons, before the predominant use of metals.
During the Stone Age, wood, bone, ivory, horn, and deer antlers were also used, especially at the end of the period, but stone, and especially flint, was the main material. worked to create cutting tools and weapons.