Geological age

GEOLOGICAL AGE (EN: geologic age; DE: geologisches Alter; FR: age geologique; ES: edad geologica; RU: возраст геологический) is the time, which has elapsed since the certain geological event (the accumulation of the layers of the rocks, the advancement of the sea, the effusion of the ancient lavas, the introduction of the intrusions, and so on). They distinguish the absolute and relative geological age. The absolute geological age is the age of the rocks, which is expressed as the absolute units of the time (as the years, usually as the millions of years). The absolute geological age is established, using various radiometric methods, according to the accumulation of the products from the decay of the radioactive elements. The numbering is performed from the modern epoch into the depth of the geological past, that is, in the descending order. This term is used conditionally to the significant extent, because the radiometric determinations of the geological age represent not only the true time of the forming of the rocks, but also the time of various subsequent superimposed processes (for example, the metamorphism). It would be better to use the terms "isotopic age", or the radiological age (see the "Geochronology" article). The relative geological age is the time of the certain events during the history of the Earth, relatively to the time of the other geological events, is determined on the basis of the mutual position of the layers within the cross section: in case of the undisturbed embedment, the lower layers are more ancient, while the upper layers are younger. According to the fossil organic remains, which are contained within the rocks, there is performed the linking of the layers to the general stratigraphic scale, and the temporal juxtaposition of the sedimentary and volcanogenic strata, which are located within the regions, which are remote one from another. The relative geological age of the geological intrusive bodies and ore veins is estimated according to the character of their interaction; the younger of these rocks breach and metamorphose the more ancient rocks, and contain the xenolith of these latter rocks.