4 laws of relative dating
Paleontology is the study of fossils and is concerned not only with their description and classification but also with an analysis of the evolution of the organisms involved.
Simple fossil forms can be found in early Precambrian rocks as old as 3,500,000,000 years, and it is widely considered that life on Earth must have begun before the appearance of the oldest rocks.
The allied field of geophysics has several subdisciplines, which make use of different instrumental techniques.
Seismology, for example, involves the exploration of the Earth’s deep structure through the detailed analysis of recordings of elastic waves generated by earthquakes and man-made explosions.
About 3,000 distinct mineral species are recognized, but relatively few are important in the kinds of rocks that are abundant in the outer part of the Earth.Earth’s rocks are composed of minerals—inorganic elements or compounds that have a fixed chemical composition and that are made up of regularly aligned rows of atoms.Today one of the principal concerns of mineralogy is the chemical analysis of the some 3,000 known minerals that are the chief constituents of the three different rock types: sedimentary (formed by diagenesis of sediments deposited by surface processes); igneous (crystallized from magmas either at depth or at the surface as lavas); and metamorphic (formed by a recrystallization process at temperatures and pressures in the Earth’s crust high enough to destabilize the parent sedimentary or igneous material).Earthquake seismology has largely been responsible for defining the location of major plate boundaries and of the dip of subduction zones down to depths of about 700 kilometres at those boundaries.In other subdisciplines of geophysics, gravimetric techniques are used to determine the shape and size of underground structures; electrical methods help to locate a variety of mineral deposits that tend to be good conductors of electricity; and paleomagnetism has played the principal role in tracking the drift of continents.