Dating Methods Essay -- essays papers

General Differances Between Relative and haughty Dating Methods get dates for fogeys that atomic number 18 prove in sites beingexcavated by anthropologist is very important. Dates tape theevolution from early hominid specimens to our own species, Homohomo sapiens. at that place be many methods that can be used to acquirethese dates, merely all of these methods fall into virtuoso of twocatorgories. They can either cast a unquestioning date or a relativedate. An absolute date is champion in which you get an actual date in historic period. Also slamn as chronometric methods. Relative dates donot go bad an actual date in terms of years, but they tell you ifone fossil is older or younger than another fossil.Ushally relative dates are given in terms of the tower ofearth they are set in. This is called striatigraphy. Insites like Olduvai gorge their are geological layers of vocanicash and sediment. When a anthropologist finds a fossil in aundistirbed layer of gray as h, you know that it is younger thanthe fossil in the layer of red ash downstairs, and that fossil isyounger than the fossil in the layer of brown ash belowit.(Johanson 65) The basic theory here is that a certian sitecantians a geolgical column key that is made up of differantstrata layers, the fossils get older as they transport down the key,and are found in differant layers of strata..(Scully 2) Relative dates withstand a couple of major problems. One is that theearth moves in many shipway and this can distrube the layers ofsediment putting younger fossils below older ones. other isthat you can not tell exactly how much younger or older somethingis from somethinng else and you can not date differant fossilsfrom differant sites with thes relative dating methods. Absolute dating, unlike realative dating, gives theanthropologist an exact date in terms of calander years. Thesedating methods are much more reliable and can be used in manydifferant sites with many differant fos sils. Absolute datingbases its dates on the essential radioactivity of differantelements found in the world.(Johnston 216) There are certianelements that occur in differant forms, these elements are calledisotopes. Each one of these isotopes has a differant atomic massthan others. roughly of thes isotopes are radioactive, meaning thatthey give of radiation in either important or beta form, as theyde... ... has a half-life.C14 is the radioactive isotope of rearular one C, c12. Thecocentration of C14 in the torso is one billionth of a gram in thebody to one gram of C12. This C14 is contantly decaying, butthrough animals and plants breathing it is replenashed when anorganism is alive. When the animal dies the C14 recess stops anda decay that is not replenashed.(Comas 456) During life an organism have a specific activity of 15.6disintigrations per minuate per gram of regular carbon in thierbody.(Comas 456) After life and C14 intake cease and theequilibrium is halted, radioactive disintigration of C14 occurs,and by and by 5,700 years this activity will have decreased to 7.8disintigratuions per minuate per gram of carbon in thebody.(Comas 457) This means that the ratio of C14 to C12 leftin the fossil when it is found can give a date in years. Carbon-14 dating has a half-life of 5,700 years, with the lowerlimit of 1,000 years. The upper limit used to be about 30,000years because after that the ratio was too small to analis. lately reaserch by Haring and deVires has let scientist put theupper limit at 100,000 years old.(Comas 457)