Radiocarbon Dating in Archeology
The scientific discipline of archeology has undeniably enriched mankind’s history and has helped to slake the quest to understand our past civilizations in a better manner. Understanding the age and period of being of the excavated dodos and other organic objects will assist the archeologist to unravel human history and development in a scrupulous mode ( Taylor 24 ) . Archeologists utilize one of the radical methods called the wireless C dating to find the approximative age of the organic stuffs including works and animate being parts up to 50000 old ages ( Long ) .
Radiocarbon dating technique is chiefly based on the radioactive decay of Carbon-14 isotope. Developed by a squad of research workers under the leading of Dr. Willard Libby, this technique had revolutionized the manner the archeological promotions are made in larning about the past civilisation and civilizations, alterations occurred in the Earth and in its clime. Radiocarbon dating enable archeologists to supply cogent evidence of genuineness to the excavated artifacts’ period of use and therefore by join forcesing with the attempts with historiographers and anthropologists, the unwritten history can be exactly explained.
Desmond Clark ( 1979 ) sentiments that if wireless C dating technique were non discovered,“ we would still be fall throughing in a sea of imprecisenesss sometime bred of divine guessing but more frequently of inventive guess ”( Clark, 1979:7 ) . Harmonizing to Higham ( 1999 ) C14 method can be described as ‘the wireless C revolution’ which has significantly impacted our understanding about development and besides cultural outgrowth of human species. Taylor ( 1987 ) suggests C-14 technique as one of the most important finds of 20thcentury that touches the kingdom of many subjects including archeology. Prior to the development of carbon 14 dating it was hard to find the age of the artefacts unless it was accompanied with some chronologically specific things like a coin. Otherwise archeologists had to fall back T to the method of comparative dating where by comparing with stratigraphically close objects [ objects which are buried at the same deepness will be about of the same epoch. ] clue sing the clip period and historical manners were assumed or instead guesstimated. But the coming of carbon-14 dating tools has opened up the new range of absolute dating where scientists could foretell the age of excavated artefacts and objects with great preciseness up to 50,000 old ages old. For illustration, if a tree was found to be used in an excavated piece of architecture, by finding the age of the tree or the period when the tree was cut down for building, the epoch to which the excavated architecture precisely belongs can be estimated ( Michels, J W ) .
The Method of Carbon-14 Technique
Archeologists rely on the assorted radiometric dating techniques- based on the radioactive belongingss of unstable chemical atoms to find the age of the stuffs.
Research workers from the field of Physicss have discovered that radioactive molecules are unstable and they undergo decay to achieve a stable construction at a particular rate which is straight determined by the atomic figure and mass of the decaying atom ( Polach, H.A and. Currie, L.A ) . Based on this invariable of the radioisotope of C, 14-C or C -14 the age of the organic stuff is assessed. In the biosphere carbon-14 is created by the hit of a neutron, exited by the cosmic beam collides with a N atom. The isotope of C therefore produced is radioactive and it will undergo decay at a changeless rate ( Berger and H.E Suess ) . The C isotope is besides absorbed during photosynthesis by workss and ranges animal organic structure when they consume works parts. It besides reaches the beings through respiration along with normal carbon-12. It is assumed that in a life object carbon-14 which undergoes decay is replaced at a steady rate. The C dating technique takes the premise that all lifes have reasonably same per centum of 14C isotope in their organic structure and besides that the ratio of carbon-12 to carbon -14 nowadays in the biosphere and inside the life workss and animate beings remain changeless. After the decease of the being the C consumption is stopped. Then the sum of carbon-12 in the organic structure will non cut down but the sum of carbon-14 undergoes decrease due its radiation. Carbon-14 isotope will undergo decay at an exponential rate to organize the stable nitrogen-14.Thus by comparing the comparative measure of C -12 and C -14 in an organic affair excavated scientists can foretell the age of the object ( R.E Taylor and M.J Aitken ) . The undermentioned equation is used to find the carbon-14 decay.
Where N is the current sum, N_o is the original sum, lambda is the proportionality invariable for the growing rate ( which is negative for decay ) , and T is the sum of clip that has passed.
Figure: 1 Carbon -14 lifecycle.
Beginning: ( Brain, 2014 )
The half life of carbon-14 is 5730 old ages. This implies that it takes 5730 old ages for half of the 14C atoms in the organic affair to acquire decayed. When an being is dead the consumption of the carbon-14 Michigans and in a 5730 twelvemonth clip period, half of the sum of carbon-14 nowadays in the organic affair would hold undergone beta decay to organize stable Nitrogen-14. The combustion of a little piece of the excavated organic affair and mensurating the negatrons emitted during the procedure by the disintegrating carbon-14 by radiation counters enable to quantify the sum of C -14 nowadays in the stuff. This information will assist the scientists to relationship of Nitrogen-14 and Carbon-14 atom and can be used to foretell the age of the artefact straight.
This method assumes that the ratio of C-14 to C-12 in the ambiance and in the life being will be a changeless. But surveies have showed a little fluctuation in this ratio over the millenary and hence there is a possibility and attendant disagreement in computation excessively ( Currie ) . Another restriction is the trouble in gauging the age of things which are older than 50000 old ages as the sum of C-14 in such samples become perfectly undetectable due to finish decay.
Despite all the restrictions radio C dating will stay as a important tool for archeologist around the Earth to compare and understand the development of human civilization and civilisation. Promotions in this field like gas pedal techniques of carbon-14 dating ( C. Tuniz, J.R Bird, D.Fink, and G.F Herzog 60 ) conducted with the aid of mass spectrometer have increased the scope of the technique up to 100000 old ages ( Nave ) . Therefore doubtless radiocarbon dating remains one of the important tools for the archeologist to explicate the development and cultural outgrowth in a more accurate mode.
Brain, Marshall. “ How Carbon-14 Dating Works. ” 03 October 2000. HowStuffWorks.com.
& A ; lt ; hypertext transfer protocol: //science.howstuffworks.com/carbon-14.htm & A ; gt ; 18 March 2009.
Berger and H.E Suess ( eds. ) . University of California Press, Los Angeles.. 1979: Pp. 7-31. Print
Clark, J.D. Radiocarbon Dating and African Prehistory. In,Radiocarbon Dating. Proceedingsof the Ninth International Conference, Los Angeles and La Jolla, 1976.
Currie, LLoyd A. “ The Remarkable Metrological History Of Radiocarbon Dating [ II ] . ” Journal of Research of the National Institute of Standards and Technology 109.2 ( 2004 ) : 185-217
Higham, Thomas. “ The Method. ” 1999. hypertext transfer protocol: //www.c14dating.com/int.html.04 Nov 2014.
Long, Kelly. “ Why Is Radiocarbon Dating Important to Archaeology. ” California State Parks. & A ; lt ; hypertext transfer protocol: //www.parks.ca.gov/ ? page_id=24000 & A ; gt ; 1 March 2009.
Michels, J W. Dating methods in archeology. Seminar Press, 1973.
Nave, R. “ Accelerator techniques for C dating. ” & amp ; lt ; hypertext transfer protocol: //hyperphysics.phyas tr.
gsu.edu/hbase/nuclear/cardat.html & A ; gt ; 15 April 2009.
Polach, H.A and. Currie, L.A. Exploratory analysis of the international carbon 14 cross- standardization informations: consensus values and interlaboratory mistake. Preliminary note.Radiocarbon,. 1980: -35-933.Print.
Taylor, R.E. 1987. Radiocarbon Dating. An archeological position. Academic Press, Orlando, USA.
Taylor R.E and M.J Aitken. ( explosive detection systems ) 1997.Chronometric dating in Archaeology. Progresss inArchaeological and Museum Science, volume 2.Oxford University, England
Tuniz, J.R Bird, D.Fink, and G.F Herzog..Accelerator Mass Spectrometry: Ultrasensitiveanalysis for planetary scientific discipline.CRC Press. 1998.