Carbon dating

This ppt explains carbon dating

1. Carbon Dating BY ASMA QURESHI 8006

2. Geochronology “ Geochronology is the science of determining the age of rocks, fossils, and sediments”

3. Commonly used techniques ▪ Radiocarbon dating ▪ Uranium–lead (U- Pb ) dating ▪ Uranium–thorium (U- Th ) ▪ Potassium–argon (K- Ar ) dating and argon–argon ( Ar-Ar ) dating

4. Radiocarbon dating Developed in the late 1940s at the University of Chicago by Willard Libby. The age of objects that were once alive can be determined by using the C-14 dating test. In this test, scientists determine how much C-14 is left in a sample and from this determine the age of the object

5. Carbon – 14 Datable Materials: Charcoal, wood, twigs, seeds, bones, shells, leather, lake mud, fabrics, soil, hair, pottery, peat, pollen, wall paintings, corals, blood residues, paper or parchment, resins

6. Radiocarbon dating

7. Origin of Carbon – 14

8. How Radioactive Dating Works:

9. 14C has a half-life of 5,730 years. In other words, after 5,730 years, only half of the original amount of 14C remains in a sample of organic material. Carbon 14 half life

10. When Living organisms die, they all have the same amount of carbon-14. When scientists find fossils they will measure how much carbon-14 it has left in its body.

11. An animal dies

12. L imitations of carbon dating Carbon dating cannot be used for samples older than 60,000 years. The material being dated must have measurable amounts of the parent or the daughter isotopes. Carbon dating can only be done on some materials, hence is not useful for determining the age of sedimentary rocks, and the method of carbon dating can be prohibitively expensive. Samples can be contaminated by other carbon-containing materials. The dates obtained from radiocarbon dating are not infallible, that is, in general, single dates should not be trusted. Thus, multiple samples need to be collected and dated.

13. Dead Sea Scroll The Dead Sea Scrolls (also the Qumran Caves Scrolls) are ancient Jewish and Hebrew religious manuscripts discovered in 1946/7 at the Qumran Caves It dates to 250-130BC according to radiocarbon dating, or 150-125BC

14. Shroud of Turin image whose image is believed to represent Jesus Christ, is one of the most popular cases where scientists used carbon dating for their investigation. In 1988, scientists determined that it originated in the 13th century, 1200 years later after the death of Jesus Christ. Shroud of Turin image

15. Metriorites After the meteorite falls to the ground, it is shielded from most (but not all ) cosmic radiation, and so the 14C that has built up in space will decay with the characteristic halflife . We can then use this signal to estimate the residence time of the meteorites on the ground. Interestingly, the time-scale for the survival of meteorites This method has been used extensively to try to understand the infall rates of meteorites

16. In situ 14C production in rocks 14C is a study of rocks exposed by the recent retreat of the Rhone Glacier in Switzerland, that shows that these rocks were exposed for about 6,500 years within the last 10,000 years, even though they were covered by ice until recently This indicates that this glacier was small in the early Holocene period, which was warmer than current conditions .

17. Archaeology The field of archaeology has relied heavily on radiocarbon dating since its inception in the early 1950’s . Many radiocarbon dates are produced which find their way into archaeological reports of various kinds.