Dating Fossils and Rocks

1. Dating Fossils and Rocks

2. Topics • Carbon-14 dating • Radioisotope dating • The Biblical age of the earth

3. The Atom • Fundamental unit of matter • Made up of components called subatomic particles • Proton (positive charge) • Neutron (no electrical charge) • Electron (negative charge) Nucleus Electron

4. What is Carbon?

5. Carbon has unique properties that are essential for life on earth. • Familiar to us as: • the black substance in charred wood, • as diamonds, • and the graphite in ‘lead’ pencils, • also

6. carbon comes in several forms, or isotopes. • One rare form has atoms that are 14 times as heavy as hydrogen atoms:

7. Carbon-14 is also referred to as: • C-14 • Carbon-14 14 • C • Radiocarbon Atomic mass 16 6 14 6 9 6 C C C Atomic number • Types of carbon (isotopes)

8. Atomic Mass • The atomic mass (ma) is the mass of an atom at rest, most often expressed in unified atomic mass units. • The atomic mass may be considered to be the total mass of protons, neutrons and electrons in a single atom (when the atom is motionless).

9. Atomic Number • The atomic number (also known as the proton number) is the number of protons found in the nucleus of an atom. • It is traditionally represented by the symbol Z. • The atomic number uniquely identifies a chemical element.

10. In an atom of neutral charge, the number of electrons also equals the atomic number. • The atomic number is closely related to the mass number, which is the number of protons and neutrons in the nucleus of an atom. • The mass number defines the isotope of the element and often comes after the name of the element, e.g. carbon-14 (used in carbon dating).

11. 14 7 N 14 6 C What is Radioactive Decay? • The nucleus of an atom changes into a new element • The proton number (atomic number) must change • A neutron changes into a proton

12. How C-14 is Produced

13. Carbon-14 is made when cosmic rays knock neutrons out of atomic nuclei in the upper atmosphere. • These displaced neutrons, now moving fast, hit ordinary nitrogen (14N) at lower altitudes, converting it into 14C. • Unlike common carbon (12C), 14C is unstable and slowly decays, changing it back to nitrogen and releasing energy. • This instability makes it radioactive.

14. Ordinary carbon (12C) is found in the carbon dioxide (CO2) in the air, which is taken up by plants, which in turn are eaten by animals. • So a bone, or a leaf or a tree, or even a piece of wooden furniture, contains carbon. • When the 14C has been formed, like ordinary carbon (12C), it combines with oxygen to give carbon dioxide (14CO2), and so it also gets cycled through the cells of plants and animals.

15. Cosmic Rays (radiation) C-14 combines with oxygen to form carbon dioxide (CO2) Forms C-14 Collision with atmosphere (N14) How C-14 is Produced

16. We can take a sample of air, count how many 12C atoms there are for every 14C atom, and calculate the 14C/12C ratio. • Because 14C is so well mixed up with 12C, we expect to find that this ratio is the same if we sample a leaf from a tree, or a part of your body.

17. Changing N-14 into C-14

18. No more C-14 intake How the Carbon Dating Clock Works • Once a plant or animal dies the clock starts • The plant or animal no longer takes in C-14 • The C-14 present in the plant or animal begins to decay C-14 continues to decay

19. In living things, although 14C atoms are constantly changing back to 14N, they are still exchanging carbon with their surroundings, so the mixture remains about the same as in the atmosphere. • However, as soon as a plant or animal dies, the 14C atoms which decay are no longer replaced, so the amount of 14C in that once-living thing decreases as time goes on. • In other words, the 14C/12C ratio gets smaller.

20. So, we have a ‘clock’ which starts ticking the moment something dies. • Obviously, this works only for things which were once living. • It cannot be used to date volcanic rocks, for example.

21. Carbon-14 Life Cycle

22. The rate of decay of 14C is such that half of an amount will convert back to 14N in 5,730 years (plus or minus 40 years). • This is the ‘half-life.’ • So, in two half-lives, or 11,460 years, only one-quarter will be left.

23. 14 6 14 7 14 7 C N N 5,730 year half-life Carbon-14 Life Cycle Cosmic radiation

24. Carbon-14 Dating

25. Thus, if the amount of 14C relative to 12C in a sample is one-quarter of that in living organisms at present, then it has a theoretical age of 11,460 years. • Anything over about 50,000 years old, should theoretically have no detectable 14C left. • That is why radiocarbon dating cannot give millions of years. • In fact, if a sample contains 14C, it is good evidence that it is not millions of years old.

26. However, things are not quite so simple. • First, plants discriminate against carbon dioxide containing 14C. • That is, they take up less than would be expected and so they test older than they really are. • Furthermore, different types of plants discriminate differently. • This also has to be corrected for.

27. Second, the ratio of 14C/12C in the atmosphere has not been constant—for example, it was higher before the industrial era when the massive burning of fossil fuels released a lot of carbon dioxide that was depleted in 14C. • This would make things which died at that time appear older in terms of carbon dating. • Then there was a rise in 14CO2 with the advent of atmospheric testing of atomic bombs in the 1950s. • This would make things carbon-dated from that time appear younger than their true age.

28. Measurement of 14C in historically dated objects (e.g., seeds in the graves of historically dated tombs) enables the level of 14C in the atmosphere at that time to be estimated, and so partial calibration of the ‘clock’ is possible. • Accordingly, carbon dating carefully applied to items from historical times can be useful.

29. However, even with such historical calibration, archaeologists do not regard 14C dates as absolute because of frequent anomalies. • They rely more on dating methods that link into historical records. • Outside the range of recorded history, calibration of the 14C clock is not possible.

30. Carbon-14 Dating • Used only on organic material • Cannot be used to date rocks • Maximum age limit about 60,000 years

31. Quantity of C-14 in a Fossil The C-14 dating method relies on measuring the amount of C-14 in the fossil • If there is a lot of C-14 remaining in the fossil, we assume it has not been dead very long • If there is very little C-14 remaining in the fossil we assume most of it has decayed and the animal lived a long time ago (i.e. 30,000 or more years)

32. What Do We Need to Know? We need to know two things • How fast C-14 decays (measured in half-lives - this is known: 5,730 years) • The starting amount of C-14 in the fossil We know number 1 How can we know how much C-14 was in an organism 5,000 years ago?

33. Calculating the Starting Amount of C-14 • The dating method relies on measuring the ratio of carbon-12 to carbon-14 in the sample • The ratio today in the atmosphere is 1-trillion to 1

34. Amount of stable C-12 Amount of unstable C-14 Ratio Years Dead # Half-lives 100 Trillion 100 1-T to 1 0 0 50 5,730 100 Trillion 1 2-T to 1 100 Trillion 11,460 25 2 4-T to 1 100 Trillion 8-T to 1 17,190 3 12.5 100 Trillion 4 22,920 6 16-T to 1 3 28,650 100 Trillion 32-T to 1 5 Determining the Age from the C-12/C-14 Ratio Are there any assumptions in this process?

35. The Underlying Assumption Has the ratio of C-12 to C-14 in the atmosphere always been the same? If YES, then the C-14 dating is valid for up to 60,000 years If NO, then we have no valid way of knowing the starting amount of C-14 and dates will be invalid 30,000 years to reach equilibrium

36. Dr. William Libby Richard, Milton, Shattering the Myths of Darwinism, 1997, p. 32. (W. F. Libby, Radiocarbon Dating, 1955) “He found a considerable discrepancy in his measurements indicating that, apparently, radiocarbon was being created in the atmosphere somewhere around 25 percent faster than it was becoming extinct. Since this result was inexplicable by any conventional scientific means, Libby put the discrepancy down to experimental error.”

37. Experiments on Equilibrium “During the 1960s, Libby’s experiments were repeated by chemists… The new experiments, though, revealed that the discrepancy observed by Libby was not merely an experimental error – it did exist.” Richard, Milton, Shattering the Myths of Darwinism, 1997, p. 32.

38. Experiments on Equilibrium “There is strong indication, despite the large errors, that the present natural production rate exceeds the natural decay rate by as much as 25 percent.” Richard Lingenfelter, “Production of C-14 by cosmic ray neutrons”, Review of Geophysics, 1963, p.51.

39. New Techniques Show Young Dates Walter Brown (Ph.D. Mechanical Engineering and Professor of Physics), In the Beginning, 2001, p. 245. “The new atomic accelerator technique has consistently detected at least small amounts of carbon-14 in every specimen – even materials that evolutionists claim are millions of years old, such as coal… In one study of eleven sets of ancient human bones, all were dated at about 5,000 radiocarbon years or less.”

40. Problem with the Calculating of the Starting Amount of C-14

41. The amount of cosmic rays penetrating the earth’s atmosphere affects the amount of 14C produced and therefore dating the system. • The amount of cosmic rays reaching the earth varies with the sun’s activity, and with the earth's passage through magnetic clouds as the solar system travels around the Milky Way galaxy.

42. A stronger magnetic field deflects more cosmic rays away from the earth. • Overall, the energy of the earth’s magnetic field has been decreasing, so more 14C is being produced now, than in the past. • This will make old things look older than they really are.

43. Also, the Genesis flood would have greatly upset the carbon balance. • The flood buried a huge amount of carbon, which became coal, oil, etc., lowering the total 12C in the biosphere (including the atmosphere—plants regrowing after the flood absorb CO2, which is not replaced by the decay of the buried vegetation). • Total 14C is also proportionately lowered at this time, but whereas no terrestrial process generates any more 12C, 14C is continually being produced, and at a rate which does not depend on carbon levels (it comes from nitrogen).

44. Therefore, the 14C/12C ratio in plants/animals/the atmosphere before the flood had to be lower than what it is now. • Unless this effect (which is additional to the magnetic field issue just discussed) were corrected for, carbon dating of fossils formed in the flood would give ages much older than the true ages.

45. Conclusion on Carbon-14 Dating

46. The key assumption has been shown to be false (equilibrium) • Carbon-14 dating is a reliable dating method for less than 3,000 years and not the claimed 60,000 found in many textbooks • Carbon-14 dating is based on an assumption

47. Radioisotope Dating Methods What are they and how do they operate? What is the basic perception? How accurate are they? Are there any hidden assumptions?

48. Education Biology: Visualizing Life, Holt, Rinehart, Winston, 1998, p.177. “Using radioactive dating, scientists have determined that the Earth is about 4.5 billion years old, ancient enough for all species to have been formed through evolution.”

49. Education National Association of Biology Teachers (NABT), 1995 Position Statements. “Radiometric and other dating techniques, when used properly, are highly accurate means of establishing dates in the history of the planet and in the history of life.”

50. There are various other radiometric dating methods used today to give ages of millions or billions of years for rocks. • These techniques, unlike carbon dating, mostly use the relative concentrations of parent and daughter products in radioactive decay chains.