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4 Cards in this Set
- Front
- Back
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Fossil Formation |
- Parts of organisms may become fossilised when they are buried by drifting sand, mud deposited by rivers, volcanic ash. - Nature of the soil is very important for the fossilisation of bone. In wet, acid soils the minerals in the bone are dissolved and no fossilisation occurs. - However, if such soil contains no oxygen, complete preservation of the soft tissues of the animal as well as the bones may occur. |
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Dating of Fossils |
- The excavation of fossils or artefacts is to determine the age of the material. This is known as dating. - Age is crucial in finding out the sequence of changes. |
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Absolute Dating (Potassium Argon) |
- This technique is based on the decay of radioactive potassium to form calcium and argon. - Such different forms (forms with atomic weights: 39, 40 and 41) of the same element, with different numbers of neutrons in the nucleus of their atoms, are called isotopes. - Such decay takes place at an extremely slow but constant rate. |
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Absolute Dating (Carbon 14) |
- Method is based on the decay of the radioactive isotope of carbon, carbon-14, to nitrogen. - When green plants use atmospheric carbon dioxide in photosynthesis, one atom in every million x million of the carbon atoms incorporated in the plant tissues is carbon-14. |
