Dating establishes the chronological sequence in which sites were constructed, used and abandoned. Methods for dating objects can be divided into two categories: relative dating and absolute dating. Relative Dating: A non-scientific approach which can only establish a sequence into which the object can be placed. This will establish whether an object is older younger than other objects. Includes: Stratigraphy, typology, fluorine, and paleontological dating. Absolute Dating: Relies on scientific techniques to establish the date and is therefore more accurate. Includes: Radio-carbon dating, dendrochronology, thermo luminescence and potassium-argon. RELATIVE DATING Method Description Stratigraphy The layering of archaeological deposits, one on top of the other, over the years. The deeper in the site a layer is, the older it is. Typology Study of development of particular types of artefacts over a period of time. Classification of the artefacts according to types, based on similarities of shape, decoration and material used. Objects are arranged to form a sequence, showing how their forms developed and changed. Fluorine dating Used in dating bones. Bones absorb fluorine from damp soil. Bones can be checked against a fluorine test. Paleontological dating Based on the history of animal life. Palaeontologists know when certain species appeared or became extinct. When their bones are found at a site a rough date can be given. ABSOLUTE DATING Method Description Radio carbon dating Based on measurement of the radioactive carbon content of organic materials. Dendrochronology Uses tree rings to date objects made of wood and is remarkably precise. Trees show a growth ring for every year of their life, and the thickness of the rings is subject to seasonal variations. Thermoluminescence Used for ceramic artefacts. Mineral crystals accumulate and store energy which is released when they are heated. By heating a sample of pottery and measuring the amount of energy released, the time that has elapsed since the pot was last fired can be calculated. Potassium-argon Used to date volcanic rock. The amount of argon gas remaining as potassium in rock decays at a fixed rate can be measured to determine the age of the rock.