http://www.archaeologyexpert.co.uk/archaeologicaldating.html
When museums and collectors purchase archaeological items for their
collections they enter an expensive and potentially deceptive commercial
fine arts arena. Healthy profits are to be made from illicitly plundered
ancient sites or selling skillfully made forgeries. Archaeology dating
techniques can assure buyers that their item is not a fake by providing
scientific reassurance of the artefact's likely age.
Archaeological scientists have two primary ways of telling the age of
artefacts and the sites from which they came: relative dating and
absolute dating.
Relative Dating In Archaeology
Relative dating in archaeology presumes the age of an artefact in
relation and by comparison, to other objects found in its vicinity.
Limits to relative dating are that it cannot provide an accurate year or
a specific date of use.
The style of the artefact and its archaeology location stratigraphically
are required to arrive at a relative date. For example, if an artefact,
say an oil lamp, is found co-located on the same floor of a governor's
dwelling, and that floor can be dated in archaeology terms by reason of
the patterns employed in the mosaic, then it is assumed that in relation
to the floor that the lamp is of the same age.
Stratigraphy As A Dating Technique
The underlying principle of stratigraphic analysis in archaeology is
that of superposition. This term means that older artefacts are usually
found below younger items. When an archaeological site is excavated the
sides of the unexcavated baulk reveals layering of subsequent
settlements and activity. Stratigraphic excavation is the recording and
study of these different strata as they are removed from the area.
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Style Analysis As An Archaeology Dating Technique
The shape and style of an artefact changes through time although its
function may remain the same. The changing styles of pottery, glass,
stoneware, and metal objects provide archaeology analysts with known
progressive sequences. Once an artefact is compared to its known
development date then whenever that item reappears in the archaeological
record, of that or any other site, it can quickly be dated.
The Weakness of Relative Dating
The potential flaws in relative dating in archaeology are obvious.
Simply assuming that an artefact is older because it was found at a
lower depth in the record is only subjective science. There are many
instances of deep holes being dug for rubbish pits or to locate well
water that protrude into the record of older strata injecting more
modern material as they are filled in over time. Landslides and slips
can completely change the topography of an entire archaeology site
burying what was once on top by that which is much older, hence
reversing the strata layers.
Absolute Dating As An Archaeology Dating Technique
A more precise and accurate archaeology dating system is known as
absolute dating and can in most circumstances provide a calendar year to
the object.
Since 1950 there has been a transformation in the dating techniques of
archaeologists. Absolute dating is highly dependant on laboratory
analysis. There are a number of techniques that have come to archaeology
through the nuclear research efforts during WW2.
Radiocarbon Dating In Archaeology
Radiocarbon dating uses the biological assumption that all living things
absorb carbon, both ordinary carbon, C12, and radioactive carbon, C14,
into their living tissue. At the moment of death the C14 begins to decay
at a rate that scientists already know from other experiments.
The missing amount can then determine how long it took to be lost and
therefore date the object to a precise period. C14 Radiocarbon dating
can only be used on organic matter.
Uranium - Lead Dating As A Dating Technique In Archaeology
Lithic items cannot be dated by C14 radiocarbon methods but the same
principle can be used using radioactive uranium. Rocks, when formed by
volcanic reaction or other cataclysmic event, contain a minute quantity
of radioactive substance. From the day of the rock's creation this
radioactivity begins to deplete. Like C14, by measuring the loss, a
scientist can attribute an age according to known loss rates.
Luminescence Dating In Archaeology
Artefacts that are made from crystalline materials and uncovered in an
excavation can be dated using luminescence analysis. Crystalline
minerals when subjected to intense heat will burn with differing colours
of flame. Mostly used to date pottery in archaeology the method is very
effective but costly.
The greatest problem with dating an artefact from an archaeology site is
that nearly every absolute dating process requires the destruction of at
least a piece of the object in conducting the analysis. There are
relatively few dating laboratories and having an artefact dated can be
an expensive exercise especially if the artefact is not of great value
itself.
(this one is fascinating to me btw..)
http://www.archaeologyexpert.co.uk/IndustrialArchaeology.html
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