Methods for estimating a realistic date for an event or object
Chronological dating
, or simply
dating
, is the process of attributing to an object or event a date in the past, allowing such object or event to be located in a previously established
chronology
. This usually requires what is commonly known as a "dating method". Several dating methods exist, depending on different criteria and techniques, and some very well known examples of disciplines using such techniques are, for example,
history
,
archaeology
,
geology
,
paleontology
,
astronomy
and even
forensic science
, since in the latter it is sometimes necessary to investigate the moment in the past during which the death of a
cadaver
occurred. These methods are typically identified as absolute, which involves a specified date or date range, or relative, which refers to dating which places artifacts or events on a timeline relative to other events and/or artifacts.
[1]
Other markers can help place an artifact or event in a chronology, such as nearby writings and stratigraphic markers.
Absolute and relative dating
[
edit
]
Dating methods are most commonly classified following two criteria:
relative dating
and
absolute dating
.
Relative dating
[
edit
]
Relative dating
methods are unable to determine the absolute age of an object or event, but can determine the impossibility of a particular event happening before or after another event of which the absolute date is well known. In this relative dating method,
Latin
terms
ante quem
and
post quem
are usually used to indicate both the most recent and the oldest possible moments when an event occurred or an artifact was left in a
stratum
, respectively. But this method is also useful in many other disciplines. Historians, for example, know that Shakespeare's play
Henry V
was not written before 1587 because Shakespeare's primary source for writing his play was the second edition of
Raphael Holinshed
's
Chronicles
, not published until 1587.
[2]
Thus, 1587 is the
post quem
dating of Shakespeare's play
Henry V
. That means that the play was without fail written after (in Latin,
post
) 1587.
The same inductive mechanism is applied in archaeology, geology and paleontology, by many ways. For example, in a stratum presenting difficulties or ambiguities to absolute dating,
paleopalynology
can be used as a relative referent by means of the study of the pollens found in the stratum. This is admitted because of the simple reason that some botanical species, whether extinct or not, are well known as belonging to a determined position in the scale of time.
For a non-exhaustive list of relative dating methods and relative dating applications used in geology, paleontology or archaeology, see the following:
- Paleopalynology
, also spelt "Palaeopalynology", the study of fossilized pollens for the relative dating of geological strata.
Absolute dating
[
edit
]
Absolute dating
methods seek to establish a specific time during which an object originated or an event took place. While the results of these techniques are largely accepted within the scientific community, there are several factors which can hinder the discovery of accurate absolute dating, including sampling errors and geological disruptions.
[5]
This type of chronological dating utilizes absolute referent criteria, mainly the
radiometric dating
methods.
[6]
Material remains can be absolutely dated by studying the organic materials which construct the remains. For example, remains that have pieces of brick can undergo the process of
thermoluminescence (TL)
dating in order to determine approximately how many years ago the material was fired.
[7]
This technique was used to discover the date of St. James Church in Toru? by testing the thermoluminescence of removed bricks. In this example, an absolute date was determined which filled a gap in the historical knowledge of the church.
[8]
These techniques are utilized in many other fields as well. Geologists, for example, apply absolute dating methods to rock sediment in order to discover their period of origin.
[9]
Some examples of both radiometric and non-radiometric absolute dating methods are the following:
- Carbon dating
: Reveals the age of artifact, which is used to establish the chronology of the culture. The oldest dates that can be reliably measured by this process date to approximately 50,000 years ago.
- Cementochronology
, this method does not determine a precise moment in a scale of time but the age at death of a dead individual.
Dating methods in archaeology
[
edit
]
Just like
geologists
or
paleontologists
,
archaeologists
are also brought to determine the age of both ancient and recent humans. Thus, to be considered as archaeological, the remains, objects or artifacts to be dated must be related to human activity. It is commonly assumed that if the remains or elements to be dated are older than the human species, the disciplines which study them are sciences such geology or paleontology, among some others.
Nevertheless, the range of time within archaeological dating can be enormous compared to the average lifespan of a singular human being. As an example
Pinnacle Point
's caves, in the southern coast of
South Africa
, provided evidence that marine resources (shellfish) have been regularly exploited by humans as of 170,000 years ago.
[16]
On the other hand, remains as recent as a hundred years old can also be the target of archaeological dating methods. It was the case of an 18th-century
sloop
whose
excavation
was led in
South Carolina
(
United States
) in 1992.
[17]
Thus, from the oldest to the youngest, all
archaeological sites
are likely to be dated by an appropriate method.
Dating material drawn from the
archaeological record
can be made by a direct study of an
artifact
, or may be deduced by
association
with materials found in the
context
the item is drawn from or inferred by its point of discovery in the
sequence
relative to datable contexts. Dating is carried out mainly
post excavation
, but to support good practice, some preliminary dating work called "spot dating" is usually run in tandem with
excavation
. Dating is very important in archaeology for constructing models of the past, as it relies on the integrity of dateable objects and samples. Many disciplines of
archaeological science
are concerned with dating evidence, but in practice several different dating techniques must be applied in some circumstances, thus dating evidence for much of an archaeological sequence recorded during excavation requires matching information from known absolute or some associated steps, with a careful study of
stratigraphic relationships
.
In addition, because of its particular relation with past human presence or past human activity, archaeology uses almost all the dating methods that it shares with the other sciences, but with some particular variations, like the following:
Written markers
[
edit
]
- Epigraphy
? analysis of inscriptions, via identifying graphemes, clarifying their meanings, classifying their uses according to dates and cultural contexts, and drawing conclusions about the writing and the writers.
- Numismatics
? many coins have the date of their production written on them or their use is specified in the historical record.
- Palaeography
? the study of ancient writing, including the practice of deciphering, reading, and dating historical manuscripts.
Seriation
[
edit
]
Seriation
is a relative dating method (see, above, the list of relative dating methods). An example of a practical application of seriation, is the comparison of the known
style
of artifacts such as
stone tools
or pottery.
Age-equivalent stratigraphic markers
[
edit
]
Stratigraphic relationships
[
edit
]
The
stratigraphy
of an archaeological site can be used to date, or refine the date, of particular activities ("contexts") on that site. For example, if a context is sealed between two other contexts of known date, it can be inferred that the middle context must date to between those dates.
See also
[
edit
]
References
[
edit
]
- ^
"Archaeological Dating"
.
Crow Canyon Archaeological Center
. Retrieved
2020-07-31
.
- ^
Greer, Clayton A. (June 1954). "Shakespeare's Use of The Famous Victories of Henry V".
Notes and Queries
.
199
: 238?41.
doi
:
10.1093/nq/199.jun.238
.
- ^
Chemistry Professor Shimon Reich, a specialist in
superconductivity
, has demonstrated a method for dating artifacts based on the magnetic properties of
lead
, a material widely used in Israel and elsewhere in antiquity. Reich and coworkers found that at cryogenic temperatures, lead becomes a superconductor, but the corrosion products formed from centuries of exposure to air and water (
lead oxide
and
lead carbonate
) do not superconduct. On the basis of magnetic measurements and comparison with artifacts that were known (using other techniques) to be up to 2500 years old, the group showed that the mass of lead corrosion products is directly proportional to an object's age (New Journal of Physics, 2003, 5, 99)
- ^
Jacoby, M. (5 March 2007).
"Chemistry in the Holy Land"
.
Chemical & Engineering News
. American Chemical Society. p. 20.
- ^
Watchman, Alan; Twidale, Charles (2002-07-01).
"Relative and 'absolute' dating of land surfaces"
.
Earth-Science Reviews
.
58
(1): 1?49.
doi
:
10.1016/S0012-8252(01)00080-0
.
ISSN
0012-8252
.
- ^
IUPAC
,
Compendium of Chemical Terminology
, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "
radioactive dating
".
doi
:
10.1351/goldbook.R05082
- ^
Sanjurjo-Sanchez, Jorge (2016).
An Overview of the Use of Absolute Dating Techniques in Ancient Construction Materials
. Multidisciplinary Digital Publishing Institute.
OCLC
1029510083
.
- ^
Chru?ci?ska, Alicja; Cicha, Anna; Kijek, Natalia; Palczewski, Piotr; Przegi?tka, Krzysztof; Sulkowska-Tuszy?ska, Krystyna (2014-12-01).
"Luminescence dating of bricks from the gothic Saint James Church in Toru?"
.
Geochronometria
.
41
(4): 352?360.
doi
:
10.2478/s13386-013-0165-y
.
ISSN
1897-1695
.
- ^
McBeth, Joyce; Panchuk, Karla; Prokopiuk, Tim; Hauber, Lyndsay; Lacey, Sean (2020-01-08),
"Overview of Relative and Absolute Dating"
,
Introductory Physical Geology Laboratory Manual ? First Canadian Edition (v.3 - Jan 2020)
, retrieved
2020-07-31
- ^
J L Bada (1985). "Amino Acid Racemization Dating of Fossil Bones".
Annual Review of Earth and Planetary Sciences
.
13
: 241?268.
Bibcode
:
1985AREPS..13..241B
.
doi
:
10.1146/annurev.ea.13.050185.001325
.
- ^
Laureano Canoira; Maria-Jess Garca-Martnez; Juan F. Llamas; Jos E. Ortz; Trinidad De Torres (2003).
"Kinetics of amino acid racemization (epimerization) in the dentine of fossil and modern bear teeth"
.
International Journal of Chemical Kinetics
.
35
(11): 576?591.
doi
:
10.1002/kin.10153
.
- ^
B. J. Johnson; G. H. Miller (1997). "Archaeological Applications Of Amino Acid Racemization".
Archaeometry
.
39
(2): 265?287.
doi
:
10.1111/j.1475-4754.1997.tb00806.x
.
- ^
"Quantifying Time-Averaging In 4th-Order Depositional Sequences: Radiocarbon-Calibrated Amino-Acid Racemization Dating of Late Quaternary Mollusk Shells from Po Plain, Italy"
. 2008. Archived from
the original
on 2015-01-22
. Retrieved
2016-08-18
.
The results provide a compelling case for applicability of amino acid racemization methods as a tool for evaluating changes in depositional dynamics, sedimentation rates, time-averaging, temporal resolution of the fossil record, and taphonomic overprints across sequence stratigraphic cycles.
- ^
Eighmy, Jeffery; Sternberg, Robert, eds. (1990).
Archaeomagnetic Dating
. Tucson: The University of Arizona Press.
ISBN
9780816511327
.
- ^
"Fire And Water Reveal New Archaeological Dating Method"
.
Science Daily
. May 25, 2009
. Retrieved
2009-05-26
.
A team from the
University of Manchester
and the
University of Edinburgh
has discovered a new technique which they call 'rehydroxylation dating' that can be used on
fired clay
ceramics like bricks, tile and pottery.
- ^
Marean, Curtis W.; Bar-Matthews, Miryam; Bernatchez, Jocelyn; Fisher, Erich; Goldberg, Paul; Herries, Andy I. R.; Jacobs, Zenobia; Jerardino, Antonieta; Karkanas, Panagiotis; Minichillo, Tom; Nilssen, Peter J. (Oct 18, 2007).
"Early human use of marine resources and pigment in South Africa during the Middle Pleistocene"
(PDF)
.
Nature
.
449
(7164): 905?908.
Bibcode
:
2007Natur.449..905M
.
doi
:
10.1038/nature06204
.
ISSN
0028-0836
.
PMID
17943129
.
S2CID
4387442
.
- ^
"
Clydesdale Plantation 18th-Century Sloop Excavation
",
Institute of Nautical Archaeology
, Texas, USA
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