Deric Yoakam
Archaeology 1030
April 24, 2012
Dykman
“Dating Types used in Archaeology”
Archaeologists are always interested in ways to improve methods used in dating
specimens in the archaeology world. There are numerous methods being used today as well as
improvements on old methods and even improvements on incorrect dating techniques from the
past. As archaeology improves on the types of methods used in dating it allows others to
accurately date specimens which may have been misdated or perhaps give it a more specific date.
Archaeologists use a variety of methods, depending on the circumstances of the piece, when
items are being dated. It has to be determined which test will be most effective in order to obtain
the correct date depending on the circumstances of the specimens. Luminescence dating has been
used over the past 30 years and seems to be a viable tool for archaeologists, and is becoming one
of the most efficient techniques in archaeological dating.
Luminescence dating refers to techniques using the emission of light from a material
which has been stimulated in some way. Using the intensity of the light determines the age of the
specimen being tested. The most common and best known technique is Thermoluminescence
dating, or (TL). Another type of luminescence dating is optically stimulated luminescence dating
(OSL) and it is gaining popularity by archaeologists as a useful dating technique. In the 1950’s
luminescence was used as a way to detect radiation exposure and led to the development of using
it for accurate dating, although it is commonly used in radiation exposure. It wasn’t until the
1960’s that a dating technique was discovered at Oxford University under Martin Aitken and in
Demark, under Vagn Mejdahl. There are over 50 dating laboratories throughout the world today,
with only a handful in America, and only one concerned with archaeological use. The earliest
use of dating with TL was used on pottery, yet the technique was neither easy nor cheap to
perform. This is one reason for the decline of using TL by archaeologists, it seemed more
expensive and technical than what the results yielded (Dykeman, Towner, Feathers.), (Feathers).
During the 1980’s TL dating was rarely being used and in its biggest declines of use,
other techniques using TL began to emerge, although expensive. Interest in dating other
materials began to arise and TL started being used to date materials such as: burned lithics,
particularly those beyond the radiocarbon table, but sediments became the biggest interest.
Sediment dating reflects the bigger challenge in obtaining dates where light is the zeroing
mechanism. The benefits of research on sediments should bring new relevance to dating
specimens in the archaeology world. Using luminescence dating has become a reliable dating
technique and could be considered the preferred dating method, depending on the specimen
being tested (Dykeman, Towner, Feathers.), (Feathers).
Luminescence dating helps archaeologists in receiving accurate dates, but in order to
obtain these dates archaeologists must consider three important steps. First, archaeologists must
define in unambiguous terms the event they are interested in dating. Dates can be obtained
without any clear understanding of what is actually being dated and how the dates could relate to
the overall bigger questions being addressed. Second, archaeologists must choose a method that
will provide the most accurate measurement of the target event. This requires archaeologists to
determine which method to use, among the many available, to obtain the most accurate date and
possibly more than one method could be used in gaining these results. Finally, a strategy needs to
be used in order to maximize precision, possibly by approaching the dating work from different
angles or by using different scales. When archaeologists have considered these three steps
luminescence dating provides three advantages when determining relative dates. The first, it
provides dates for materials that are common and abundant archaeologically, such as pottery,
ceramics, and other artifacts. Second, it covers an archaeologically important age range (from the
very recent to over 100,000 years) that few of the other methods and techniques can equal.
Finally, it directly dates archaeologically relevant events and it avoids the problem of association
that plagues other known techniques. Luminescence dating along with its strengths has its
weaknesses such as the complex variables that can be difficult to estimate in any situation.
Luminescence dating is reducing the disadvantages associated with its techniques and working
towards proving how its advantages can be further used in relative dating. (Feathers).
What makes the archaeology record interesting is the preservation, in the configuration of
various attributes, of past events relevant to the evolution of human culture. An event is the time
when such a configuration came into existence. Dating is the means by which these events are
ordered in time. Not all events are amenable to dating, however a distinction is made between
dating events, those events actually dated, and target events of archaeological interest. When the
two do not coincide or when they fail to bridge arguments, they are required to link the two
proving the two events are linked and took place in relation to each other. Bridging arguments
are generally made by “association” or locational proximity. The proof of historic relatedness
requires an understanding of the formation process that is usually only imperfectly understood.
The power of dating technique is governed by both its accuracy and its precision. Accuracy is
increased if the dating technique addresses the target event directly with minimal reliance on
bridging arguments and Luminescence dating is leading the way (Feathers).
Luminescence on specimens dates the last heating event (to about 450 degrees
Celsius).In most cases involving pottery or ceramics this corresponds with when it was made, or
at least the time it was last used. Lithics receives its dates from the last heating (if heated at all)
corresponds with the manufacturing, or when accidental firing occurred during the course of use,
discounting post depositional firing. Preservation has made pottery and lithics by association
with other organics, a practice which is much less secure and with unknowable accuracy. Diverse
origins of associated carbon, problems of old wood in arid climates, and contamination from
geologic carbon are all problems in chronological studies. Archaeologists continue to make
improvements on the many different dating techniques and using the most efficient one or two
for dating is continually improving the accuracy of dating artifacts. In doing so it not only give
an accurate date, it also allows archaeologist to be able to create a bridge and determine how the
artifact was used in the everyday lives of different cultures (Feathers).
There are occurring problems when trying to acquire a date in the archaeology world
such as radiography and high-energy light exposure and how further testing is useless. With the
improvements and developments of optical and neutron lasers, we will doubtless see these highenergy radiators supplied to both physical and archaeological anthropology. X-Ray radiography
will certainly be expanded now that portable units are being developed, allowing examination of
the interiors of encrusted artifacts, permitting the examination of baulks, profiles, survey cores,
and structural features of buildings in the archaeological field. The study of design and structural
aspects of ceramic and other artifacts have long been feasible although relatively infrequent.
There can be no denying the importance of the methods used to get at information buried within
objects and otherwise inaccessible without destroying the object under study, the radiation
exposure entailed in their kind of research threatens to make other kinds of analyses impossible
(Rowlett).
While heavy radiation is generally considered nondestructive in that there is no change in
the physical appearance of the specimen, it nonetheless produces modification at the molecular
and atomic levels. While the appearance of the specimen may not change, it is contaminated for
other kinds of radiometric tests, not only radiocarbon dating, but more important
thermoluminescence analysis and related techniques for measuring accumulated radiation
exposure in the ground. The intense light energy put out by the optical laser may also affect the
trapping of electrons measured by thermoluminescence. Not only does thermoluminescence
dating extended the range beyond carbon-14, but since the radiation damage which produces
thermoluminescence increases through time, the older a specimen is, the more there is to
measure. While mineralized fossil bone cannot be absolutely dated to the time of its life, the age
of mineralization gives archaeologists a respectable date. Research is under way to make a
somewhat similar analysis, but involving only negligible heating, of these materials. The low
heat levels eliminate some of the problems of dating bone (Rowlett).
The important thing is that methods within the archaeology field are improving daily and
with new developments on techniques and improvements on machines dating is becoming more
accurate as time moves forward. Although there may be many types of methods used in dating
and careful application depending on the specimen and its environment, allows archaeologists a
viable tool for recording dates not only on present artifacts, but also on past artifacts. The
importance of thermoluminescence dating is proving to be very helpful to archaeologists and
their methods on dating objects in the archaeological field within the past 30 years. With such
improvements on dating it has allowed more accurate dates enabling bridges into human
behavior and life. Although there may never be one ideal dating technique for archaeologist, the
fact that Thermoluminescence dating is becoming one of the fastest growing methods gives
archaeologists the opportunity to continuing the goal of acquiring the accurate dates using the
best methods for the object being dated. Despite the cost America needs to understand the
importance of Thermoluminescence dating and consider building facilities to handle such tests.
If it would help archaeologists understand events in the past and improves archaeology dating
then why not consider it.
Works Cited
Feathers, James. "The Application of Luminescence Dating in American Archaeology." Journal
of Archaeological Method and Theory. 4. no. 1 (1997): 1-66.
Dykeman, Douglas, Ronald Towner, and James Feathers. "Correspondence in Tree-Ring and
Thermoluminescence Dating." American Antiquity. 67. no. 1 (2002): 145-164.
Rowlett , Ralph. "Hazarda of Radiography and High-Energy Light Exposure for
Thermoluminescence Analysis." Current Anthropology. 16. no. 2 (1975): 263.