n the same way, external and internal factors, at the time of the trees existence, can also cause problems and anomalies. The external factors, such as temperature, light, carbon dioxide and oxygen can also affect the inside of the tree by altering the nature of enzymes and the like. As a result of both factors, it is conceivable that, under good conditions one year, no rings may grow. In another, less positive year, two rings might appear. Clearly such factors will compromise the integrity of any conclusions we might draw from the samples. Indeed, due to ring growth being variable, there are some species of tree which are entirely unsuitable for dendrochronology. Some such species are Cupressus Arzonia and some types of Juniperus. Likewise, some areas of the world are generally unsuitable for this process, particularly the tropics, as species there do not bear distinctive seasonal patterns. Where the right type of wood is found, it must be well preserved enough so that the pattern may be read. Of course, the process is limited also by the fact that trees do not last forever. bristlecone pines can live in some cases up to 9000 years, yet this is unusual. Kuniholm writes:“As we try to push our matching of archaeological specimens beyond the range for which we have good control data, our confidence in the derived dates diminishes.”It is also important to realise that to study ancient peoples in this way, the buildings they constructed had to have been made using wooden timbers, yet this only began 4000 – 5000 years ago.Although there are clearly limitations to dendrochronology, it is apparent that in the right environment, and under correct conditions the process is reliable. It works best however when combined with other techniques, as I mentioned, such as radiocarbon dating. Obviously, the more analytical techniques there are applied to a sample, the greater the accuracy of the results will be. Although this is the cas...
