THE USE OF STEM IN ARCHAEOLOGY Siying (Amy) Liu (LVI

The first known instance of archaeological excavation took place in the sixth century BCE when Nabonidus, the king of Babylon, excavated and tried to date a temple floor that was already over a thousand years old.

1 Ground penetrating radar in use near Stillwater, Oklahoma, USA in 2010

2 GPR depth section profile

3 Measuring 14C is now most commonly done with an accelerator mass spectrometer The fifth century BCE Greek historian Herodotus systematically collected old artefacts and sent them to support his view of history. By the medieval period, Europeans began digging up and keeping ancient, buried pots that had partially emerged due to soil erosion, and weapons that had turned up on farmland. More deliberate archaeology occurred more recently, when antiquarians, as they were known, excavated burial mounds in North America and North-West Europe, and this led eventually to the more meticulous and methodical archaeological excavation style that took over around the early- to mid-nineteenth century and is still being perfected today [1].

During our recent history of excavation, scientific techniques have played a key role in improving the efficiency and accuracy of the process and the results obtained. As excavation methods evolved with time, the development of technology made the excavating process both safer and more accurate. Modern archaeological excavation often involves auguring – the process of drilling many boreholes or cores across a site – as well as using remote sensing such as ground-penetrating radar before any actual excavating starts. With GPR (ground-penetrating radar), the radar signal (an electromagnetic pulse) is directed into the ground, which is then reflected by subsurface objects and layering that will be picked up by a receiver; the travel time of the reflected signal indicates the depth of each layer [2].

During the actual onsite process, stratigraphic excavation is used to remove phases of the site one layer at a time to keep the timeline of the material. Archaeologists can then determine the time period the artefacts are from through using the Law of Superposition, which indicates that layers of sediment further down will contain older artefacts than layers above; they also use the context of the discovery, information about the physical location where an artefact or feature was found as well as what it is located nearby. Specific dating methods can then be used for more accurate results: absolute dating enables the numeric age to be decided, and relative dating establishes the artefacts’ relationships to other elements. The most important method of absolute dating is radiocarbon dating.

Developed during the 1940s at the University of Chicago, this method is used to determine the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon. Through measuring the amount of 14C in a sample from any organic matter (e.g. a piece of wood or a fragment of bone) [3], calculations can be made to find a numeric age. The older a sample is, the less radiocarbon can be detected, the less 14C there is to be detected; and because the half-life of radiocarbon is about 5,730 years, the oldest dates that can be measured would thus date to approximately 50,000 years ago. For this remarkable work, the researcher Willard Libby received the Nobel Prize in Chemistry in 1960.

After excavation, digital methods are used to record the process and its results, which is crucial as archaeological excavation is an unrepeatable process. To achieve this, highly accurate and precise digital methods are often used by field archaeologists, with some of the examples being GPS, digital cameras and 3D laser scanners. After high quality digital data have been recorded, these data can then be shared over the internet for open access and use by the public and other archaeological researchers.

Although some criticise archaeological excavation to be unethical as it always faces the risk of damaging the artefacts without being able to repair them, it is undeniable that the advance in scientific discovery and improved technology have helped make the process more efficient and secure. As researchers continue exploring the incorporation of STEM into archaeology, it can be possible that the excavation and preservation of the relics will become even easier and more acceptable to the public.