How Archaeologists Work: Methods and Techniques

01

Survey and site identification

Before any excavation takes place, archaeologists usually carry out survey work to identify where sites might exist. This can involve walking across a landscape and recording visible surface finds, studying historical maps and documents, and examining aerial or satellite imagery for traces of past human activity, such as field boundaries or settlement mounds. In some cases, geophysical techniques such as ground-penetrating radar or magnetometry are used to detect buried features without disturbing the soil, allowing archaeologists to plan excavation more precisely and sometimes to avoid unnecessary digging altogether.

02

Excavation

When excavation does take place, it is normally carried out in carefully defined units, with soil removed in thin, controlled layers that follow the natural or cultural stratigraphy of the site. Stratigraphy, the sequence of layers built up over time, is one of the most important sources of relative dating evidence, since deeper layers are generally older than those above them, barring disturbance. Every find is recorded with its precise location, and samples of soil, charcoal, bone and other material are regularly collected for later laboratory analysis. Photography, scale drawings and, increasingly, three-dimensional digital recording are used to document the excavation as it proceeds.

03

Dating methods

Establishing when events occurred is central to archaeological interpretation, and several dating techniques are commonly used.

• Radiocarbon dating measures the decay of a radioactive carbon isotope in organic material such as charcoal, bone or shell, and is effective for material up to roughly fifty thousand years old.
• Luminescence dating estimates how long ago sediment or burnt material was last exposed to light or heat, which is particularly useful for sites beyond the range of radiocarbon dating.
• Relative dating methods, including stratigraphy and the comparison of artefact styles, allow archaeologists to establish sequences of events even when absolute dates are not available.
• Uranium-series dating is often applied to cave deposits such as flowstone, and can help date associated fossil or artefact-bearing layers in cave sites.

04

Laboratory analysis

Once material leaves the field, specialists examine it using a range of analytical techniques. Zooarchaeologists study animal bones to identify species, estimate age at death and look for evidence of butchery or cooking. Archaeobotanists examine preserved seeds, pollen and plant fragments to reconstruct past diets and environments. Residue and use-wear analysis can reveal how stone or bone tools were used, by studying microscopic traces and chemical residues left on their surfaces. In recent decades, ancient DNA analysis and isotope studies of bone and teeth have added further detail, allowing researchers to investigate diet, mobility and biological relationships among past populations.

05

Interpretation and publication

The final stage of archaeological work involves bringing together field records and laboratory results to build an interpretation of what happened at a site and why it matters. This interpretation is normally shared through academic publication, museum displays or public reports, so that other researchers can evaluate the evidence and build on it. Because archaeological interpretation often develops over time as new techniques and comparative data become available, published conclusions are regularly revisited and sometimes revised as the discipline progresses.

Responsible archaeological practice also involves conservation of finds and sites, and increasingly includes consultation with descendant or local communities, whose knowledge and interests are relevant to how sites are studied, presented and protected for the future.