Excavation involves the controlled exposure of archaeological remains and their subsequent investigation and recording. There are two main types of circumstance under which modern archaeological excavation occurs:
The area under excavation is known as a trench. The soil within the trench is either excavated by systematically removing archaeological layers defined by their colour or texture or evenly in arbitrary levels. A range of human activities are revealed as features within these layers or levels, distinguished by physical remains or by variations in soil colour or texture. The fill of individual features may be sieved to collect small artefacts and ecofacts. All features as well as artefacts and ecofacts are carefully mapped and recorded. Artefacts, ecofact and samples are further analysed and recorded at the post—excavation stage.
The concept of ‘stratigraphy’ is vital to archaeological excavation and is based on the basic principle that the oldest archaeological deposits or layers will be at the bottom of the excavation. Understanding how different layers and features relate to each other, the ‘stratigraphic relationship’ enables the archaeologist to understand the sequence of activity on the site.
A ‘watching brief’ refers to the systematic observation and/or examination of non-archaeological excavation in order to identify and record archaeological deposits. It is not a precise method as it is usually virtually impossible to identify accurately the nature of archaeological features in industrial trenches and is usually carried out in areas with a less potential for important archaeological remains. A watching brief may also be used to monitor situations where preservation of archaeological remains is to be achieved in situ through foundation design. A watching brief may result in further archaeological work.