The excavation starts with the installation of the site huts then the removal of the topsoil covering the excavation area.

The topsoil is taken off so as to reach the archaeological layers. Each archaeological layer corresponds to a moment in the history of the site. Its limits are determined by archaeologists, sometimes helped by geologists, who study its colours, textures as well as the structures that it may contain. The layers are an essential guide for the archaeologist.

During the excavation the stratification (the succeeding layers which correspond to a particular moment in the history of the site) is of paramount importance. Usually the oldest layers are covered by the more recent ones. But sometimes the deposits have been damaged or removed and only the bases of deep pits, for example, remain. The finds inside, if there are any, give an indication about the date of the structure.

As the excavation unfolds, the drawing of sections and plans is an essential part of preservation by record. The archaeologist can also call upon the services of a topographer* who, using a theodolite, takes precise measurements guaranteeing the preparation of an accurate site plan.

Archaeological finds*, when unearthed, are marked with the details of where they were found (site, zone and layer or structure number) before being transferred to the finds area for treatment. In some cases, they have to be consolidated on site before removal.
In fact, data recorded about archaeological deposits (stratigraphic position, drawings* and photographs in situ) are very often more important than the objects discovered.