16th Century waste deposit at Burslem Market Place, 2001

Stratigraphy is the continual build-up of material layers (strata) one upon the other. The process of deposition means that the top layer is the most recently deposited (hence the youngest) whilst the bottom layer was the first to be deposited and is the oldest. Archaeologists strip these layers off in sequence starting with the most recent deposit at the top.

Pottery and coins are used to date other material found in the same layer. This sequence can then be used to create a relationship across the site and give information about how an area was used during a specific period. Groups of deposits can be put together to define phases of activity.

Some stratigraphy is easily identifiable - soil to wall – whilst others are not. These can include subtle changes in the soil colour, texture and composition (high / low levels of inclusions of mortar, charcoal, stones, etc).