by Jean Cascardi – Senior Field Archaeologist
Many folks know that archaeologists excavate test units using scientific methods. One of these methods is following vertical soil layers across a site; we refer to these layers as strata. Stratigraphic layers can be deposited by natural or cultural events, for example a flood event or the backfilling of an old, unused cellar. Both of these events help archaeologists to determine the time period and length of time a site was being used or occupied.
How many different soil colors do you see in this photo documenting Feature 92? During excavation an archaeologist will remove all of the soil colors separately. Other markers of soil layers changing, besides color, can be the texture or contents such as ash, rock, or charcoal. Many aspects of soil may provide insight into changes in land usage. The artifacts from each layer can then be carefully studied in the lab to determine the age of the soil layer or strata.