Organic materials found in excavations may include horn and bone, wood and charcoal, seeds, shell and, rarely, hide or leather. Much organic material does not survive in the typical burial environment in the eastern United States which is marked with fluctuating wet and dry conditions and generally acidic soils. Sometimes atypical burial environments — saturated soils or extremely dry soils— lead to better organic preservation. When materials are recovered from such an unusual environment, it is essential to keep the artifact in a similar environment until conservation intervention can occur.
Sometimes, organic artifacts are very fragile and need to be reinforced with vacuum impregnation or careful overcoating with an inert, conservation friendly material such as butyl acroloid B-72 or roplex.
The lack of organic preservation means that we often only recover archaeologically a small sample of the overall material culture of a given human population. We need to read into the record the missing artifacts. It also means we are mandated to stabilize and preserve any organic materials
We are fortunate in St. Mary’s City that our cultural deposits often contain considerable oyster shell which serves to neutralize the natural soil acidity.