The Distribution of Calcined Bone at the Col. Paul Wentworth Site, Rollinsford, NH

Calcined bone is a unique artifact on archaeological sites due to its potential for indicating areas of domestic activity and cooking. Calcined bone is distinct from other types of bone found on archaeological sites, mostly recognized for its stark white color, because of a unique set of processes. 

When exposed to heat, bone undergoes several chronological stages of chemical and physical change: dehydration, degradation of organic material, degradation of inorganic material, and then finally calcification. The temperature of the fire at which the bone is burned is significant to the color of the bone; Unburnt bone is typically a cream-yellow color. At temperatures of 100-200 degrees Celsius, the bone reaches a brown color. At 300 degrees Celsius, bone reaches a black color, and a gray color by 450-600 degrees Celsius. It's not until bone is burned at over 700 degrees Celsius in which it calcifies— sometimes referred to as bone ash. 

Bone that has been burnt on archaeological sites may indicate a number of possibilities regarding the site's historic usage: food preparation, fuel, site clean-up and rubbish disposal, landscape fires, and other culture-specific practices. Presence of calcined bone on an archaeological sites compels a strong indication of cooking activity since such extreme prolonged temperatures are required for the process of calcification to occur. 

The sleeper feature outlined on the distribution map is made up of stains left behind in the subsoil by floorboard supports; evidence suggests that the calcined bone in the middle and north blocks may indicate the presence of historical outbuildings on the site aforementioned in my previous post. Specifically, calcined bone excavated from the sleeper feature would suggest historical cooking activity rather than deposited material as a result of twentieth-century activity of the site. 

The presence and deposition of calcined bone embedded in the soils relay important information on the purposes and functions of historic sites which have the potential to either strengthen or weaken the arguments for human living quarters.

Works Cited

McDowell, M. 

2023 "Landscape Fires and their impacts on Aboriginal cultural heritage places and artefacts in southeastern Australia." In Fires in Gunaikurnai Country: Landscape Fires and their Impacts on Aboriginal Cultural Heritage Places and Artefacts in Southeastern Australia, edited by Bruno David, Archaeopress.