Forensic archaeology is the application of archaeology (the study of past cultures and activities) to legal investigations. The skills and methods used by archaeologists to find and interpret buried or hidden sites of past activity have direct application to modern forensic investigations.
The Forensic Archaeologist combines knowledge of osteology and human remains with archaeological techniques to help recover finds and provide vital evidence for the investigative team. With osteology background, the Forensic Archaeologist can provide field guidance on the age, sex, and other physical characteristics of the remains, while as an experienced excavator, the Forensic Archaeologist examines the scene so that artifacts will be accurately located and recovered.
When a body is buried, there are several changes that occur to an area that can generally be detected by the forensic archaeologist. One of these is the change of soil compaction: Soil is made up of organic and mineral components that form through natural processes. Soil typically forms over very long periods. People affect the natural soil when, for instance, they plough it to plant crops, or cut into it to construct buildings. When people interrupt naturally formed soil, they change how solid it is (its compaction). The same principle applies when a person digs a grave to bury a body. Loose, less compact soil suggests that it has been recently disturbed, typically by human or animal activity. Sometimes contrasts in soil compaction can be seen but archaeologists using tools such as a shovel or trowel can usually feel the difference in soil compaction, which tells them where the naturally formed soil has been disturbed.
Soil compaction changes with the size of the soil grain. Sand grains are larger than silt grains, which are in turn larger than grains of clay. Soil compaction can naturally differ greatly from one area to another, but recent clandestine or unmarked graves show soil looser than the naturally formed soil that surrounds them. The same principles apply for more ancient archaeological features and activity, but over time the compaction of the disturbed soil generally appears more like the undisturbed soil around it.