What do lines of demarcation illustrate in fire investigations?

Lines of demarcation are crucial in fire investigations as they visually represent the different effects that fire has on materials within the affected area. These lines help investigators understand how fire conditions, such as heat intensity and duration, have influenced various materials differently across a scene. For example, some materials may fully combust while others may exhibit only heat exposure, and these differences can be clearly illustrated with lines of demarcation.

By mapping out the varying levels of fire effects, investigators can draw conclusions about the fire’s spread, the intensity of the heat, and the proximity of materials to the fire source. This aids in establishing a cause and origin for the fire, enhances the understanding of fire dynamics within the structure, and supports accurate reporting and documentation of findings.

The other options do not capture the specific role of lines of demarcation effectively. While they may relate to aspects of a fire investigation, they do not focus on illustrating the variance in fire effects amongst materials, which is the essence of what lines of demarcation represent.