"Lined hearths are easily identified by the presence of fire-cracked rock, often created when the heat from the fires inside the hearths chemically altered and cracked the stone. Often present are fragmented fish and animal bones, carbonized shell, charcoal, ash, and other waste products, all imbedded in a matrix of soil that has been deposited atop the hearth. Unlined hearths, which are less easily identified, may also include these materials. Because of the organic nature of most of these items, they can be used to pinpoint the date the hearth was last used via the process of radiocarbon dating. Although carbon dates can be negatively affected if the prehistoric users of the hearth burned old wood or coal, the process is typically quite reliable."
(burn burn burn...)
(burn burn burn...)