Summary
An interpretation of the features surrounding the complex and deliberate closure ritual in several collective Middle Neolithic tombs of the Ambrona Valley (Soria) is offered, where fire and quicklime played a major role in the rituals. The problems involved in the excavation and the understanding of this complex burial evidence are examined. The roles they might have played in the context of the important social and economic transformations of the local Neolithic groups around the end of the fourth millennium cal BC are also analysed. It is argued that the burial rituals tried to reinforce group solidarity at a time when the community was beginning to fragment, as the economic systems began to yield a surplus production whose management would have altered political structures.