Stone boiling is a moist-heat cooking method. It involves placing heated rocks into a water-filled container to heat the liquid to the point where it can be used to cook. This method of food preparation is a fuel-intensive process and it often requires the heating and reheating of stones before the water reaches an effective cooking temperature.
Indigenous peoples in what is now Canada and the United States of America, especially on the West and Northwest Coast, used stone boiling. Cooking this way allowed for a more controlled temperature which made the extraction of fats and oils easier while also allowing for more nutrients to be obtained from such oils. Indigenous peoples first use of stone boiling, based on archaeological excavations in the Northern Plains, was dated at 4800 years ago. However, its use became more prominent between 250 C.E. and 1750 C.E.; Brian Reeves, professor of anthropology and archaeology at the University of Calgary, argued this is because of the need to feed increasing populations.
Materials
Above-ground containers
Above-ground cooking vessels used in stone boiling consisted of: bark baskets and bark containers; pottery; as well as suspended animal paunches and hides. There are even instances of small canoes being utilized as cooking containers on the Northwest Coast for the preparation of whale fat.
Indigenous peoples’ usage of a given above-ground container type depended on the resources available to them. For example, First Nations on the Northwest Coast and eastern Canada are reported by Harold E. Driver, former professor of anthropology at Indiana University, and William Clifford Massey, former professor of anthropology at the University of Washington, to have used bark baskets and bark containers for stone boiling. However, bark baskets were preferred to bark containers because they did not burn as easily, which made them more durable. In eastern Canada among some Haudenosaunee peoples, large clay pots with thick walls were likely used for stone boiling. While such walls allowed for better insulation, Gregory Braun, professor of anthropology at the University of Toronto, attributed their thickness to the need to support the container’s structure without breaking, given the weight of the rocks inside. Plains peoples used suspended animal paunches in addition to below-ground boiling pits.
Below-ground containers
Plains peoples are reported by Jack W. Brink, curator of archaeology with the Royal Alberta Museum, and Bob Dawe, assistant curator of archaeology with the Royal Alberta Museum, to have used below-ground boiling pits because the wind cooled above-ground containers before the rocks could efficiently heat the water which made the already fuel-intensive process less effective and viable. At Head-Smashed-In Buffalo Jump in what is now Alberta, Canada, bison hides were used to line pits that held the water.
Stones
Indigenous peoples’ use of stone boiling involved heating stones in or near a hearth or fire before the rocks were transferred to a nearby water-filled container by using forked sticks. The rocks would then be removed from the container by using those forked sticks and bracing the stones to the side of the container.
Rocks used in stone boiling were often fist-sized. This is because the heat that smaller stones were capable of transferring was not worth the resources required to reach such a temperature. As such, once a stone became smaller than 10 cm in any dimension, it was discarded.
The reason stones would break is because of their repeated reheating, a process that could heat the rocks upwards of 500°C. At Head-Smashed-In Buffalo Jump, no complete boiling stones were found after eight seasons of excavation, which according to Jack W. Brink and Bob Dawe attests to the rocks being reused. The rocks in question are hypothesized by Brink and Mr. Dawe to have been imported from a nearby river, and were more predominant in stone boiling than the available sandstone because the river rocks would heat up more slowly and transfer their heat more slowly making it a better material for cooking.
