An ethnoarchaeological study of cooking installations in rural Uzbekistan: Development of a new method for identification of fuel sources

Mud constructed cooking installations such as ovens and hearths are common in modern, pre-modern and archaeological domestic contexts in West and Central Asia. Archaeological cooking installations are primarily identified using analogy of shape and size to ethnographic installations. The study presented here establishes direct evidence to the use of fire within mud constructed cooking installations, thus providing means for reducing ambiguity in identification of archaeological cooking installations. In addition, we present here a newly developed method that enables a clear-cut distinction between wood and dung ashes used as fuel materials in many modern and archaeological domestic contexts. The study is based on an ethnoarchaeological research in rural households at the Republic of Uzbekistan that was followed by geoarchaeological analyses of installation walls, wood ash, dung ash and wood and dung standards collected in the study area. Field work included ethnographic observations, interviews with informants and temperature measurements during cooking experiments. We show that changes in the clay mineral structure due to exposure to high temperatures on the interior walls of cooking installations can be detected using FTIR (Fourier Transform Infrared) spectroscopy, providing for the first time direct evidence to the use of fire within such installations. We demonstrate that the temperature recorded by clay alteration on installation walls as well as in the ashes left on installation bottoms does not correspond to baking or cooking temperatures. We also show that the newly developed method, based on the ratio of wood ash pseudomorphs to dung spherulites, separates between wood and dung ashes with very high certainty. Yet, we identify a range of values where differentiation between wood and dung ashes is uncertain, and suggest it results from intensive mixing processes. Lastly, we show that phytolith morphotype analysis is an insufficient tool, if used alone, for distinguishing wood from dung ashes in the study area. The newly developed tools for temperature estimation within mud constructed installations and for fuel origin determination contribute to better understanding of cooking-related practices, and can be applied to archaeological contexts worldwide.