The taphonomy and preservation of wood and dung ashes found in archaeological cooking installations: case studies from Iron Age Israel

Abstract

Cooking installations are among the most abundant features in Bronze and Iron Age archaeological sites in the southern Levant, yet until now their study has been mostly descriptive. We present a study of 11 purported archaeological cooking installations from three different Bronze and Iron Age sites in Israel in which we deployed a variety of microarchaeological techniques. We provide direct physical evidence, based on Fourier Transform Infrared (FTIR) spectroscopy demonstrating that the archaeological installations were operated with temperatures as high as 900 °C. Using this technique we also demonstrate that all the mud-constructed installations studied by us were internally-fueled and therefore should be identified as Tannurs rather than the externally- fueled Tabuns. We studied in detail the quantities of ash-related microscopic remains, including opaline phytoliths, calcitic wood ash pseudomorphs and dung spherulites. We show that phytolith morphotype analysis cannot distinguish between wood-dominated and dung-dominated fuel materials, while a newly developed method that calculates the ratio of ash pseudomorphs to dung spherulites (PSR method) makes such a distinction possible. Moreover, we experimented with the effect of partial dissolution on fuel ash PSR values and utilize the results to explain taphonomy and diagenesis associated with two types of archaeological cooking installations – pebble hearths and baking ovens. In addition, we identified micromorphological criteria that can be used to assess whether ash deposits in or above a cooking installations are in situ and/or disturbed. Taken together, all lines of evidence used in this study indicate that wood was the major fuel material across time and space in the studied archaeological contexts, while dung was a secondary source of fuel. This observation also cross-cuts different culture-historical entities (Philistines, Canaanites, Israelites and Egyptians). In addition, wood was preferred as fuel irrespective of environmental differences among the studied sites. This study is yet another demonstration of the value of integrating microarchaeological techniques and approaches to traditional macroscopic archaeology.