Potentials and limitations for the identification of outdoor dung plasters in humid tropical environment: a geo-ethnoarchaeological case study from South India

Shira Gur-Arieh,David E Friesem,Marco Madella,Noa Lavi

doi:10.1007/s12520-018-0682-y

Abstract

Dung has been an important material used by humans since at least the early Neolithic Period. It accumulated within domesticated animal enclosures and it was used as fuel and fertiliser as well as construction material. While the formers were studied in details, to date, the use of dung as a construction material received less attention. Here, we present a geo-ethnoarchaeological pilot study aimed at understanding the archaeological formation processes of outdoor dung-plastered floors and the possibility to identify dung markers. We studied two house terrace in a rural village from a humid tropical environment in South India (Western Ghats). Sediment samples were collected from the plastered terrace surfaces, the terraces embankment and from forest soil controls. Multi-proxy analysis of the samples included infrared spectroscopy, phytolith and dung spherulite quantification, loss on ignition, elemental analysis and micromorphological analysis. The plastering of the floors was made by mixing a quantity of dung with water and by spreading the slurry unevenly across the terrace. This result in formation of a 0.1- to 0.5-mm-thick dung crust that the analyses showed to be rich in humified organics but with very low concentrations of phytoliths and dung spherulites. The careless spreading of the dung slurry, however, resulted in localised deposition of dung lumps that displayed relatively high concentrations of phytoliths, dung spherulites, organic matter, phosphorus and strontium. The generally low preservation of dung markers seems to be related to pre- and post-depositional processes. Forest arboreal plants are low phytoliths producer, having therefore little input of these siliceous bodies in the animal faeces. Post depositional processes included trampling, sweeping and water runoff that caused severe mechanical weathering, resulting in the heavy decay of the dung crust and the removal of dung residues from the terrace surfaces. In addition, the acidic conditions of a humid tropical environment likely promoted the complete dissolution of dung spherulites. This study provides new data and insights on the potentials and limitations of dung identification in outdoor settings in humid tropical environments. We suggest possible directions for advancing the study of archaeological dung used as construction materials.

Highlights

The remains of dung found in archaeological sites bear important information regarding human-animal relations, animal domestication, human-environment interaction, paleoenvironmental reconstruction, subsistence practices and economy among other things
A control sample for dung was collected from a dung lump left on the terrace surface as a result of the heterogeneous nature of the dung slurry
Our aim was to test if the amount of phytoliths coupled with spherulites, elemental composition and micromorphology of floor sediments can be used as markers for outdoor dung-plastered surfaces under humid tropical environments

Summary

Introduction

The remains of dung found in archaeological sites bear important information regarding human-animal relations, animal domestication, human-environment interaction, paleoenvironmental reconstruction, subsistence practices and economy among other things. The use of dung marks a technological development and broader exploitation of resources derived from animals. It can be used as fertiliser (McCann 1997; Bogaard et al 2013; Gur-Arieh et al 2013), as fuel (Anderson and Ertug-Yaras 1998; Milek 2012; Portillo et al 2012, 2014, 2017; Gur-Arieh et al 2013, 2014; Spengler III et al 2013, 2014a, b, 2016; Spengler III and Willcox 2013; Doumani et al 2015) and as construction material (Mbae 1990; Reddy 1998; Boivin 2000; Matthews 2005, 2010; Karkanas 2006; Macphail et al 2007; Viklund et al 2013; Portillo et al 2014; Berna 2017). From the Neolithic period onwards, the use of dung became more common, in arid environments where wood is scarce (Kramer 1982)

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