A common assumption in Near Eastern tell archaeology is that the majority of sediments originate from degraded mud bricks. Little is known about the mechanism of mud brick wall degradation. Here we present a detailed macro- and microscopic ethnoarchaeological study of the degradation of a mud brick house and propose a comprehensive mechanism for tell formation processes in arid environments. The study took place in southern Israel by trenching a ca. 60 year old abandoned mud brick house, followed by extensive sediment sampling. Macroscopic observations showed that mud brick walls degrade by collapse of single bricks and/or collapse of intact wall parts, either inwards or outwards. In addition, infill sediments within the house and outside it, in close proximity to its walls, form alternating sedimentary layers of various colors and textures. The degraded mud brick material lost its distinctive macroscopic structure, which makes it impossible to accurately identify this material by field observations alone. Mineralogical and elemental analyses established the sources of the house infill sediments, namely mud bricks and wind blown sediments. Alternating layers mostly originate from mixing between degraded mud brick material and wind blown sediments. Micromorphological observations revealed microscopic mechanisms of mud brick degradation and include processes of mud slurry gravity flows, sediment coatings and infillings, wind abrasion of walls, small-scale puddling, and bioturbation. This study provides a working scheme for site formation of abandoned mud brick structures in arid environments. It provides a set of criteria by which it is possible to differentiate floors from post-abandonment sedimentary features and thus improves the reliability of activity area research.
Bibliographical noteFunding Information:
We are indebted to Dan Gazit without whom this project would not have been carried out as smoothly and successfully as it did. We would also like to thank our colleagues, especially Aren Maeir for contributing excavation equipment, Lior Regev for help with FTIR analyses and Steve Weiner for commenting on an earlier draft of this manuscript. We are also grateful to those who helped in the excavation: Noa Lavi, Efrat Bocher, Shira Gur-Arie, Dan Cabanes, Maite Cabanes and Tomer Aharon. The project was funded by a grant from the Israel Science Foundation (Bikura track, 527/09 ) to RSG and was assisted by funding from the Kuschitzky Fund at the Dept. of Land of Israel Studies and Archaeology ( Bar Ilan University ), the Kimmel Center for Archaeological Science at the Weizmann Institute and a European Research Council under the European Community’s Seventh Framework Programme ( FP7/2007-2013 )/ERC grant agreement no 229418 to Israel Finkelstein and Steve Weiner.
- Degradation processes
- Fourier-transform infrared (FTIR) spectroscopy
- Mud bricks
- Site formation processes
- X-ray Fluorescence (XRF)
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