Vitrified cattle dung in the Iron Age of southern Africa

Cattle were the basis of the most important social institutions in pre-colonial southern Africa, and so archaeologists have been interested in identifying cattle enclosures in Iron Age settlements. Occasionally, but of note, these byres are vitrified. Archaeologists usually explain this vitrification in terms of natural causes, such as internal combustion, lightning strikes and veld fires. Our present study in the Limpopo Valley, in conjunction with previous research, eliminates internal combustion because the greatest vitrification occurred in the open around the wooden fence. Higher levels of K2O and CaO in vitrified samples, determined by standard XRF analyses, support this conclusion. Moreover, spatial locations eliminate lightning as a likely cause, and the uneven distribution of vitrified dung through time, as well as the practical difficulty in burning abandoned pens, makes veld fires equally unlikely. Ethnographic information, on the other hand, indicates that villagers intentionally set the dung alight for hygienic and ideological reasons when their animals died unexpectedly.