Atlas of Local Plants Species from the Kasitu Valley and their Ashes in thin section (in progress)

My research focuses on rockshelter sites in northern Malawi, specifically in the Kasitu Valley, where abundant ash-rich anthropogenic deposits offer valuable insights into the pyrotechnology and fire practices of hunter-gatherer communities during the Middle and Later Stone Age.

To create a reference collection of ashes in thin section, I conducted controlled heating experiments on plants growing nearby the sites that are known to be used nowadays. The objective was to increase our understanding of the components of the archaeological ashes, their burning temperatures, and different ash shapes.

Examples of ash remains in the archaeological deposits from the rockshelter sites of Hora-1 and Kadawonda-1

For the burning experiments, I sampled both woody and non-woody plants, such as sedges and grasses.

Upon heating, the non-woody specimens transformed mainly into fibers, phytoliths, and siliceous aggregates.

Though most wood-ash looks very similar in thin section, with rhombohedral calcite pseudomorphs after calcium oxalates dominating, some of the rockshelter deposits in Malawi contain different, more characteristic shapes.