Border Cave sits high in the Lebombo Mountains along the border of present-day South Africa and Eswatini. Archaeologists have excavated the rock shelter since the 1930s, though recent work has revealed unusual preservation of organic materials, including ancient grass bedding. Researchers from the University of the Witwatersrand examined the deposits at a microscopic level and identified six different bedding microfacies, or microscopic sediment patterns linked to different types of bed construction and maintenance.
Only a few African Stone Age sites have produced bedding remains studied in such detail. Earlier microscopic work at Sibhudu Cave and Diepkloof Rock Shelter provided much of the current understanding of ancient bedding practices. The new study greatly expands the sample from Border Cave and shows a wider range of preserved bedding structures than previously known.
Some of the newly identified microfacies closely resemble bedding types from the other South African sites. Others appear unique to Border Cave. The differences include variations in ash content, the arrangement of plant remains, and signs of trampling or burning. Researchers suggest these patterns reflect differences in how people maintained their living spaces or the types of plants selected for bedding.
The study found repeated evidence that people often built beds on layers of ash. In many cases, bedding materials rested directly above ash deposits or mixed with ash-rich sediments. Researchers believe ash may have helped keep sleeping areas dry and warm while also discouraging insects. Earlier studies at Border Cave proposed a similar function.
The evidence does not always show whether people intentionally spread fresh ash before laying down bedding or reused ash already present on the cave floor. Some ash deposits appear thick and concentrated, while others form thinner scattered layers. Still, the repeated association between ash and bedding suggests this practice formed a regular part of cave life for thousands of years.
Microscopic analysis also revealed signs of repeated maintenance. Some bedding layers had been refreshed with new plant material, trampled by human activity, and partially burned several times. One especially well-preserved “grass mat” from younger deposits contained several overlapping layers of dried and charred plant remains. Researchers describe this as the first detailed microscopic study of such a preserved Stone Age grass mat.
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