New microscale insights into plant-based bedding construction and maintenance between 200 000 and 43 000 years ago at Border Cave, South Africa

The construction and maintenance of plant-based bedding in Stone Age contexts have received increasing attention in recent decades, as have the evolutionary implications of these behaviours. However, much of the current understanding of the microscale properties of Stone Age bedding comes from the micromorphological analysis of deposits at three Middle Stone Age sites in South Africa: Sibhudu Cave, Diepkloof Rock Shelter, and Border Cave. The latter site has yielded the oldest confidently identified bedding remains at ∼200 ka, but only a very limited portion of the site's long sequence has been investigated at the microscale. Given how little information is available, the Border Cave sequence provides an opportunity to significantly enlarge the global sample size of microscopically analysed Stone Age bedding. Here, we describe and interpret six bedding microfacies identified through micromorphological analysis of Border Cave deposits spanning 200 to 43 ka. Several of these microfacies closely match those reported from Sibhudu and Diepkloof but differ in small, but potentially significant, ways. These differences could reflect inter-site variations in bedding construction and/or maintenance or be due to the plant material utilised. Three microfacies, associated with ‘grass mats’ in younger members, do not have published equivalents. These younger deposits underwent comparatively limited disturbance by past human activities, which likely played a significant role in their high degree of preservation. Alongside broadening the known diversity of Stone Age bedding, the new observations provide nuanced insights into variations in degrees and types of bedding maintenance, and varying impacts of other anthropogenic post-depositional processes, though the Border Cave sequence. Resulting inferences of occupational intensity broadly conform to those derived from artefact densities, but there are also indications of short(er) periods of intensive occupation during the formation of some members that otherwise reflect very low occupational intensities.