Early-to-Mid-Holocene Continuity and Change Revealed at Strathalan Cave Excavations

Archaeologists excavating a sandstone cave in South Africa have uncovered a remarkably detailed record of human activity spanning thousands of years, revealing how hunter-gatherers used fire, plants, stone, bone and animal resources as the climate and landscape changed. The preliminary findings from Strathalan Cave A, in the foothills of the Drakensberg in the north-eastern Cape, show that people repeatedly returned to the shelter between roughly 9,500 and 5,300 calibrated years before present, with the most intensive occupation occurring around 7,200 years ago. Evidence of later visits extends into the last millennium and possibly the historic period, making the cave a rare archive of long-term continuity in a region where archaeological research has been comparatively limited.

Strathalan Cave A lies beneath a sandstone overhang at an elevation of about 1,340 metres, where the high Drakensberg meets lower grasslands and valleys carrying both summer-grazed sourveld and year-round sweetveld. The location would have offered shelter, access to water and proximity to diverse animal and plant habitats. A perennial waterfall runs across the larger cave complex, while nearby grasslands historically supported species such as eland, zebra, blesbok and mountain reedbuck. The site also occupies a possible crossroads between ecological and social networks linking the interior highlands, the Eastern Cape and areas nearer the coast. That geographic position may explain why the cave remained attractive to mobile communities over much of the Holocene, the geological epoch that began about 11,700 years ago.

The new excavation focused on three adjoining one-metre-square areas near the cave entrance. One square was dug down to bedrock, approximately 68 centimetres below the surface, allowing researchers to construct a reference profile for the deposits. Rather than relying solely on visible layers, the team excavated in five-centimetre spits and then grouped the sediments into three allostratigraphic units, meaning layers distinguished by major breaks in deposition and site formation. The lowest unit, A3, was a coarse, rubbly deposit resting directly on the cave floor. Above it lay A2, a dark, ash-rich layer containing combustion features and possible grass bedding. The upper unit, A1, was looser and more disturbed, containing dung, plant fragments and material affected by erosion, burrowing and later human activity.

Radiocarbon dating provided the chronological backbone for the sequence. Researchers submitted 16 charcoal samples for analysis, obtaining 15 usable dates after pretreatment and calibration with a Southern Hemisphere calibration curve. The ages generally form a coherent progression from approximately 9,000 years ago in the lowest excavated sediments to about 5,400 years ago near the top, although one sample produced a much younger age of roughly 799 years and may represent contamination or material that moved downward through the porous deposit. The dates support earlier work at Strathalan, which also indicated Holocene occupation. A cluster between approximately 8,000 and 7,000 years ago, centred on about 7,200 years ago, suggests that people used the shelter particularly intensively during this interval.

The most striking archaeological signal comes from unit A2. Unlike the relatively structureless layers above and below, A2 contains horizontally bedded ash, charcoal-rich deposits and localized combustion features. Some patches appear to represent intact or partly disturbed fires, while others may be dumped ash or reworked hearth material. Fibrous, humic lenses along the cave wall could be remnants of bedding made from grass or other plant material. Sediment chemistry supports this interpretation: A2 generally contains more moisture and organic carbon than A3, while its inorganic carbon content may reflect the chemical alteration of burned organic matter. Grain-size measurements also distinguish A2 from the surrounding cave sediments, showing a greater contribution from fine sands, silts and ash rather than the coarse particles released as the sandstone roof weathered.

The cave’s inhabitants manufactured nearly 2,000 stone artefacts in the excavated square, excluding the smallest chips. Flakes accounted for about 44 per cent of the assemblage, while chunks made up approximately 41 per cent. Hornfels, a hard metamorphic rock available in the surrounding landscape, was the dominant raw material, representing 67 per cent of the artefacts. Cryptocrystalline silicates, including chert and chalcedony, contributed another 23 per cent. The assemblage also contained 69 retouched tools, including scrapers, retouched flakes and a small number of backed pieces. Hornfels and cryptocrystalline silicates appear to have been worked in somewhat different ways, probably because their mechanical properties and natural shapes influenced how flakes could be detached. Yet the broad technological pattern changed little through the sequence, suggesting continuity in stone-working practices despite fluctuations in occupation intensity.

Bone tools add a more intimate dimension to the evidence. Microscopic wear on one modified bovid metacarpal indicates that it was probably used as a pestle. The bone’s rounded end, abrasion and tightly grouped striations are consistent with repeated contact against a stone mortar, while surface cracking suggests that the material being processed was moist. Fresh leaves, soft stems or other green plant matter may have been ground with the implement, potentially for food, medicine or other uses. Another small bone tool may have served as an ad hoc digging implement. A pointed bone fragment from the deepest excavated layer, dated to around 9,000 years ago, may have been used to process plant fibres. Together, these artefacts suggest that plant processing was not a marginal activity at Strathalan, even though such behaviour often leaves less visible traces than hunting or stone production.

Animal remains point to a varied but changing environment. The assemblage is heavily fragmented, yet mountain reedbuck, oribi, grey rhebok, zebra and several other bovids were identified, along with rock hyrax and rodents. More than a quarter of the analysed bone fragments had been burned, consistent with cooking, waste disposal or repeated fires. The lowest unit contained very few identifiable bones, but both specimens that could be identified to species were zebra, supporting the interpretation of a predominantly grassland setting during the early part of the sequence. In A2, the fauna included a mixture of grazers and animals with broader feeding habits. Later layers contained stronger evidence for grazing antelope. Because the sample is small, the researchers caution against treating these changes as definitive climate indicators, but they may reflect a shift in local vegetation or in the animals targeted by occupants.

Plant evidence provides an independent way to reconstruct the cave’s surroundings. Charcoal from the deposits includes numerous Protea fragments as well as wood from grassland trees and shrubs. Of the approximately 6,800 charcoal fragments recovered, 78 larger pieces were examined anatomically under reflected-light microscopy, allowing their structure to be compared with modern reference specimens. The presence of Protea may signal a cooler, more shrub-rich environment after the climatic disruption commonly known as the 8.2-kiloyear event, although it could also result from people preferentially collecting particular firewood. Phytoliths—microscopic silica bodies formed inside plant tissues—were also extracted from 15 sediment samples. Tree-associated forms were common, while grass and sedge indicators appeared in lower numbers. The results broadly suggest open grassland interspersed with thicket or woody vegetation, broadly similar to the modern landscape, rather than a dramatic transformation of the region.

The investigators divide the occupational history into three broad phases. The lowest phase, A3, represents relatively light use, with coarse sediments, few artefacts and limited faunal evidence. The middle phase, corresponding mainly to A2, contains the greatest concentration of lithics, bone and plant remains, as well as repeated combustion features and possible bedding. Its peak around 7,200 years ago may reflect longer stays, more frequent visits or a combination of both. The upper phase, A1, is more disturbed and includes abundant dung, suggesting later use of the shelter by herders or farmers as a livestock enclosure. Historical activity also altered the deposits: local farmers reportedly removed ash as fertilizer during the 1930s. Small pottery fragments, some possibly associated with later farming communities, were found in the upper sequence, although their movement through the loose sediments makes their precise dates uncertain.

Strathalan’s story extends beyond occupation layers and artefacts. Rock art at the complex includes imagery connected with San beliefs about rain, animals and supernatural power, while some engravings and a roughly painted bovine figure appear to belong to the post-contact period after domestic animals were introduced. The cave therefore preserves evidence of changing relationships between people and place from the early Holocene into recent history. The researchers emphasize that the excavation is preliminary: additional squares are now being investigated stratigraphically, with higher-resolution sediment sampling and further analysis of stone technology, animal remains, plant residues and site formation processes. Those studies could determine whether the changes in fire use, vegetation and animal exploitation reflect regional climate events, local environmental shifts, evolving social networks or simply different activities carried out in different parts of the shelter. For now, the evidence shows that the Drakensberg foothills were not an archaeological blank, but a long-lived meeting ground where people repeatedly adapted to—and helped shape—a dynamic mountain grassland environment.