Border Cave: Human Life in the Lebombo Mountains

Where is Border Cave?

Border Cave lies on the border between South Africa and eSwatini, formerly called Swaziland in older publications. A 1978 geological study placed it at approximately 27°1′19″ south, 31°59′24″ east, a little over 600 metres above sea level, about 12 kilometres north of Ingwavuma and approximately 82 kilometres in a direct line from the present Indian Ocean.

It is not a coastal cave. It faces west across the Lowveld, just below a steep escarpment rim, with access from above by a ledge or from below by a long slope. Its position offered shelter and a view across a varied catchment of mountains, lowlands and river corridors.

Geological setting

The cave formed in volcanic rocks of the Jozini Formation, part of the Lebombo Group. Modern dating places relevant rhyolite at approximately 182 million years old, in the Early Jurassic. Volcanic layering, cooling, fractures, chemical weathering, mechanical breakdown, uplift, tilting, erosion and river incision shaped the setting.

Differential weathering of stronger and weaker rhyolite layers created a recess that enlarged into a rock shelter. The cave did not create the Lebombo Mountains; ancient geology created the setting in which the shelter formed, and people later used it.

How old is the human evidence?

Human remains and burial

Border Cave has produced remains of several human individuals. Older publications describe Middle Stone Age remains as anatomically modern Homo sapiens. One important find is an almost complete infant skeleton associated with a burial; later summaries place the child at approximately 82,000 years old.

The burial was associated with ochre. The responsible wording is: “Border Cave preserves evidence of a deliberate child burial associated with ochre. The find demonstrates complex cultural behaviour, while the precise meaning of the ochre remains unknown.” It should not be used to assign a modern ethnic identity to people who lived tens of thousands of years before modern political, language and ethnic categories.

Fire, ash and grass bedding

Research reported in 2020 identified grass bedding at least 200,000 years old. Bedding was placed on ash layers near the back of the cave. Ash may have created a clean surface and reduced crawling insects. Plant remains included broad-leafed Panicoideae grass and camphor bush in the oldest bedding context.

Stone-tool debris mixed with grass suggests work took place on or near bedding surfaces. Hearths and ash show repeated fire use. People were modifying their living space for sleeping, resting, working stone, processing plant and animal material, managing fire and possibly using medicinal or insect-repelling plants.

Tools, ochre and ornaments

Finds include rhyolite, chert, chalcedony and quartz tools; bone points; later wooden tools; ostrich-eggshell and marine-shell beads; engraved or notched bone; perforated stones associated with digging sticks; ochre; poison-related residue on a wooden applicator; and later Stone Age artefacts associated with bow-and-arrow technology.

Local rhyolite shows use of nearby resources, while chalcedony and marine shell indicate movement, exchange or access beyond the cave. Marine shell does not mean Border Cave was on the coast; it shows that coastal material could enter an inland mountain network.

Ice ages and climate

Southern Africa did not experience a continental ice sheet covering the Lebombo Mountains. It experienced glacial-interglacial changes in rainfall, moisture, seasonality, wind, vegetation and temperature. The Last Glacial Period lasted approximately 115,000–11,700 years ago; the Last Glacial Maximum was roughly 26,000–19,000 years ago.

Border Cave is older than the last glacial period and records several environmental phases. Sediments contain cycles, weathering horizons and rubble that have been interpreted as possible frost-weathering, while clay-rich palaeosols indicate periods of greater moisture and chemical weathering. These are scientific reconstructions affected by human activity, fire, roof fall and later chemical processes.

Did the ice age create the landscape?

No. Ancient volcanic geology, uplift, tilting, erosion and river incision established the Lebombo structure. Climate changes later influenced vegetation, soil moisture, river flow, animal habitats, fire regimes, erosion and human strategies. Old geology created the mountain and cave; climate modified the habitats around it; people adapted to both.

The coastal connection and Port Durnford

Border Cave is inland, approximately 82 kilometres from the Indian Ocean in the direct-line measurement used by the 1978 study. During the Last Glacial Maximum, sea level was approximately 120–130 metres lower, exposing more shelf and moving the shoreline seaward. Later sea-level rise reshaped estuaries, lagoons, wetlands and coastal habitats.

The Port Durnford Formation is a separate Pleistocene coastal sequence associated with barrier-lagoon, marine, lagoonal, terrestrial, mud, peat and sand deposits. It was not created by Border Cave. Border Cave records inland mountain occupation and climate; Port Durnford records coastal and lagoonal environments. They are compared as regional evidence, not as cause and effect.

Why Border Cave matters

The cave connects volcanic geology, rivers, lowlands, coastal plain and ocean. It preserves decisions: where people slept, how they prepared fire, shaped stone, carried plants, placed a child and returned to a shelter. The landscape is an archive of geology, climate, technology, symbolic behaviour and movement.

Scientific references