Border Cave

Border Cave is a rock shelter high on the western scarp of the Lebombo Mountains in KwaZulu-Natal, South Africa, close to the border with Eswatini. Its deposits span the Middle Stone Age to the Iron Age, and they include the oldest known evidence of deliberately laid grass bedding. For a history of roofing, the site illustrates the earliest stage of shelter: a natural rock overhang used as a roof, furnished with plant material on the floor.

Setting

The west-facing shelter lies at about 600 m (2,000 ft) above sea level, roughly 100 m (330 ft) below the crest of the range and about 12 km (7.5 mi) north of Ingwavuma. Its oldest deposits are about 250,000 years old by luminescence dating, with ESR and radiocarbon results of 227,000 ± 11,000 years; the youngest layers date from about 41,000 to 24,000 years ago.

Grass bedding

A 2020 study in Science led by Lyn Wadley described grass beds in layers dated between about 227,000 and 179,000 years ago. The beds are made mostly of grasses of the subfamily Panicoideae, with occasional sedges and leaves of broad-leaved plants, and were laid near the back of the shelter. In all, 48 bedding layers were identified. Charcoal in the bedding and alternating bands of brown sand and white ash record repeated burning; burn marks occur mostly at the edges of the beds. Regular burning appears in the plant-microfossil record by about 170,000 years ago. Rhizomes of Hypoxis found in hearths suggest that plant foods were cooked.

Significance

Plant shelters and roofs rarely survive, so evidence for early building is indirect. Border Cave shows that by about 200,000 years ago people in southern Africa were returning repeatedly to the same shelter, managing fire and preparing the floor with grass, the same material that later formed the thatched roofs of the region.