For a short distance the Kalambo River marks the boundary between Zambia and Tanzania. At the Kalambo Falls, it ceases to flow on a high plateau and plunges over the side of the Great Rift Valley in one vertical drop of about 221m. This is the second highest waterfall in Africa, about double the height of the Victoria Falls, and about the 12th highest in the world.
On either side of the falls there are sheer rock walls, and a large colony of marabou storks breed in the cliffs during the dry season. The falls themselves will be at their most spectacular towards the end of the wet season, in February or March, though are worth visiting in any month.
Though few visitors realise it, the Kalambo Falls are also one of the most important archaeological sites in southern Africa. Just above the falls, by the side of the river, is a site that appears to have been occupied throughout much of the Stone Age and early Iron Age. The earliest tools and other remains discovered there may be over 300,000 years old, including evidence for the use of fire.
It seems that the earlier sites of occupation were regularly flooded by the river, and each time this deposited a fine layer of sand – thus preserving each layer of remains, tools and artefacts in a neat chronological sequence. Much later, the river cut into these original layers of sand and revealed the full sequence of human occupation to modern archaeologists.
For years Kalambo provided the earliest evidence of fire in sub-Saharan Africa – charred logs, ash and charcoal have been discovered amongst the lowest levels of remains. This was a tremendously important step for Stone-Age man as it enabled him to keep warm and cook food, as well as use fire to scare off aggressive animals. Burning areas of grass may even have helped him to hunt. However, more recent excavations of older sites in Africa have discovered evidence of the use of fire before the time when we believe that this site at Kalambo was occupied.
The site is also noted for evidence of much later settlement, from the early Iron Age. Archaeologists even speak of a 'Kalambo tradition' of pottery, for which they can find evidence in various sites in northern Zambia. The Kalambo site is unusual, and thus important, because it is a place that has had a number of settlements throughout the centuries. Thus the remains of each can be found on top of the last, and a reliable time-scale can easily be established.
It seems that the early Iron-Age farmers may have gradually displaced indigenous hunter-gatherers from about the 4th century AD: no further Stone-Age remains are found after that date. However, oral history from northern Zambia, along with the extensive rock art around Kasama, speaks of a recent survival of hunter-gatherers alongside farming peoples.