Victoria Falls National Park, Zimbabwe

Located on the Zambezi River, about 621 miles from its source, the Victoria Falls are Zimbabwe's best-known geographical feature and tourist attraction. With a width of 5600 feet and an average depth of about 328 feet, they form the biggest single curtain of falling water in the world.

The flow of water over the Falls varies according to the time of year and the rainfall in the Zambezi's upper catchment areas in western Zambia and Angola. In November and December it may be only 706 000 cu feet per minute but towards the end of a normal rainy season it reaches 17 650 000 cu feet or more per minute. During the record- breaking floods of 1958 it reached a peak of 24 710 000 cu feet per minute. The Falls take the form of a sheer-sided chasm, as little as 197 feet wide in places, running almost at a right angle across the river width. The southern lip of the gorge creates a natural viewing platform from which the full extent of the Falls can be seen at close quarters.

Formation

Some 19th century European explorers of central Africa, such as David Livingstone, believed that the Falls were created by a cataclysmic rifting of the earth's crust but geologists who later visited the area realised that the Falls and the gorges downstream had been cut by the erosive power of the river.

Until the beginning of the Pliocene era, about 11 million years ago, today's upper Zambezi may have flowed southwards to join the Orange River in South Africa; subsequently, a gentle upwarping across the river's course may have caused its waters to form an inland sea in northern Botswana.

These waters later spilt eastwards across a depression in a basalt slab which had been pushed up to the earth's surface during the Upper Karoo era, some 150 million years ago, and which had become covered in sediments. The newly aligned river removed these sediments and began to cut back through the basalt, creating the Batoka Gorge.

However, near the Falls themselves, the basalt is criss-crossed by traverse faults; the softer material that filled these faults was excavated by the river, creating a succession of waterfalls. The Victoria Falls represent the latest in this series of faults and are cutting back at their western end, at Devil's Cataract, into another fault that will form the Victoria Falls of the future.

Peoples

The gravels in the area form one of southern Africa's richest archaeological sites; within them have been found implements ranging from pebble tools to the delicate microlithic artifacts of the Late Stone Age.

By the mid-19th century, the area was occupied by the Makololo, a Sotho group who had migrated from the Transvaal and who for a brief time dominated the other people living in the area, the Leyas, Lozi, Tokas and Subiyas.

The Makololo called the Falls Mosi oa Tunya, meaning 'the smoke that thunders'; however, when Livingstone arrived at the Falls he renamed them after the reigning queen of the British Isles, Victoria.

Conservation

Since the completion of the Victoria Falls Bridge in 1905 the history of the Victoria Falls has been one of the development of tourism. The area has successfully avoided the excesses that have marred similar scenic tourist attractions elsewhere in the world.

On the Zimbabwean side, the only evidence of human intervention is the network of paths and viewpoints sited within the Rain Forest on the lip of the gorge opposite the Falls.

The Rain Forest, despite its popular name, is not a true rain forest; it is really only an unusually dense and extensive piece of riverine forest and is composed mainly of the ebony, fig and mahogany trees common to most riverine woodlands in Zimbabwe.

However, it does contain several rare herbaceous species; one species, a fern, Cheilanthes farinosa, is found nowhere else in the world apart from in two localities in Zambia. The forest is inhabited by some smaller mammals, including warthog, vervet monkeys and bushbuck. Within the gorges are many raptors, notably the black eagle and the Taita falcon.

The Victoria Falls are part of the 5 782 acres Victoria Falls National Park. Because of their unique scenery and geological interest the Falls have been designated a World Heritage Site under the UNESCO World Heritage Convention, to which Zimbabwe is a signatory nation.