Introduction
Victoria falls is one of the Seven Natural Wonders of the World.[1] David Livingstone, the Scottish explorer, is believed to have been the first European to view the Victoria Falls.[2][3] (see pre-colonial history, below), and this is the name in use in Zimbabwe. The older, indigenous name of Mosi-oa-Tunya is the name in official use in Zambia. The World Heritage List recognises both names.[4] While it is neither the highest nor the widest waterfall in the world, it is claimed to be the largest. This claim is based on a width of 1,708 metres (5,600 ft)[5] and height of 108 meters (360 ft), forming the largest sheet of falling water in the world. The falls' maximum flow rate compares well with that of other major waterfalls (see table below).[4]
The Eastern Cataract, on the Zambian side.
For a considerable distance above the falls, the Zambezi flows over a level sheet of basalt, in a shallow valley bounded by low and distant sandstone hills. The river's course is dotted with numerous tree-covered islands, which increase in number as the river approaches the falls. There are no mountains, escarpments, or deep valleys which might be expected to create a waterfall, only flat plateau extending hundreds of kilometres in all directions.[6]
The falls are formed as the full width of the river plummets in a single vertical drop into a transverse chasm 1708 meters (5604 ft) wide, carved by its waters along a fracture zone in the basalt plateau. The depth of the chasm, called the First Gorge, varies from 80 metres (262 ft) at its western end to 108 metres (360 ft) in the centre. The only outlet to the First Gorge is a 110-metre-wide (360 ft) gap about two-thirds of the way across the width of the falls from the western end, through which the whole volume of the river pours into the Victoria Falls gorges.[6]
There are two islands on the crest of the falls that are large enough to divide the curtain of water even at full flood: Boaruka Island (or Cataract Island) near the western bank, and Livingstone Island near the middle. At less than full flood, additional islets divide the curtain of water into separate parallel streams. The main streams are named, in order from Zimbabwe (west) to Zambia (east): Devil's Cataract (called Leaping Water by some), Main Falls, Rainbow Falls (the highest) and the Eastern Cataract.[6]