The Moving Cataract: Mosi-oa-Tunya, Victoria Falls: UNESCO Culture Sector

Let’s walk up to the tourist viewing area. It should be possible to have a panoramic view from here… but, not at all. The sky above is clear, but the water keeps pouring down as if we were in a heavy rainstorm. "You must have an underwater camera!"

To have a full view of visitors have to wait till the dry season, when the water volume decreases. This is the view from the same point in the dry season. The waterfall is about 1,700 meters wide and drops about 110 meters, the width of the gorge where the water falls is only about 100 meters. This is downriver of the falls. While the river above the falls is slow and steady, downriver it zigzags through narrow gorges. There used to be a water fall over this steep cliff. The fall has been moving upstream over time.

About 180 million years ago, magma spewed out of the ground and created a basalt plateau. When the plateau cooled down, it solidified and a countless number of crevices were formed. Later, the plateau was submerged under a lake where mud and decaying matter were deposited between the cracks. The plateau rose again and those deposits became soft sedimentary rocks.

The Zambezi river started to run across the plateau later on. The river eroded away the sedimentary rocks at the most downstream area of the plateau and the first waterfall was created. This took place about two hundred thousand years ago. Gradually sedimentary rocks were eroded one after another, and the fall slowly made its way upstream.

Gorges created in the lower area tell us the history of this moving waterfall. This is where the first waterfall was formed about 80 km downstream from the current one. It could be described as a 200 thousand year old waterfall fossil. This is where the second fall was. It is believed to date back to 180 thousand years ago. Homo sapiens already existed at that time and possibly saw this giant waterfall.

The current waterfall is the 8^th. The front edge erodes at a rate of 10 centimetres per year. Upriver we can see evidence of new cracks which could become the next waterfall. It is the small gorge seen in the centre of this shot. When the next fall is made the last one ends its role and becomes a gorge.

The long journey of the Victoria Falls still goes on.