Fish River Canyon
The Fish River Canyon, located in Namibia, is the largest canyon in Africa and the second largest in the world. It is one of Namibia’s most visited tourist attractions.
Encompassing a total area of 5900 square kilometres, the canyon is made up of a massive gorge which approximately 180 km long, 27 km wide and over 500 meters deep in some places. While it’s considered to be small when compared to the Grand Canyon in the US, it is still a sight to behold.
The forces of water, wind, ice, and gravity have contributed to the 650 million year formation of this masterpiece. The Fish River Canyon is made up of a wider upper canyon and a narrow lower canyon. The lower canyon was formed after erosion had finally worn through the hard *gneiss bedrocks.
650 Million Years ago, a north-south *graben was formed by plate movement. The ancient Fish River flowed along this graben and eventually eroded the sedimentary rocks along the graben edges away, leaving a flat plain which is now the upper canyon. Glaciation during the Karoo Ice Age (360 – 260 million years ago), caused the canyon to further deepen.
When Africa and South America separated as Pangaea broke up, Africa’s elevation rose considerably, increase in the gradient of the Fish River. This steeper gradient and faster water flow increased the power of the water and allowed it to begin eroding the lower canyon into hard, metamorphic gneiss* bedrock that had previously resisted erosion, cutting the inner canyon seen today.
Different colours of rock strata can be seen along the length of the canyon.
The river is generally dry but floods in the region’s rainy season which is usually between January and April.
The area is known to be a semi-desert with temperatures rising up 50 degrees Celsius during the day and dropping to just over 30 degrees Celsius at night. The average annual rainfall is 100mm. In the winter months, temperatures can be expected to drop below 0 at night, yet it can reach well above 30 degrees Celsius during by midday. Despite this temperature fluctuation, there are over 50 species of bird life spread throughout the canyon. In the lower regions, antelope and baboons can be seen. Sightings of leopards and mountain zebra have also been reported.
*gneiss – high grade metamorphic rock
*graben - is a depressed block of land bordered by parallel faults
Image source http://bit.ly/1G9Um5H
References/Further reading http://bit.ly/1FYofAu