Friday geology photos: Fish River Canyon

The Fish River Canyon is one of Namibia's many wonders. The canyon is marketed as the second biggest in the world after the Grand Canyon. At 550m maximum depth and 160km long it is definitely a baby compared to the Grand Canyon but the Fish, as it is affectionately known, is a fantastic place in its own right. The first photo is from the view point at Hobas, which is the starting point of the Fish River hiking trail. The trail is 65 to 90km depending on whether you stick to the river course or cut across the meanders. The latter is far more fun, cool rocks and the added bonus of a break from the sand. The canyon is open to hikers from May to September each year. Flash flooding and high summer temperatures make it dangerous to hike from October to April. The photos below were taken when I hiked the canyon in September last year (2010).

The geology in brief
Doming related to the African Superswell is thought to have resulted in the Fish incising its bed. There are beautiful exposures of the nonconformity between the ~550-750Ma sediments of the Nama group and the +1000Ma Gordonia Subprovince, migmitites and granite gneisses. These rocks are cut by two sets of dolerite (diabase) dykes one associated with break-up of Rhodina, which abuts against the Nama sediments. The second is related to the break-up of Gondwana. These are the youngest rocks in the canyon.

View from Hobas look out point

Migmatite :)

Noncomformity between the Nama sediments (top) and the Gordonia migmitites (bottom)
The dark band is one of the older dolerite dykes

Desert horses. They are the descendants of escapees once owned by the German colonisers.

Grunert, N., (2000) Namibia - fascination of geology: A travel handbook. Klaus Hess Publishers, pp 176

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