The drive along the S52 from Shingwedzi is one of those highly recommended drives in the Kruger National Park. It takes you to a number of viewpoints, one of which is at the Red Rocks Geological site. The Red Rocks refers to a large sandstone slab exposed by the Shingwedzi River.
It is quite a long drive down a sand road to complete the full loop so the section has been split into 2. The drive down to the Red Rocks covers the first section on the south side of the Shingwedzi river and is a short drive from the main tar road. Thereafter the loop continue to the north side of the river back to the main tar road. This section can take a long time but is truly worth the effort.
The Red Rocks is best viewed in the early morning when the sun hits the rocks. You are allowed to get out of your car here, so pour yourself an early-morning cup of coffee from your flask and listen for the African Fish Eagle's call.
Similar red rock formations occur in a range of South African locations and are said to be the result of the Clarens Formation going back a very long time.
The Kruger National Park contains rocks that represent the earliest parts of South Africa’s geological history as well as relatively young lithologies. Archaean rocks present in the KNP include both Archaean granitoid intrusions and Archaean greenstone belt fragments. Archaean granitoid intrusions cover small areas within the western central and western northern parts of the Park.
The entire SW part of the KNP is underlain by rocks belonging to the Nelspruit Suite (see my Nelspruit’s Granite Suite EarthCache). The rocks of this batholith have an age of 3303± Ma (million years) and mostly consist of coarse-grained porphyritic granodiorites. These rocks are grey to pink and are composed of quartz, plagioclase, microcline and biotite.
Almost the entire eastern half of the KNP as well as a large area in the western central parts of the Park is underlain by rocks of the Karoo Supergroup and which is overlain by sedimentary rocks from the Clarens formation. Exposure of the Clarens formation is very poor in most areas of the park and is the best seen here at the Red Rocks site.
Geological Background of the Clarens Formation
The Clarens Formation is a buff-coloured, fine-grained arenite that ranges in thickness from a maximum of about 300 m in the main Karoo Basin, to less than 100 m in the Springbok Flats, Lebombo, Tuli,Tshipise and Ellisras Basins. It stretches from the south of Lesotho into the north of South Africa and into the south of Zimbabwe.
The gross lithological uniformity of the Clarens Formation led some casual interpretations of the unit as product of an overly dry,sand sea, in spite of detailed investigations presenting evidence for episodic wetter phases during the predominant aeolian deposition.
It consists of light-coloured, fine-grained sandstones, sandy siltstones and mudstones, and subordinate coarser-grained components. Fresh faces of the rock collected from boreholes and quarries are white, yet on exposure the rock weathers to give its characteristic tan or golden colour. However, there have been no detailed studies on the chemical and mechanical weathering processes causing such colour alterations.
The characteristic red colour in these Red Rocks however is to be believed the result from iron oxide (rust) coatings on the mineral grains in the rock. Iron oxide forms in relatively warm, oxidizing terrestrial conditions such as those that prevailed at the time.
The sandstone from the Clarens formation in this area attains a thickness of 10-35 meter and to the base contains about a 1 meter thick layer of limestone and calcareous concretions.
Weathering of rocks and minerals occurs by 3 different processes involving any or probably all of the following : chemical, physical and biological. The biologically induced processes result in either physical or chemical reactions being speeded up in the presence of water in particular. It has been postulated that the formation of the Red Rocks was enhanced by strong biological processes involving bacteria.
- Biological weathering involves the disintegration of rock and mineral due to the chemical and/or physical agents of an organism. The types of organisms that can cause weathering range from bacteria to plants to animals. Chelation is a process in which rocks are eaten away by acids from soil humus.
- Simple chemical processes like solution can be enhanced by the carbon dioxide produced by respiration. Carbon dioxide mixing with water forms carbonic acid.
- Erosion is the physical wearing down and removal of rock by the sea, rivers and streams, glaciers or even wind.
Organisms can influence the moisture regime in soils and therefore enhance weathering. Shade from aerial leaves and stems, the presence of roots masses, and humus all act to increase the availability of water in the soil profile. Water is a necessary component in several physical and chemical weathering processes.
Denudation is the combined result of weathering and erosion. Over thousands or millions of years, denudation can destroy even the toughest rock.
All these geological processes had part in creating these magnificent Red Rocks formations.
Sources used:
The General Geology of the Kruger National Park by I.C. Schutte (1986)
Wikipedia
www.sanparks.org
To log the cache you have to email me the answers to the following questions. Please do not post it in your log.
1. When you stand at the lookout point and you look to the cliff on your right, you will see a good example of sedimetary rock. Give a short explanation of what you see and what you understand about sedimentary rock.
2. How high do you estimate the top of the cliff is from the river?
3. Look across the river to the Red Rocks. What weathering process do you think formed these rocks?
4. For optional extra bonus points, what animals did you see around in this area.
Uploading photos to the cache page is the best way to say thank you to the cache developer and to encourage others to visit the location but is only optional.
Notes!!
1.) Remember that it is illegal (and dangerous) to get out of your vehicle at any place in the Park except at places especially designated and clearly marked to do so. Stay in the demarked area for your own safety. Do not cross the river to see the Red Rocks from close-up.
2.) As in any other place in the park, you get out of the vehicle on your own risk. Watch out for sharp teeth and claws that might be lurking in the bush, or in the trees, or behind some rocks, or on top of the rocks, or . . . . I think you get the picture.
3.) You can sent me your answers in either Afrikaans or English.
