EDUCATIONAL LOGGING REQUIREMENTS
In order to substantiate your visit and comply with the educational requirement for Earth Caches you have to submit your answers to the following questions to the cache developers via their profile:
For purposes of logging this cache you must answer the following four questions.
1) Is the rock making up the Baviaanskloof Mountains metamorphic, sedimentary or igneous rock?
2) When was the material for this rock deposited?
3) There is a rock "structure" next to the road at the published coordinates. What is it? (Llocational question)
4) Choose any one of the rock formations en route through the Kloof and describe what you see. Include details of the colours of the rock, bedding, angles and folds that you see. You can use the mountain in front of you at the listed coordinates, or any other mountain face.
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As soon as one enters the Baviaanskloof, either from the East at Kondomo or the West at Nuwekloof pass you are immediately struck by the breathtaking rock formations that have been carved out by the rivers that flow through the Kloof.
The Baviaanskloof Mountains are one of the large ranges of mountains that makes up the Cape Fold Belt which stretches from Port Elizabeth in the East, Cape Town in the South-west and the Cederberg in the North-West.
If one looks at a cross section of South Africa from South to North one can see the rocks of the Cape Supergroup dominate the South Coast. The Table Mountain Group (formerly know as Table Mountain Sandstone) is the part of this Supergroup that makes up the Cape Fold Mountains. This is shown in the image on the right. Pictures are worth a thousand words.
How were the Cape Fold mountains formed?
First the sedimentation. About 510 million years ago a rift developed, separating Southern Africa from the Falkland Plateau. This rift was flooded and became the Agulhas Sea. Sediments accumulated in this shallow sea until about 350 to 330 million years ago. This sediment was about 8 km deep and consolidated to form the Cape Supergroup of rocks. The massive beds of sand have hardened to become an extremely weather-resistant sedimentary rock that is still some two thousand metres thick in places. Then the folding. Closure of the rift valley, starting 330 million years ago, resulted from the development of a subduction zone along the southern margin of Gondwana. This caused the drift of the Falkland Plateau back towards Africa. This rucked up the Cape Supergroup into a series of parallel folds, running mainly east-west (with a short section running north-south in the west, due to collision with eastward moving Patagonia). The continued subduction (one plate moving under another) of the paleo-Pacific Plate beneath the Falkland Plateau and the resulting collision of the latter with Southern Africa, raised a mountain range of immense proportions to the south of the former rift valley. The folded Cape Supergroup formed the northern foothills of this towering mountain range.
That was the first stage. Then the weight of the Falkland-Cape Supergroup mountains caused the continental crust of Southern Africa to sag, forming an area into which the Karoo Supergroup was deposited. Eventually much of the Cape Supergroup became buried under these Karoo deposits, only to re-emerge as mountains when upliftment of the subcontinent, about 180 million years ago, and again 20 million years ago. This started an episode of continuous erosion that was to remove many kilometers of surface deposits from Southern Africa. Although the tops of the original Cape Fold Mountains were eroded away, they eroded much slower than the considerably softer Karoo deposits to the north. In this way the Cape Fold Belt "erupted" from the eroding African landscape to form the parallel ranges of mountains that run for 800 km along the southern and south-western Cape coastline today.
If you would like a more technical and detailed explanation on how the Cape Fold Mountains were formed then go to Wikipedia
To claim this Earth Cache as a find please send me an email with the answers to the four questions, your caching name and your email address through our profile.
You may log your find once you have visited the site and determined the answers to the questions. Logs not supported by the necessary email will be deleted. Please do not reveal the answers in your log!
The information to answer the questions can be found by reading the description of the cache and by an observation on the mountain.
References
Wikipedia
The Story of the Earth and Life by Terrence McCarthy & Bruce Rubidge ISBN 978-1-77007-148-3
Geological Journeys by Nick Norman & Gavin Whitfield ISBN 978-1-77007-062-2