Bundi Rafting Route and Geology
The route begins at the Bundi River Rafters Camp and follows through to Aussenkehr. The guides gave informal names to many landmarks along the Orange River during their explorations. Here is the geological background of these landmarks.
Yellow-weathering cliffs are of sedimentary origin and are part of the Dwyka Tillite Formation of the Karoo Supergroup. They are approximately 300 million years old. After the river reaches its left bend, the outcrops continue to outcrop and turn black near river level. Keep an eye out for large dropstones within the tillite exposures.
On the way out of the camp, a series of sheer grey limestone cliffs rise from the left bank. A limestone deposit of about 540 million years ago settled in shallow waters. They are part of the Nama Group. Similar to the tropical coral reefs of the Caribbean today, it would have existed as a planar or wavy mat primarily composed of primitive algae.
Consider the thick limestone beds. Each of their laminae represents a different season of annual accumulation, very similar to the growth rings of trees. Counting up these thin laminae can tell you how long it took to deposit the whole cliff thickness. It probably took several thousands of years. From a distance, the thick limestone layers appear as broad, wavy patterns known as open folds. Strata exert pressure on the beds, which bend as a magazine does when folded. The cliffs bounce sound back in a dramatic fashion, with distance influencing the echoes. Try shouting at the river or smacking it with your paddles.
A sheer wall of Nama limestones rises out of the river, dwarfing even the Echo Krantzes. There is a vertical crack about halfway along Echo Cliffs, where displacement has occurred. 300 million years ago, this crack caused a break up of Gondwanaland, likely caused by an ancient earthquake.
Several of these faults led to the splitting of the continent and ultimately contributed to South America’s separation from Africa. The ocean now obscures all the major rift faults along the coast, so we have to hunt for their smaller associated fault breaks, which we can see extend quite far inland.
Also called “Thumbprint” or “Swiss Roll”. Snail represents a more smooth fold structure because of the buckling caused by Gondwanaland’s rifting. The Echo Cliffs faults and snail folds developed along the edge of a graben which preserved the Nama Group.
Peace of Ashes – Petroglyphs
The Nama limestone blocks, which have fallen from behind the left bank of the river, that are smooth and flat on their surfaces appear to have preserved San rock paintings (Petroglyphs) beyond Echo Cliffs and below Snail.
At the confluence of the Stinkfontein River, an imposing tower rises abruptly from the left bank. As a result of its floods, this river shifted the Orange to the right, washing out the boulder field. A dyke that runs along the Orange has been compared to the face of the movie monster due to the apparent joints and pits in its pattern. One favourite pastime at KK is camping on grassy terraces, while on the tower, one can get spectacular views of Richtersveld and Canyon Mountains.
Sjambok Fluorspar Mine
Richtersveld granite forms parts of the south wall of Sjambok Kloof near the Orange River. This area has been a source of fluorite (or fluorspar) since the early 20th century. Fluorite dumps still remain below the cliffs. Many river travelers grind some of them into powder and throw it onto the coals of a fire. Fluorite reacts to the heat by becoming luminescent, glowing a pale blue color and popping vigorously due to the thermal stress. The purest grades of fluorite are a source of fluoride for hydrofluoric acid manufacture or are also usable in the far-ultraviolet range, where conventional glasses are too absorbent for use.
7 Pillars Mine
From my understanding, the name derives from Proverbs, comparing Wisdom’s house as being built from seven pillars with the creation of a mine by the late Rudi Beneke. Also, the massive table mountain of quartzite that looms over the mine workings has a series of vertical fissures that give the appearance of several pillars. Diamonds have been recovered from ancient gravel terraces that are perched above the modern channel of the Orange River, attesting to a greater flow in the distant past. The river continues to cut down the canyon wall resulting in portions of these terraces remaining high above.
A fanciful comparison to the long pointed hats worn by these much maligned women, the Witches refer to a series of eroded quartzite towers that rise sheer from the Orange River canyon. In the Rosyntjieberg Canyon, the Orange turns almost to a right angle and then curves in a series of arcs. Quartzite ridges dominate the landscape along this slope, the first seen from afar over a spacious expanse of still water. A dense bed of quartzite makes up Witches Hat.
Some of the quartzite towers that border the Rosyntjieberg gorge contain sedimentary layers that reveal the origin of the hard grey rock. Erosion of the overburden revealed these tightly folded layers, which now appears as steep lines, or scratches, in the canyon walls. Inter-bedded with the pale quartzite are thin bands of black rock full of the iron oxide mineral magnetite. The sharp contrast of black and white beds in close proximity probably highlights the vertical structures.
Some of the quartzite towers that border the Rosyntjieberg gorge contain sedimentary layers that reveal the origin of the hard grey rock. Initially laid down in shallow seas nearly 2000 million years ago as clean white sand, much like that seen on all the west coast beaches today. A deep burial and pressure caused the sediment to harden, which subsequently buckled under long-term earth movements. Due to erosion, these layers became tightly folded, resulting in steep lines and scratches in the canyon walls. Inter-bedded with the pale quartzite are thin bands of black rock full of the iron oxide mineral magnetite. The sharp contrast of black and white beds in close proximity probably highlights the vertical structures.
As the Orange River is surrounded by broad plains on both sides, it seems very sedate and resembles a huge lake that has virtually no current flowing through it. When paddling this section there is a lot of work involved, especially if there is a strong headwind (divorce straights), since inactivity will make you retrace your steps upstream. Both banks are thickly forested, the left masking the diamond workings, and the right bordering the vast irrigated plains of table grapevines and many other fruit and vegetable crops. Despite the weak flow of the river, the only sound is that of the pump siphoning water into reservoirs.