Milner Vlakte 1 Cave
Peter Swart March 1996
Introduction
Looking up from Milner Vlakte, towards the Shale Peaks, one cannot help but notice a large black spot on the mountainside. On closer inspection, the black spot turns into a large cave entrance, 10m high and 30m across. The floor of the impressive entrance chamber is covered in rock debris, and roof consists of 5 large arches, with skylight slots in between them. Morgan Behr found a description of the cave in a Mountain Club Journal (
Lotz, 1975) and visited the cave at the end of 1995. He was instantly declared the resident on the cave, and was persuaded to lead a SASA meet to Milner Vlakte.
Survey and Exploration
Our rather full weekend started on Friday evening, when we camped at the foot of the mountain near, a dam. We turned in early, as Morgan had on the March before 6am. We climbed up to the Vlakte, and camped within about an hours walk of the cave. After a brief lunch we made our way to the entrance, and were greeted by the welcome coolness of the entrance chamber. While Alister, Celeste and Rosemary went for a walk, Morgan, Daryll Holland, Anthony Keen, Joan Vlok and I set about surveying the cave. By 4pm we had finished the survey, and went across to a second cave where we stopped for tea. By this stage we were quite tired, and were running out of time. We explored the second, smaller cave, and decided that a second trip would be needed to survey it.
An exhausted party returned to camp. After supper, to clouds rolled in, and it poured with rain. On Sunday morning, we beat a hasty retreat, and were back at the cars by early afternoon.
Cave Description
The cave is a 100m long, 30m wide tube that runs down, the mountain, parallel to the slope. In the entrance chamber of the cave, the floor is littered with boulder debris from collapses, and the chamber is lit, not only by light from the huge entrance, but also from wide joints in the roof. These joints separate 5 rock arches, which fuse in places, to form the roof of the entrance chamber. The floor of the cave rises with the mountain slope, at an angle of approximately 25 degrees. There is an entrance half way along the cave, and another at the top end.
From the main, lower entrance to the middle entrance, much of the floor is formed by large boulders which have fallen from the ceiling, but between the middle entrance and the rear entrance, the floor is bedrock, which has been polished by flowing water. Along most of the length of the cave, silica formations occur. Some of these form small stalactites, while others form silica popcorn. Many of these are in the form of a crust, and have formed on top of the major floor debris. This indicates that some of the larger collapses occurred a long time ago.
The top entrance of the cave is formed by a collapse in the plate that forms the roof of the cave. The collapse divides the top entrance into northern and southern parts. The southern entrance is low and narrow. The small stream that flows into this entrance makes the floor very slippery, despite the numerous small ridges in the floor. The northern entrance is quite large, and leads down into the cave over a boulder strewn slope. The roof and floor of the passage along the northern wall are covered with small silica formations.
Conclusion
Just to the east of the main cave, is the second cave. Although it is not as big as the main cave, it is just as interesting. Unfortunately, we did not have time to survey the cave. The topography of the area suggests that these are not the only caves in the area, and further exploration may well reveal more caves.
The traditional view amongst cavers in the Western Cape, is that high concentrations of sandstone caves in this region only occur in the Cape Peninsula. These caves in the Hex River Mountains, the nearby caves on the University of Cape Town Zuurberg property, and the caves at Die Hel in the Groot Winterhoek, suggest that this may not be true. Many more caves but may well be distributed throughout the mountains of the Western Cape, waiting to reveal themselves to those who actually go looking for them.
Bibliography
Lotz, E. 1975; Cave on Milnervlakte Hexriver Mountains. Journal of the Mountain Club of South Africa, Vol 78, p79, 1975
