Monday 1 December 2014

Bank Sinkholes Trip by Gerrie Pretorius

On Sunday the 10th of August 2014, SEC went to check out some Sinkholes marked from Google Earth in the Bank area, in search of new caves.

The first sinkhole that we stopped at could be climbed down on one side without any rigging.

Unfortunately this Sinkhole didn’t lead to any new cave, but this was expected, very few sinkholes will actually have an open entrance into a cave system, especially in this area, where the dolomite is supposed to be far below the surface, although there is no shortage of sinkholes in the area.

After that we moved on to what we now call the “Moonscape”. The area has so many sinkholes in looks like the surface of the moon, expect we have sinkholes instead of craters. There are probably more than a hundred sinkholes here, and a small river stream running into the area, but not out on the other side.

On only the 3’d sinkhole we looked down in the Moonscape, we could clearly see it was going into a cave. The sinkhole was very small, so small it’s basically not even visible from Google Earth, yet it was very deep.

I was so excited. John quickly brought the Landy closer from which we rigged the bipod, while Rick suited up to go down and check it out.
Image: Gerrie Pretorius
I highlighted the sinkhole in yellow, and the bipod in blue, with Selena and Irene standing in front of it. If you walked here in the night, you would probably stumble into it without ever seeing it.

While Rick went down Steven and I checked out the rest of the sinkholes.

We stumbled onto some illegal miners and then where a stream disappeared into the ground we found a small cave in another sinkhole, which went about 15m before ending as it was clogged up with mud. Another sinkhole within a sinkhole was really deep, and disappeared into the blackness, but rigging this was not a viable option as the area around it looked really unstable.

Another sinkhole was rigged with a ladder, but the dark side of it was only a dark side, with no real cave.

Back at Rick’s sinkhole, and unfortunately Rick reported that this is a cave but a very small one, and also doesn’t really go past 20 meters.

Rick, was still full of energy at this point and volunteered to descend another deep sinkhole. Unfortunately this was also dead.
Image: Gerrie Pretorius
We then left the moonscape area to check other sinkholes in the area, with no result, and then moved on to Jockstrap Cave.

After a quick glance down the side of Jockstrap, it was clear that there were new developments since our last trip there in 2008. Besides the main cave that we discovered on our previous trip, there was a second area that seemed to go a bit. John quickly climbed down to check it out. Indeed it went further. After John disappeared for about 10minutes, he came back reporting that although it goes further, it still died out in mud, but noted that we should visit it again in a few years time as it is the sinkhole is still regularly changing.

About 500m behind Jockstrap lies three more sinkholes, all three are positioned around an old house, we named it the Lucky House Sinkholes.
Image: Google Earth
Although I’m not sure how lucky this house really is, as it looks like a part of it definitely disappeared down the sinkhole, not to mention the fact that you can climb down underneath the foundation of the house as the long sinkhole gave away underneath the house.
Image: Gerrie Pretorius
Right there in the long sinkhole we could see a passage disappearing into the dark, going perpendicular to the sinkhole, again I got all excited, Steven went in, but unfortunately this was also only a small 10m cave.

Another 500m behind the Lucky House Sinkholes, were three more sinkholes and they were spectacular. One of these sinkholes formed right underneath a big pipeline, swallowing the ground and the pipeline. From the top it looked like this sinkhole definitely went.

We rigged a tyrolean across, between two cars, and Rick disappeared into the cave.

Image: Gerrie Pretorius
After a long wait Rick was still missing, and Steven decided to go down as well to see what he had found.

Just as Steven finished his descent Rick came from the dark, reporting that this is a cave big enough to be worthy of a survey.

Rick and Steven then disappeared together to survey the cave.

Meanwhile, waiting for rick and steven, John decided to descend second sinkhole 30 metres from Rick and Steven’s pipeline.

He tied off with a 60 metre rope and descended along a nearly verticle slope. A while later he realized that the 60 metres wasn’t enough, and we helped him extend the rope with another 60 metres. The sinkhole went down nearly but near the visible bottom started sloping away into the darkness, it was this slope that caught us off guard, continuing much deeper than we had anticipated.

Image: Gerrie Pretorius
After doing a changeover and the rest of the descent, John came back with a cave of roughly 60 meters passage past the entrance, that also looks promising for the future.

Steven and Rick were still busy surveying the sinkhole next door so we went to the third sinkhole. This one was really massive, although not very deep. It was definitely the oldest one of the three. In the middle of this sinkhole, we found something, and our hopes went up, between some big boulders there was something going down, and it looked really promising, it turned out to be a two ladder pitch for which John volunteered, but soon returned, and unfortunately it didn't go much further after the ladder pitch.

Steven and Rick returned with 150 meters of surveyed passage and we started heading back home while checking a last few sinkholes that were on the way.

Another series of sinkholes formed over the same pipeline although this was about 3 to 4 kilometres away from where the previous ones were and about 300 meters from here right next to the gravel road, we found another sinkhole. The diameter was not massive, but it’s deep... real deep! In fact we could not see the bottom at all.

Image: Gerrie Pretorius
Unfortunately time was against us and we had to leave it for another day.

Thanks all for this trip.

Exploring known caves for new extensions is fun, but known caves are known because someone went to look for them, and found them. Who knows how many are still out there, waiting to be found.

Thanks Steven Tucker, John and Selena Dickie, Irene Kruger and Rick Hunter for an awesome trip!

Gerrie Pretorius

1 comment:

  1. Great write-up, Gerrie! Sorry I missed this trip but your story tells me plenty...............and next time - who knows?