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Offline roxenz

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Re: Caving anybody? Check this out!
« Reply #40 on: February 27, 2013, 03:58:27 pm »
Not so far, and I don't expect them to find any either because of the amount of mining activity in the area.


The mines have to dewater the general area in which they operate, to prevent the mines from flooding.  Most of the surrounding water is stored in the dolomites.  The mines on the West Rand have to pump this water from one compartment to another, because Rand Water Board needs the water for greater Jozi.  A "compartment" is a block of porous dolomite that is "sealed off" by relatively impervious dolerite dykes.  When a snot-nosed geo I had to map these things so that the mines and Rand Water could settle who was stealing whose water...

As the rocks surrounding the mines are dewatered, the water level goes down and these caves (which were filled with water) become dry.  Without the water pressure to help support the caves, they start to collapse.  Sometimes the collapsing area forms a chimney that continues to collapse until it reaches the surface - bingo! sinkhole.

That hilly area near Westonaria (near the old "North Shaft" of Western Areas Gold Mine) has a few sinkholes in it, where the softer Karoo sediments have aided the collapsing roof of caves.  There was one that the mine tried to fill with waste rock, but IIRC they gave up.  In the Waterpan Village of the mine, a small sinkhole opened up in a street and swallowed part of a house (no one hurt or killed).

There is also a very large fault running north-south which cuts a small tar road in that area.  It displaces the road vertically by a few centimetres.  What makes this noteworthy is that this fault has been mapped with seismic surveys and it cuts through both the Karoo rocks and Wits rocks, but with diferent amounts of displacement.  Basically what that means is that this fault was already there when the Karoo rocks were deposited some 300 million years ago, and it is still active.  The Earth is a many splendoured thing...
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Offline LeonDude

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Re: Caving anybody? Check this out!
« Reply #41 on: February 27, 2013, 04:09:32 pm »
Cool, thanks!  :thumleft:
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Offline Cave Girl

Re: Caving anybody? Check this out!
« Reply #42 on: March 06, 2013, 05:48:30 am »
So we going back this weekend to try finish off the cave survey if anyone is keen to join let me know. Climbing and rope work experience is necessary!  :)
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Offline White Rhino

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Re: Caving anybody? Check this out!
« Reply #43 on: March 06, 2013, 06:01:13 am »
Not so far, and I don't expect them to find any either because of the amount of mining activity in the area.


The mines have to dewater the general area in which they operate, to prevent the mines from flooding.  Most of the surrounding water is stored in the dolomites.  The mines on the West Rand have to pump this water from one compartment to another, because Rand Water Board needs the water for greater Jozi.  A "compartment" is a block of porous dolomite that is "sealed off" by relatively impervious dolerite dykes.  When a snot-nosed geo I had to map these things so that the mines and Rand Water could settle who was stealing whose water...

As the rocks surrounding the mines are dewatered, the water level goes down and these caves (which were filled with water) become dry.  Without the water pressure to help support the caves, they start to collapse.  Sometimes the collapsing area forms a chimney that continues to collapse until it reaches the surface - bingo! sinkhole.

That hilly area near Westonaria (near the old "North Shaft" of Western Areas Gold Mine) has a few sinkholes in it, where the softer Karoo sediments have aided the collapsing roof of caves.  There was one that the mine tried to fill with waste rock, but IIRC they gave up.  In the Waterpan Village of the mine, a small sinkhole opened up in a street and swallowed part of a house (no one hurt or killed).

There is also a very large fault running north-south which cuts a small tar road in that area.  It displaces the road vertically by a few centimetres.  What makes this noteworthy is that this fault has been mapped with seismic surveys and it cuts through both the Karoo rocks and Wits rocks, but with diferent amounts of displacement.  Basically what that means is that this fault was already there when the Karoo rocks were deposited some 300 million years ago, and it is still active.  The Earth is a many splendoured thing...
Interesting .... are you suggesting that the "cave" connects to a mine shaft?
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Offline Cave Girl

Re: Caving anybody? Check this out!
« Reply #44 on: March 06, 2013, 09:47:31 am »
Probably not  :( but there were 2 passages we could not get into without extra equipment

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Offline H2O

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Re: Caving anybody? Check this out!
« Reply #45 on: March 06, 2013, 10:53:50 am »
Itís been a while since Iíve had time to do any kind of report, but on 19 January we re - visited a sinkhole that is so amazing that I just have to tell you about it.
This sinkhole formed about 15 years ago to the south of Joburg, and only one person had ever been lowered down it. Back then, the farmer awoke one night from a thundering sound like an explosion. Upon investigating the next morning, they found that the corn field had a gaping hole in it.

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Offline LeonDude

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Re: Caving anybody? Check this out!
« Reply #46 on: March 06, 2013, 12:12:44 pm »
H2O, that is part of the reason why he allows us on his land, he would like to know what's going on down there.
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Offline Renier

Re: Caving anybody? Check this out!
« Reply #47 on: March 06, 2013, 12:59:48 pm »
very cool! looking forward to the rest!
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Offline Cave Girl

Re: Caving anybody? Check this out!
« Reply #48 on: March 11, 2013, 04:49:30 pm »
Just a quick update. We went back and spent the weekend at the cave - I didn't go down on Saturday as we needed a caver above ground and none else was around - I also wanted to try capture some photo's of the bats - alas the bats came out to late for my camera to get any real pic's - managed to capture one of the bats and confirmed it was a  Natal bent wing / Schreibers' long-fingered bat,  (Miniopterus schreibersii)
The guys pushed "bat passage" which took most the day - then headed back to the main passage to bolt the wall - having to carry quite a bit of equipment it was slow going. They only got out the cave after 7pm with LD doing a super human task of hauling the first person out almost single handed although I like to think I helped a bit. Sitting round the camp fire in the evening we were updated on the events - Gerrie found 2 really stunning formations and didn't have a camera so no photo's  :( he then had to leave early on Sunday so could not take us back to the "spot" to take photo's and I didn't find them on Sunday  :'(
We were also informed that the cave is actually on mine land and not private land. Officially it is SA's deepest dry cave recorded - so a really great find!
Sunday I went down but spent most the day rechecking the survey as there were a few ? that needed corrections. Came up early. The rest of the guys went through to the back and managed to put in 5 bolts - still about 3 or 4 short to reach the passage - so lots more work  :)
I am sure LD will post about his Geology lesson he was able to get out of Pedro  :thumleft:
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Offline LeonDude

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Re: Caving anybody? Check this out!
« Reply #49 on: March 12, 2013, 05:55:28 pm »
Actually, this weekend was more work than play for the cavers. One team was busy mapping the cave while another team was bolting the wall that leads up to the passage that they still havenít been able to get to. According to the team doing the bolting itís slow going because the wall is very soft.
As for the geology lesson, Iím not sure what I can tell you without boring the pants of most people, so Iíll just tell you about a new type of rock Iíve learned this weekend called Fubarolite. That is rock that has been Fucked Up Beyond All Recognition Ė olite. It is amazing what the Vredeford event did to some of the rocks in that area.
We did investigate some of the other holes and in one of the holes we could clearly see two cave entrances leading off. While we were there a small owl noticed us and promptly flew into one of the caves. I will let you guys know if we ever get a chance to explore that cave.
Some piccies to follow.
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Offline LeonDude

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Re: Caving anybody? Check this out!
« Reply #50 on: March 12, 2013, 06:07:02 pm »
Ok, here is the pics. The first 3 shows the hole with the caves I mentioned. These are brand new caves, never explored before.
This hole is not as deep as the one we are busy at, it's only about 20 meters deep. Ok, that is still lots of scary.
The last photo is of a crack that has opened up in a field. The goelogist agreed that this is probably going to become a sinkhole in the near future. I hope I'm not anywhere near when it does. But walking around there, you know that there are scary holes just waiting to open up beneath you. Just so you know how deep that crack is - Gerrie is more than 2 meters tall, he is a giant.
You tread carefully.  :biggrin:
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Offline Cave Girl

Re: Caving anybody? Check this out!
« Reply #51 on: March 14, 2013, 05:30:26 pm »
They are going back on Saturday to go check out the other sink holes and possible caves and I can't go  :'(
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Offline cloudgazer

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Re: Caving anybody? Check this out!
« Reply #52 on: March 14, 2013, 05:42:47 pm »
wow - interesting thread.
 

Offline EssBee

Re: Caving anybody? Check this out!
« Reply #53 on: April 02, 2013, 10:40:24 am »
Very interesting! Thanks all!  :biggrin:
 

Offline krazy-eyes

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Re: Caving anybody? Check this out!
« Reply #54 on: April 02, 2013, 12:13:06 pm »
They are going back on Saturday to go check out the other sink holes and possible caves and I can't go  :'(

yus! i want to go!
 

Offline Cave Girl

Re: Caving anybody? Check this out!
« Reply #55 on: April 02, 2013, 02:32:03 pm »
The caving club is offering a SRT training day on April 13th with a trip to the cave on the 14th April - Cost for no-non caving club members is R70.00 and includes a meal - if you are interested payment needs to be made by Monday next week (15th) - PM me for bank details etc if you interested.
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Offline THROTTLE JOCKEY

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Re: Caving anybody? Check this out!
« Reply #56 on: April 17, 2014, 03:08:03 pm »
 :sip:
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Offline plonker

Re: Caving anybody? Check this out!
« Reply #57 on: December 01, 2014, 05:25:56 pm »
Hi CG have there been any more developments at his sink hole/cave of recent times.
 

Offline OomD

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Re: Caving anybody? Check this out!
« Reply #58 on: December 01, 2014, 06:00:46 pm »
Found this thread now, wow impressive. Yeah, any updates? And, isn't caving also called spelunking?
 

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Re: Caving anybody? Check this out!
« Reply #59 on: December 01, 2014, 06:51:51 pm »
Yes, Caving is called spelunking, and yes, the cave has been explored further, but I will leave it to Cave Girl to give us an update.
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