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27-Aug-2012 9:31:20 AM
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A question for geologists...
I've been developing a cliff out at New Nowra call Sunshine Sunnyside these past few years that features bizarre white smooth pockets that are very reminiscent of limestone (the underlying rock is sandstone). In fact the base of the cliff has several poxy stalactites and tufa formations which have formed over the sandstone. These 'limestone' pockets seep after heavy rain - but even more bizarrely they seep salty water - and leave salt crystals all over the rock surface. I only discovered this when I was putting the rope in my mouth one day and it tasted salty. Being the amateur scientist I am I then proceeded to lick the rock - which in parts was incredibly delicious. In some places on the rock surface the salt is 1mm thick coating the surface in pure white crystal form. This crag is 30km inland so it's not from salt spray. Can anyone explain this phenomenon? And does salty rock mean that bolts will corrode much faster? I have noticed that some of my 304 grade stainless U-bolts are already rusting up a bit after 2 years.
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27-Aug-2012 9:37:48 AM
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When WM and Andrew Duckworth were putting up those couple of routes at the left end of PC at Nowra there were a couple of little caves a ways up the cliff that were chockful of salt (hence some of the route names). We never got to the bottom of it, but perhaps it's the same phenomenon?
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27-Aug-2012 9:41:34 AM
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On 27/08/2012 pmonks wrote:
>When WM and Andrew Duckworth were putting up those couple of routes at
>the left end of PC at Nowra there were a couple of little caves a ways
>up the cliff that were chockful of salt (hence some of the route names).
> We never got to the bottom of it, but perhaps it's the same phenomenon?
I obviously need to do the lick test on every Nowra crag.
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27-Aug-2012 9:49:02 AM
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The Rave Cave at Wingello is exactly the same rock. Its even more inland...
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27-Aug-2012 9:55:36 AM
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On 27/08/2012 BundyBear wrote:
>The Rave Cave at Wingello is exactly the same rock. Its even more inland...
But is it salty?
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27-Aug-2012 10:13:22 AM
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On 27/08/2012 nmonteith wrote:
>On 27/08/2012 BundyBear wrote:
>>The Rave Cave at Wingello is exactly the same rock. Its even more inland...
>
>But is it salty?
There is also a big poo... stalagmite type formation past super fun happy wall..it looks very much like something you would see in a cave system but the rock above is definitely sandstone....and no I haven't licked it.
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27-Aug-2012 10:18:45 AM
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On 27/08/2012 Cliff D wrote:
>OK. No geologist but from gradeschool science ... limestone is formed from
>deposits of skeletons of tiny sea creatures. Inland salt deposits can result
>from old ocean deposits. And much/most of Australia was under the ocean
>yonks ago.
There are a lot of fossilized shells in the rock around Nowra.
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27-Aug-2012 10:32:55 AM
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I've seen this up at Turinga falls too (and around other areas in Sydney), so it's not a localised phenomenon. Salt spray can get carried a surprising distance inland, although obviously not at the same rates as near the coast.
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27-Aug-2012 10:40:23 AM
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It's not salt spray - it's leeching from the rock. I imagine the limestone 'coating' over the sandstone is also formed by minerals dissolved into water leeching out of the porous rock for thousands of years. I've just never noticed the salt factor before - and it slightly alarms me regarding bolt lifespans. Wasn't some of the Thailand problems associated with high levels of salt in the rock itself?
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27-Aug-2012 10:46:40 AM
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Maybe not salt spray directly onto the surface - but sandstone is really quite porous, so spray that finds its way into the (also sandy) soil can quite easily be washed through the rock.
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27-Aug-2012 10:50:00 AM
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On 27/08/2012 wombly wrote:
>Maybe not salt spray directly onto the surface - but sandstone is really
>quite porous, so spray that finds its way into the (also sandy) soil can
>quite easily be washed through the rock.
That does make sense. Interesting thought... I wonder over what time period?
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27-Aug-2012 10:58:06 AM
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Just had a chat with my father the geologist. Was completely nonplussed. Says those kind of salty formations are pretty common. Says underground those crystals associated with a seep through a salty formation can become very large. Warns that it is probably not "sea salt." Probably Epsom salts and other less nice salts. Arsenic, antimony, and other heavy metal are also very common. Licking them might not be a good idea. Arsenic salts for example might taste good and when in solution are weak acids corroding things. Antimony salts might have a distinct metallic taste and would have lots of free chlorine ions floating about for your SCC. Keep in mind heavy metals accumulate in your fatty bits. Yum!
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27-Aug-2012 11:03:15 AM
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I thought most ground water was at least partially salty and that's why some bores in some aquifers aren't potable or suitable for irrigation? Maybe this rock is fault through a particularly salty aquifer system?
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27-Aug-2012 11:05:08 AM
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Sandstone is very porous, the water that seeps out also is resposible for forming these pockets through gradual erosion. This water will also contain any minerals that are found in the underlying rock.
As it is exposed to the atnosphere it the water evaporates leaving these minerals behind. Commonly calcium or salt are left as a residue. In this case salt is more likely due to the fact Sandstone is originally formed as deposited silt/sand layers on the bottom of the ocean before being compressed to form the stone it is now.
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27-Aug-2012 11:16:17 AM
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.... and for the pedants out there, rain water is also salty. Expressed in terms of electrical conductivity (EC - a standard measure of salinity), rainwater can be up to around 40EC.
By way of camparison, the town water in Nati (prior to the pipe line) was above 1300EC (that was as high as my salinity metre went), but did not taste salty. 800EC is considered to be good quality irrigation water, and 400EC WHO recommended limit for human consumption.
I'm of the opinion that Neil needs to continue licking various forms of rock, but needs to add some control licks into his methodology, for scientific authenticity. he should begin by licking other climbing related items. I understand that Simey isn't doing anything at the moment, so Neil should begin by licking simey, follwed by a selection of other people who have climbed a Nowra, to determine the reationship.
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27-Aug-2012 11:39:32 AM
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In terms of the taste test, sea salts (i.e. NaCl or your regular table salt) will generally taste salty, while calcium or magnesium ones (commonly from rock weathering) usually don't. Neil could extend his experiment in climber-licking to see if there's a difference between climbers who frequent Nowra vs those from the Blueys or Araps...
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27-Aug-2012 11:51:02 AM
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Up to the early 20th century, papers describing newly discovered/synthesised chemical compounds often listed "taste" amongst the description of physical properties!?!
I admire Neil's commitment to licking cliffs in the name of science.
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27-Aug-2012 12:03:06 PM
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Ingestion is de rigeur nowadays...
"in July 1984, Dr. Marshall decided to swallow a large number of the bacteria himself to test his ideas about H. pylori."
http://www.johnshopkinshealthalerts.com/reports/digestive_health/869-1.html
So munch down Neil and report back on "Arsenic as an essential micronutrient in the diet of strong climbers"
Apparently eating rocks is called lithophagia. Useless fact for the day
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27-Aug-2012 12:05:58 PM
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I've heard it helps to swallow some cement to harden up a bit .. Neil is just going straight to the source ..
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27-Aug-2012 12:08:00 PM
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>I admire Neil's commitment to licking cliffs in the name of science.
its just the logical progression after a childhood spent licking cane toads :)
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