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Sandstone after the rain
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Partner cracklover


May 24, 2009, 9:06 AM
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Sandstone after the rain  (North_America: United_States: Colorado: Boulder_Area: Eldorado_Canyon)
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Quick question - I know desert sandstone isn't safe to climb on after a heavy rain. Is this also true for Eldo?

GO


Partner angry


May 24, 2009, 9:45 AM
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Re: [cracklover] Sandstone after the rain [In reply to]
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I think it's fine personally. I don't know this but that's what I do.


PigsOnDrugs


May 24, 2009, 9:54 AM
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Re: [cracklover] Sandstone after the rain [In reply to]
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ive had times were you could press your hand after heavy rain into the sandstone and your handprint would now be there so just a heads up
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churningindawake


May 24, 2009, 9:56 AM
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Re: [PigsOnDrugs] Sandstone after the rain [In reply to]
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PigsOnDrugs wrote:
ive had times were you could press your hand after heavy rain into the sandstone and your handprint would now be there so just a heads up
In reply to:
I would personally stay off it for a little while.


Partner angry


May 24, 2009, 10:02 AM
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Re: [churningindawake] Sandstone after the rain [In reply to]
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Have either of you cheesetitters ever been to Eldo. The rock is harder and more dense than most granite.

It's technically sandstone but it's worlds apart from all other sandstone I've ever seen.

I really think the biggest worry is choss dislodged by the rain.


churningindawake


May 24, 2009, 10:24 AM
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Partner angry


May 24, 2009, 10:27 AM
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Re: [churningindawake] Sandstone after the rain [In reply to]
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churningindawake wrote:
angry wrote:
Have either of you cheesetitters ever been to Eldo. The rock is harder and more dense than most granite.

It's technically sandstone but it's worlds apart from all other sandstone I've ever seen.

I really think the biggest worry is choss dislodged by the rain.
I know that its harder. But it could be pretty slick.

n00b


sungam


May 24, 2009, 10:41 AM
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Sandstone after the rain [In reply to]
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Man I was hungry, but all those roflcakes sure hit the spot.
That's it wolfenstien - you tell John about colorado rock!


Partner cracklover


May 24, 2009, 1:52 PM
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Re: [angry] Sandstone after the rain [In reply to]
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angry wrote:
Have either of you cheesetitters ever been to Eldo. The rock is harder and more dense than most granite.

It's technically sandstone but it's worlds apart from all other sandstone I've ever seen.

I really think the biggest worry is choss dislodged by the rain.

It's the hardest sandstone I've ever been on, which is why I asked.

So far that's one vote for "not sure, but I think it's not a problem" and two votes for "I actually don't know what you're talking about, but I'll give an opinion anyway."

GUnsure


subantz


May 24, 2009, 5:01 PM
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Re: [cracklover] Sandstone after the rain [In reply to]
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When I was at Horse Pens 40, It had rained the night before. Before the comp. Adam Henry had a few things to say, One being that sandstone becomes weak after a rain. To be careful and not to use brushes even nylon brushes as after a rain it will scar the sandstone. Also holds are prone to break. Especially fragill little flaky crimps. I am not sure about Eldo but thats what there say here in the south.


altelis


May 24, 2009, 5:24 PM
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Re: [cracklover] Sandstone after the rain [In reply to]
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cracklover wrote:
angry wrote:
Have either of you cheesetitters ever been to Eldo. The rock is harder and more dense than most granite.

It's technically sandstone but it's worlds apart from all other sandstone I've ever seen.

I really think the biggest worry is choss dislodged by the rain.

It's the hardest sandstone I've ever been on, which is why I asked.

So far that's one vote for "not sure, but I think it's not a problem" and twoTHREE votes for "I actually don't know what you're talking about, but I'll give an opinion anyway."

GUnsure


jmeizis


May 24, 2009, 6:26 PM
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Re: [cracklover] Sandstone after the rain [In reply to]
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It's fine. If there was a sandstone equivelant for granite then this would be it. It's practically quartzite in both hardness and granular quality. The only reason it's not is because there was an ocean there as opposed to it forming underground with heat and pressure. Climb on.


desertwanderer81


May 24, 2009, 8:00 PM
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Re: [cracklover] Sandstone after the rain [In reply to]
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cracklover wrote:
Quick question - I know desert sandstone isn't safe to climb on after a heavy rain. Is this also true for Eldo?

GO

The reason why most sandstone is so dangerous to climb on is that the hydralic conductivity of the rock is very high and when saturated, it loses aprox 80% of its cohession.

The fact that Eldo sandstone is very hard to begin with is inmaterial. The real question is what is its hydralic conductivity. However due to our Colorado friend's answer, it sounds like it is quite low compared to most sandstone if he has been climbing on it after rain storms and there has been little or no rock breaking off.


desertwanderer81


May 24, 2009, 8:05 PM
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Re: [churningindawake] Sandstone after the rain by angry [In reply to]
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churningindawake wrote:
angry wrote:
Have either of you cheesetitters ever been to Eldo. The rock is harder and more dense than most granite.

It's technically sandstone but it's worlds apart from all other sandstone I've ever seen.

I really think the biggest worry is choss dislodged by the rain.
I know that its harder. But it could be pretty slick.

LOL, Funny stuff. Slick!!


sed


May 25, 2009, 9:58 PM
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Re: [cracklover] Sandstone after the rain [In reply to]
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Cohesion? Soil mechanics? Jesus the man asked a simple question and he gets words he'll need to google. Yes most sandstone is more dangerous to climb on when it's been raining but I refuse to let that fact penetrate my decision making. Here's some reasons why:
-wet sandstone is less sandy and therefore gets in my contact lenses less.
-bolts go into sandstone like it wants it.
-body parts bounce off sandstone better than dry sandstone.
-If you need a quick hold you can just scratch one with your fingernail.

So, as you can see, the friction and safety considerations don't matter much to me but I can't speak for you.Smile


desertwanderer81


May 27, 2009, 2:25 PM
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Re: [sed] Sandstone after the rain [In reply to]
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Yeah, basically the minerals which bind the sand together desolve in water :p


jmeizis


May 28, 2009, 8:49 AM
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Re: [desertwanderer81] Sandstone after the rain [In reply to]
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Is there an easy way to test hydralic conductivity? It'd be interesting to compare different types of sandstone.


desertwanderer81


May 28, 2009, 9:05 AM
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Ummm.....you need an aparatus where you can run water through the sample.... If you know what you're doing, and have about $300 bucks to blow, you could probably jury rig one together. Otherwise, you could find a soils lab....but they're going to charge probably more than you'd be interested in paying, hehe. Unless you can convince some college grad student to use their lab as part of a research project. You'd also have to have some way of making a core of the rock sample too....

You'd want them to run a falling head test:
http://en.wikipedia.org/wiki/Hydraulic_conductivity

Might be interesting to run unconfined compression tests on some dry and wet cores too! Those are much cheaper though ;)


camhead


May 28, 2009, 9:19 AM
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Re: [desertwanderer81] Sandstone after the rain [In reply to]
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so, hydraulic conductivity has nothing to do with the "hardness" of the rock?

All I'm going to say is this. Stay off softer sandstones after the rain. Southern Utah Desert, Redrocks, HP40 (as mentioned earlier), probably the Red River Gorge's vertical routes (although nobody ever does).

Harder sandstone such as the New River Gorge seems to be fine when soaked. I have not climbed that much in Eldo, so I will not comment on that.


desertwanderer81


May 28, 2009, 9:57 AM
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camhead wrote:
so, hydraulic conductivity has nothing to do with the "hardness" of the rock?

All I'm going to say is this. Stay off softer sandstones after the rain. Southern Utah Desert, Redrocks, HP40 (as mentioned earlier), probably the Red River Gorge's vertical routes (although nobody ever does).

Harder sandstone such as the New River Gorge seems to be fine when soaked. I have not climbed that much in Eldo, so I will not comment on that.

huh? I'm saying that this only has to do with the hardness of the rock after rain.... if the sandstone doesn't become saturated and the "binder" become desolved, then it won't lose strength.

And I agree with the rest of what you're saying, hehe.


camhead


May 28, 2009, 10:05 AM
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ok, sorry, I think I may have misunderstood you when you said--

desertwanderer81 wrote:

The fact that Eldo sandstone is very hard to begin with is inmaterial. The real question is what is its hydralic conductivity.

I assumed that you were saying that hardness and H.C. were unrelated. Whereas I took it to be that when a non-geologist such as myself talks about "hard" sandstone, it basically means "sandstone with low H.C." I suppose that in the end, the term "hard" simply does not work for what we are discussing.


desertwanderer81


May 28, 2009, 10:15 AM
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Re: [camhead] Sandstone after the rain [In reply to]
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camhead wrote:
ok, sorry, I think I may have misunderstood you when you said--

desertwanderer81 wrote:

The fact that Eldo sandstone is very hard to begin with is inmaterial. The real question is what is its hydralic conductivity.

I assumed that you were saying that hardness and H.C. were unrelated. Whereas I took it to be that when a non-geologist such as myself talks about "hard" sandstone, it basically means "sandstone with low H.C." I suppose that in the end, the term "hard" simply does not work for what we are discussing.

Well, say Sandstone A has an unconfined compression strength of 4,000 psi when dry. That same sandstone has an unconfined compression strength of 500 psi when saturated.

Now imaginary Sandstone B also has a strength of 4,000 psi while dry but since water doesn't go through it readily, it maintains that 4,000 psi even if submerged for a few days.

Honestly, there isn't much research on the topic. I am unsure if these harder sandstones have a higher strength after rain because they have minerals which do not disolve as readily or because they have a lower hydralic conductivity and therefor not saturated as quickly.

There does seam to be some correlation between the two though. Whether it is the cause or the effect, I really don't know.


desertwanderer81


May 20, 2010, 2:17 PM
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Re: [jmeizis] Sandstone after the rain [In reply to]
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http://www.aegweb.org/files/public/i1078-7275-15-1-29.pdf

Check this baby out! This is a fantastic paper which deals directly with the issue at hand.

According to this, the harder sandstones actually exhibit a GREATER loss of strength due to being saturated.


http://books.google.com/books?id=W7Svte0sBBoC&pg=PA103&lpg=PA103&dq=predicting+hydraulic+conductivity+of+sandstone&source=bl&ots=pvJ6yAUCu7&sig=qJdlhm8RX2VUVjiCAoBWc92n4Fw&hl=en&ei=y6T1S5maEY3wsgOq3rCIBQ&sa=X&oi=book_result&ct=result&resnum=6&ved=0CDYQ6AEwBQ#v=onepage&q=predicting%20hydraulic%20conductivity%20of%20sandstone&f=false
Correlations between hydraulic conductivity and other engineering properties for sandstone.

http://www.aqtesolv.com/forum/properties.htm
Ranges in hydraulic conductivities for Sandstone range from 3x10-10 to 6x10-6 m/s, obviously would be the controlling factor. If it's not saturated, it's not going to lose its strength.


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