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Author Topic:   The Story in the Rocks - Southwestern U.S.
Tanypteryx
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Posts: 3340
From: Oregon, USA
Joined: 08-27-2006
Member Rating: 3.5


Message 16 of 121 (779341)
03-03-2016 2:54 PM
Reply to: Message 15 by Dr Adequate
03-03-2016 12:30 PM


He said that sandstone could be produced by compaction alone, and adduced the fact that cannonballs shot at sandbags produced sandstone where they impacted. I've not seen this repeated anywhere else, I'd be interested to know if there is any sandstone anywhere that was lithified just by compaction.

I thought the process that forms sandstone is as much a chemical process that forms a binding matrix as it is a physical process that applies a force to compact the sand.

I wonder how much force it would take to compact sand into stone without melting it?

I would think that modern explosives apply more force per area than a cannon shot. Bombing ranges all over Nevada should have noticeable evidence if compaction alone causes sandstone to form.


What if Eleanor Roosevelt had wings? -- Monty Python

One important characteristic of a theory is that is has survived repeated attempts to falsify it. Contrary to your understanding, all available evidence confirms it. --Subbie

If evolution is shown to be false, it will be at the hands of things that are true, not made up. --percy


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Dr Adequate
Member (Idle past 320 days)
Posts: 16112
Joined: 07-20-2006


Message 17 of 121 (779349)
03-03-2016 4:07 PM
Reply to: Message 16 by Tanypteryx
03-03-2016 2:54 PM


I thought the process that forms sandstone is as much a chemical process that forms a binding matrix ...

Yeah, normally it's cemented, with, as edge says, carbonates, or (IIRC) with iron oxides. But Mantell seemed to think it could just be compacted. If anyone knows of an instance of this happening in nature rather than bombing ranges, let me know. Thanks.

Edited by Dr Adequate, : No reason given.


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edge
Member (Idle past 974 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


(1)
Message 18 of 121 (779350)
03-03-2016 4:11 PM
Reply to: Message 16 by Tanypteryx
03-03-2016 2:54 PM


I thought the process that forms sandstone is as much a chemical process that forms a binding matrix as it is a physical process that applies a force to compact the sand.

It depends on your definition of 'rock'. But in general, yes, it takes some kind of binding material. However, I can imagine pressures high enough to begin melding like grains together. Sometimes you can get sand to cohere with just a little bit of surface tension from moisture, though I wouldn't really call that 'rock'.

If you google 'compressed sand' you can get some idea of how they make some building material and art media. However, in most cases, I think they still use some kind of a binder.

quote:
I wonder how much force it would take to compact sand into stone without melting it?

No idea.

quote:
I would think that modern explosives apply more force per area than a cannon shot. Bombing ranges all over Nevada should have noticeable evidence if compaction alone causes sandstone to form.

Well, if you had a pure sand deposit that might work. Problem is that most of the dirt out there has clay and organic material in it; and it's not exactly a controlled situation.

Let's just say that it's a process, and has several contributing factors such as time, heat, solutions and compression.

I can say that the Jurassic rocks are not that lithified compared to older rocks, but are somewhat more so than younger rocks. Some late Mesozoic sandstone and younger can be gouged with a fingernail, even in pristine samples.

Here is one of my favorite pictures of the Entrada Fromation on the north end of the Uncompahgre Uplift.

This is the Slick Rock member and just above it in the distance are the very flat beds called the 'board beds'. And above that is the Wanakah Formation, a series of mudstone and sandstone. The Entrada is an aquifer and also contains many of the uranium deposits in the area.


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Faith 
Suspended Member (Idle past 713 days)
Posts: 35298
From: Nevada, USA
Joined: 10-06-2001


Message 19 of 121 (779352)
03-03-2016 4:13 PM


As for bombing ranges in Nevada, I understand that the underground caverns formed by the underground nuclear tests of a few decades ago are lined with thick glass, a later stage of what happens to sand under heat and pressure, yes?

Edited by Faith, : No reason given.


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NoNukes
Inactive Member


Message 20 of 121 (779356)
03-03-2016 4:22 PM
Reply to: Message 19 by Faith
03-03-2016 4:13 PM


a later stage of what happens to sand under heat and pressure, yes?

I would expect the formation of glass to be immediate. As soon as fused sand cools, there would be glass. Molten sand is essentially molten glass.


Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)

History will have to record that the greatest tragedy of this period of social transition was not the strident clamor of the bad people, but the appalling silence of the good people. Martin Luther King

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Dr Adequate
Member (Idle past 320 days)
Posts: 16112
Joined: 07-20-2006


(1)
Message 21 of 121 (779357)
03-03-2016 4:24 PM
Reply to: Message 19 by Faith
03-03-2016 4:13 PM


As for bombing ranges in Nevada, I understand that the underground caverns formed by the underground nuclear tests of a few decades ago are lined with thick glass, a later stage of what happens to sand under heat and pressure, yes?

Well normally if sand was subjected to both heat and pressure, it would be as a result of being deep underground, and in these circumstances it would cool slowly and give us the crystalline metamorphic rock quartzite. Glass, you will recall, is what you get when molten rock cools quickly, so that there's no time for crystallization.


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edge
Member (Idle past 974 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


(1)
Message 22 of 121 (779358)
03-03-2016 4:32 PM
Reply to: Message 21 by Dr Adequate
03-03-2016 4:24 PM


At any rate, it seems difficult to produce rock from pure sand simply by pressure until we reach pretty massive loads, and it is an ongoing process that takes time.

That is one reason why younger rocks are noticeably softer and recognizable as being younger in the field. Again, the rocks do talk.


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Faith 
Suspended Member (Idle past 713 days)
Posts: 35298
From: Nevada, USA
Joined: 10-06-2001


Message 23 of 121 (779365)
03-03-2016 5:10 PM
Reply to: Message 22 by edge
03-03-2016 4:32 PM


That is one reason why younger rocks are noticeably softer and recognizable as being younger in the field.

Maybe, or perhaps they simply did not undergo the pressure and compaction of harder rocks.

Again, the rocks do talk.

But sometimes they don't speak English, or you don't hear them right.


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Tanypteryx
Member
Posts: 3340
From: Oregon, USA
Joined: 08-27-2006
Member Rating: 3.5


Message 24 of 121 (779366)
03-03-2016 5:12 PM
Reply to: Message 18 by edge
03-03-2016 4:11 PM


Here is one of my favorite pictures of the Entrada Formation on the north end of the Uncompahgre Uplift.

And above that is the Wanakah Formation, a series of mudstone and sandstone. The Entrada is an aquifer and also contains many of the uranium deposits in the area.

That is a sweet shot. Is Mesa Vere a part of the same formation? It looks similar.

Do you know, is the uranium associated with zircon crystals or sand? The reason I ask is, for years I worked in the analytical lab of a zirconium refinery and one of the byproducts of extracting zirconium from zircon sand was uranium that had to be disposed of at a facility at the Hanford Nuclear reservation. I guess what I'm asking is what minerals contain the uranium?


What if Eleanor Roosevelt had wings? -- Monty Python

One important characteristic of a theory is that is has survived repeated attempts to falsify it. Contrary to your understanding, all available evidence confirms it. --Subbie

If evolution is shown to be false, it will be at the hands of things that are true, not made up. --percy


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Tanypteryx
Member
Posts: 3340
From: Oregon, USA
Joined: 08-27-2006
Member Rating: 3.5


(4)
Message 25 of 121 (779387)
03-03-2016 7:50 PM


Back tracking a bit
I am still sorting through images and thought this one shows some cool looking strata. I think this is called Mt. Jackson Ridge. It is just north of Hwy 266 near the junction with Hwy 95 south of Goldfield Nevada.

I like vertical layers of strata that are now exposed to erosion.

We had just come from Deep Springs Valley to the west, where there was also a lot of tortured landscape and exposed quartzite. In the distance you can see the White Mountains, where some of the ancient Bristle Cone Pines, Pinus longaeva, are found. Above those are the tops of the Sierras. The green patch to the left of center is Deep Springs Ranch which is also the private Deep Springs College.

This is looking south toward the dry alkali lake that you can barely see in the above shot. The vegetation where I am standing is lush because there is a small spring with water flowing in a stream for about 0.5 kilometers before disappearing. This is extreme desert at about 6,000 ft elevation. It is about 25 miles north of Death Valley.

The reason I visit this spot is to photograph one of the rarest dragonflies in the world. Cordulegaster deserticola is only known from 3 close springs in the area.

Notice how I managed to slip a mention of dragonflies into the discussion?


What if Eleanor Roosevelt had wings? -- Monty Python

One important characteristic of a theory is that is has survived repeated attempts to falsify it. Contrary to your understanding, all available evidence confirms it. --Subbie

If evolution is shown to be false, it will be at the hands of things that are true, not made up. --percy


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edge
Member (Idle past 974 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


(1)
Message 26 of 121 (779388)
03-03-2016 8:00 PM
Reply to: Message 24 by Tanypteryx
03-03-2016 5:12 PM


That is a sweet shot. Is Mesa Vere a part of the same formation? It looks similar.

Actually, that is the Mesa Verde Supergroup formation know locally as the Cliff House Formation. It is quite a bit younger, late Cretaceous.

http://www.nps.gov/meve/planyourvisit/upload/geology_web.pdf

Do you know, is the uranium associated with zircon crystals or sand? The reason I ask is, for years I worked in the analytical lab of a zirconium refinery and one of the byproducts of extracting zirconium from zircon sand was uranium that had to be disposed of at a facility at the Hanford Nuclear reservation. I guess what I'm asking is what minerals contain the uranium?

The uranium comes in from elsewhere basically in groundwater that has passed through weathering igneous rocks.

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edge
Member (Idle past 974 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 27 of 121 (779539)
03-05-2016 12:54 PM
Reply to: Message 25 by Tanypteryx
03-03-2016 7:50 PM


Re: Back tracking a bit
This is looking south toward the dry alkali lake that you can barely see in the above shot. The vegetation where I am standing is lush because there is a small spring with water flowing in a stream for about 0.5 kilometers before disappearing. This is extreme desert at about 6,000 ft elevation. It is about 25 miles north of Death Valley.

Tall sage...

Hate the stuff.


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Tanypteryx
Member
Posts: 3340
From: Oregon, USA
Joined: 08-27-2006
Member Rating: 3.5


Message 28 of 121 (779562)
03-05-2016 7:12 PM
Reply to: Message 27 by edge
03-05-2016 12:54 PM


Re: Back tracking a bit
Tall sage...
Hate the stuff.

Sometimes I do too. At this spot, Antelope Springs, though, on hot days the dragonflies hang up on the shady side of the sage and sometimes I can get close enough to photograph them. This species is really wary, so they are a challenge.


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Tanypteryx
Member
Posts: 3340
From: Oregon, USA
Joined: 08-27-2006
Member Rating: 3.5


Message 29 of 121 (779563)
03-05-2016 7:29 PM
Reply to: Message 14 by edge
03-03-2016 11:33 AM


Hematite Nodules?
Somewhere I read about hematite (Fe2O3) nodules forming in sandstone that contains iron. I have not been able to find the source where I got that.

Could these black rocks be examples of that? This is the Navajo Sandstone in Snow Canyon, Utah again.

There are volcanic rocks overlying the sandstone close by so that may be what we can see here.


What if Eleanor Roosevelt had wings? -- Monty Python

One important characteristic of a theory is that is has survived repeated attempts to falsify it. Contrary to your understanding, all available evidence confirms it. --Subbie

If evolution is shown to be false, it will be at the hands of things that are true, not made up. --percy


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edge
Member (Idle past 974 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


(1)
Message 30 of 121 (779565)
03-05-2016 8:17 PM
Reply to: Message 29 by Tanypteryx
03-05-2016 7:29 PM


Re: Hematite Nodules?
Somewhere I read about hematite (Fe2O3) nodules forming in sandstone that contains iron. I have not been able to find the source where I got that.

Could these black rocks be examples of that? This is the Navajo Sandstone in Snow Canyon, Utah again.

There are volcanic rocks overlying the sandstone close by so that may be what we can see here.


The rocks look like basalt and are pretty clearly transported. Not sure how, but they came from somewhere else.

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