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Author Topic:   Peanut gallery for Great Debate?
Percy
Member
Posts: 19411
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.7


Message 2 of 24 (197426)
04-07-2005 10:32 AM
Reply to: Message 1 by roxrkool
04-07-2005 10:26 AM


I'm all in favor. People don't usually sit on their hands during debates.

--Percy


This message is a reply to:
 Message 1 by roxrkool, posted 04-07-2005 10:26 AM roxrkool has not yet responded

Replies to this message:
 Message 3 by JonF, posted 04-07-2005 10:55 AM Percy has not yet responded

Percy
Member
Posts: 19411
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.7


Message 6 of 24 (197448)
04-07-2005 11:38 AM
Reply to: Message 5 by AdminJar
04-07-2005 11:11 AM


Re: I would hope that we would refrain
One of the rules of a Great Debate should be that the participants have to remain on stage, they can't go out and mingle with the audience.

Added by Edit: And moderators should maintain order in the peanut gallery. This isn't a place for cheap shots. Any Great Debater who feels they're being unfairly abused in the peanut gallery should appeal to the moderators.

--Percy

This message has been edited by Percy, 04-07-2005 10:42 AM


This message is a reply to:
 Message 5 by AdminJar, posted 04-07-2005 11:11 AM AdminJar has not yet responded

Percy
Member
Posts: 19411
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.7


Message 10 of 24 (197489)
04-07-2005 2:57 PM


Jazzns has just posted a response at Message 102, and I wanted to offer a clarification for this part:

Jaxxns writes:

When erosion happens that causes sediment to go away, that environment will not produce a sedimentary layer. This is what I meant when I said that in order to make a sedimentary rock you need the net effect to be deposition rather than erosion.

An example might make clear what Jazzns means by "erosion that causes sediment to go away." A mountainous region drained by rivers will be an area of net erosion. The mountains are worn down by weathering. The products of erosion accumulate in the valleys and eventually make it to the rivers and are carried downstream and out of the region. Mountainous regions are areas of net erosion.

When erosion happens that does not cause sediment to go away, that environment will produce a sedimentary layer. Environments where this will happen are low places like a basin. A canyon is not going to form at the bottom of a basin because rivers and other runoff do not go uphill.

In this case Jazzns explains "erosion that does not cause sediment to go away" with the example of a basin, but a little more can be said. On land, a basin is a local low-lying area. A basin from which all exits require going uphill could only accumulate sediments, excepting wind-borne mechanisms. All the products of weathering from surrounding higher areas would eventually find their way to the basin where they'll accumulate.

In reality, there is rarely anything like a perfect basin. Perfect basins are frequently lakes and ponds, since water cannot escape uphill. If the area is very dry then lakes and ponds won't form and there will more likely be sand. But most land basins are not perfect. They usually have sediments being both deposited and carried away.

A mountain valley is an excellent example of a local basin where sediments are both being deposited and carried away. Erosion carries the effects of weathering on the mountains into the valley where they deposit on the soil, gradually building up after millenia. If you could peer through the soil to the underlying rock you would find that in most cases the area between mountains is as jagged as the mountains themselves, but we can't see this because it is all covered over by soil and other deposits. Material has accumulated in the valleys between mountains because erosion is gradually carrying the mountains, particle by particle, onto the valley floor.

But most mountain valleys are drained by rivers, and so the ground and soil of the valley is gradually being carried downstream and eventually out to sea. If the river drainage carries sediments away faster than erosion of the mountains deposits them, the valley floor is gradually diminished (lowered, and of course narrowed as it lowers). If the reverse is the case then the valley floor will climb the mountain sides and become wider.

But feedback is built into this process. As the valley floor rises, the river flows from a higher height and therefore more vigorously carries sediments away. As the valley floor lowers, the river flows more slowly and carries fewer sediments away. The system is balanced between sedimentary inputs and outputs until the mountains are finally weathered and eroded away to the point where their input to the sedimentary process declines so much that the entire region begins to erode to lower and lower elevations.

Jazzns writes:

Faith writes:

You betcha. Water is the ONLY thing that will give us the horizontal layers.

No, low places where sediment accumulates gives us horizontal layers. We see this today. We also see this in the geologic column in sediments that cannot have been deposited by water. This is the reason I brought up the issue of sediments that are very much land deposits which has yet to be addressed.

It is important that anyone reading this explanation from Jazzns keep in mind his earlier very careful explanation that it is much more rare for land to be an area of net deposition. There can be areas of land which are true basins and from which all exits lead uphill, but this is merely local. The reality for most land throughout the world is that there is always someplace lower where the sediments will eventually end up: bodies of water. Almost all land deposits are temporary - their eventual fate is lining the bottoms of bodies of water. Back when the Coconino layer of the Grand Canyon was still above ground, had the area not subsided beneath the waves where it was covered and protected by sediments but had instead remained above sea level and exposed to weathering and erosion, the Coconino layer would eventually have eroded away and off into the sea, leaving nothing behind. Except a disconformity.

My compliments to both Faith and Jazzns for a debate refreshingly free of accusations and recriminations.

--Percy


Replies to this message:
 Message 11 by Jazzns, posted 04-07-2005 6:38 PM Percy has not yet responded

Percy
Member
Posts: 19411
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.7


Message 13 of 24 (197554)
04-07-2005 7:27 PM
Reply to: Message 12 by Adminnemooseus
04-07-2005 7:09 PM


Re: Adminnemooseus still says "No" to having a "Peanut Gallery" right now
Adminnemooseus writes:

In the context of , I think it is impossible to isolate the "Great Debate" from the "Peanut Gallery". Are we to expect that neither Jazzns or Faith will read the topic?

Is there a downside to their reading a Peanut Gallery topic for their debate? I think of it like an audience viewing a live debate. The reactions of the audience are apparent to the debaters. Having to refrain from commenting seems stilted and unnatural, like pretending nothing's going on when something really is. Great Debates take place infrequently, and it feels like they should be a happening kind of thing of great excitement and interest.

I agree with Jazzns's comment that contributions here should be circumspect. This isn't a place for people to take free potshots. And as I said earlier, I don't think Jazzns or Faith should post to this thread as it would distract their attention from the Great Debate.

--Percy


This message is a reply to:
 Message 12 by Adminnemooseus, posted 04-07-2005 7:09 PM Adminnemooseus has responded

Replies to this message:
 Message 14 by Adminnemooseus, posted 04-07-2005 7:42 PM Percy has responded

Percy
Member
Posts: 19411
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.7


Message 15 of 24 (197561)
04-07-2005 8:16 PM


Jazzns recently posted a couple replies to Faith (Message 104 and Message 105) that expressed uncertainty about how to answer. Understandng is often improved when things are explained in different ways, and I think I know what Faith is getting at.

In Faith's Message 105 in the first paragraph she provides her understanding of what Jazzns has been saying:

Faith writes:

Look, I have been talking about this for some time and you have been mostly addressing topics peripheral to it. Leave the Coconino for now and please address the formation of the other layers, as you and others have said that while they were formed as oceanic sea deposits there were also MANY risings and fallings of sea level and SOME of the layers had SOME length of time above water in which they were exposed to weather in an aerial environment, AND, if I got this right, that these periods out of water explain the erosion that IS seen between certain layers.

Just so there's no uncertainty, Faith is correct, in general that's what we believe the evidence indicates has happened.

Here's the first half of Faith's next paragraph:

Faith writes:

Please let's stick to this topic. This has to be established first. I've been guessing that those that were exposed to air after having been laid down as marine deposits would have been so exposed for AT LEAST a very conservative million years out of the 20 or 50 million given for the total formation of a given layer, and unless I missed it you haven't said one word about this guess. Was it a million or ten million and which layers were so exposed to the air?

I think Jazzns has answered this, but it doesn't hurt saying it again. In the absence of other evidence, it is impossible to say how much has been eroded away. A disconformity tells us that somewhere between a little and a whole bunch was eroded away. Determining exactly how much was eroded away by looking only at the disconformity would be like trying to tell the size of the original granite rock from which a statue was carved.

But there is evidence we can look at beyond the disconformity. The layers that were eroded away at the Grand Canyon because that region was pushed temporarily above the waves may not have been eroded away at some other location that wasn't pushed above sea level. The disconformity tells us that the bed of the ancient sea that used to exist at what is now the Grand Canyon was above sea level during some periods of time, but that doesn't mean all parts of that ancient sea were pushed above sea level at the same time. Some of the layers missing at the Grand Canyon site may still exist in other areas of the region, can we only find them.

Another more remote possibility for evidence is that the eroded layers may be redeposited elsewhere in a way that indicates their origin. For example, one way we know that the Appalachians used to be an enormous mountain range is because the products of erosion of these mountains are found in enormous amounts in adjacent regions.

But another possibility is that there may be no evidence to tell us how much was eroded away, and therefore nothing to tell us how long the region was exposed to the forces of weathering. All the disconformity tells us is that it happened. It doesn't tell us for how long it happened.

Faith writes:

What about the disconformities where it is believed that entire layers were eroded away? I've been mostly focused on this and have been claiming that during whatever time period it was, these layers would have been subjected to greater erosion than is present in any of them. This is what both my illustrations were designed to show. (As a matter of fact MANY things would have been different with such a scenario than what is actually observed but that's another subject).

I'm guessing that this is the part that most puzzled Jazzns about how to reply, but his replies indicate he believes Faith still misunderstands what effects weathering and erosion have on a landscape, and I think he's right.

I can't think of a better analogy than my earlier one of sandpaper. Sandpaper takes down the highest irregularities of wood first. In the same way, weathering affects to a greater degree the most exposed portions of a landscape, like mountains. The products of weathering are carried to the lowest points, like valleys. It would be as if the sawdust of sandpapering the highest points of rough wood became deposited firmly in the lower places in between. As Jazzns says, erosion tends to erode things flat, and deposition tends to pile things up flat.

There's another way in addition to erosion that mountains descend to the valleys. Anyone who lives in a hilly region has probably seen the occasional row of telephone poles climbing a grassy hillside. If the telephone poles have been there for a while then they're usually tilted downslope. That's because the topmost layers of earth are descending the mountain faster than the more compressed layers a few feet down. It's simple gravity. Gravity is the great leveler - everything seeks the lowest point. Any point that somehow builds up higher will gradually and eventually be dragged down level with the surrounding landscape through weathering and erosive processes.

But as Faith mentions, there *are* processes that can cut a landscape in irregular ways, and they're called rivers and streams. A river running across a landscape is like taking a saw to wood - it can make a deep cut, and unlike a saw, it can be very irregular. JonF has posted a number of images of rivers and canyons embedded in geological layers. Faith's deductions are correct, because the features she thinks should be found in geological layers *are* found in geological layers.

--Percy


Percy
Member
Posts: 19411
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.7


Message 16 of 24 (197563)
04-07-2005 8:23 PM
Reply to: Message 14 by Adminnemooseus
04-07-2005 7:42 PM


Re: Adminnemooseus still says "No" to having a "Peanut Gallery" right now
Adminnemooseus writes:

While a "real world" debate might have an audience, that audiences responses to statements would be limited to such as cheers and groans. They would not be shouting debate content up to the podiums.

True, but you're addressing the analogy, not the point I was making. The Internet is a much richer environment (in some ways) than the live debate before an audience, and there any many more channels of feedback available. I think what you're saying is that you believe some of that feedback affects the debate in material ways. I agree. Viva la differance!

--Percy


This message is a reply to:
 Message 14 by Adminnemooseus, posted 04-07-2005 7:42 PM Adminnemooseus has not yet responded

Replies to this message:
 Message 17 by Minnemooseus, posted 04-07-2005 9:39 PM Percy has responded

Percy
Member
Posts: 19411
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.7


Message 18 of 24 (197580)
04-07-2005 10:16 PM
Reply to: Message 17 by Minnemooseus
04-07-2005 9:39 PM


Re: Off topic grammar digression
minnemooseus writes:

So, I think feedback effects the debate. The change in the debate would be the affect. :)

Let's ask Al Frankin! :)

Recently it was pointed out to me that "effect" is a verb, and "affect" is a noun.

Both are both. An actor might try to effect an impression of heightened affect, and that might affect the audience with great effect.

--Percy


This message is a reply to:
 Message 17 by Minnemooseus, posted 04-07-2005 9:39 PM Minnemooseus has not yet responded

Percy
Member
Posts: 19411
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.7


Message 20 of 24 (198890)
04-13-2005 7:48 AM
Reply to: Message 19 by roxrkool
04-13-2005 12:56 AM


Re: GD topic much too broad...
One suggestion I think you made recently to Faith was to take her time. Unless Faith says she's done, it might be too early to conclude she's done.

--Percy


This message is a reply to:
 Message 19 by roxrkool, posted 04-13-2005 12:56 AM roxrkool has responded

Replies to this message:
 Message 21 by roxrkool, posted 04-13-2005 11:55 AM Percy has responded

Percy
Member
Posts: 19411
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.7


Message 22 of 24 (198953)
04-13-2005 11:59 AM
Reply to: Message 21 by roxrkool
04-13-2005 11:55 AM


Re: GD topic much too broad...
From Faith's Message 106:

Faith writes:

But maybe I just need to calm down and come back later. I did have a direction I was trying to go in, but I don't know if I can get back to it.

Doesn't sound like finality to me.

--Percy


This message is a reply to:
 Message 21 by roxrkool, posted 04-13-2005 11:55 AM roxrkool has responded

Replies to this message:
 Message 23 by roxrkool, posted 04-13-2005 2:53 PM Percy has not yet responded

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