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Author Topic:   Growing the Geologic Column
edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


(1)
Message 225 of 740 (734264)
07-27-2014 4:19 PM
Reply to: Message 223 by Faith
07-27-2014 3:45 PM


Are you saying that all these layers are volcanic ash or welded tuff?
The ones so-labeled are. In the bottom picture the whole outcrop is what we call a single 'cooling unit' or the product of a single eruption. If it is thick enough, the interior remains semi-molten and forms a glass such as obsidian. The word 'vitrophyre' means that it is a glass with some crystals in it.
And, what that would mean is that it was airborne rather than a flow, right?
Yes, but it did flow, though maybe not very far. Think of it like a turbidite similar to the ones we see in sedimentary rocks, just occurring in the atmosphere instead of the ocean. Ash flows are quite dangerous and kill a lot of people because they can outrun a vehicle.

This message is a reply to:
 Message 223 by Faith, posted 07-27-2014 3:45 PM Faith has replied

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edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 231 of 740 (734270)
07-27-2014 4:40 PM
Reply to: Message 229 by Faith
07-27-2014 4:31 PM


Re: Layer / Sill
But basalt IS usually intrusive into sedimentary rock, occurring as dikes and sills.
You would call the Columbia River Basalts what? Intrusives?

This message is a reply to:
 Message 229 by Faith, posted 07-27-2014 4:31 PM Faith has replied

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edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 236 of 740 (734275)
07-27-2014 4:48 PM
Reply to: Message 230 by Faith
07-27-2014 4:38 PM


Re: Blackrock Escarpment is all volcanic
The thing is, that Cardenas lava between the layers looks SO layer-like in the diagram,...
Actually, it isn't. Usually, volcanic rocks have a more limited areal extent, so at the edges of the outcrop area, it goes to zero thickness. And remember it is a diagram.
... so evenly thick, not lumpy enough to be a lava that would have flowed over a surface and later been covered by another sediment. I mean, lava usually IS pretty lumpy as it hardens on the ground, isn't it? (I keep meaning to get back to Percy's post about that.)
When freshly deposited, yes. However, that would not be visible at this scale and ,as the article stated, the surface is weathered and eroded anyway, so it's a moot point.

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edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 241 of 740 (734283)
07-27-2014 5:07 PM
Reply to: Message 239 by Faith
07-27-2014 5:04 PM


Re: Blackrock Escarpment is all volcanic
I'm sorry, I don't see how that has anything to do with the question about the Cardenas basalt.
It shows ways of contrasting intrusive with extrusive igneous rocks. The Cardenas Basalt looks essentially like the diagram.
Edited by edge, : No reason given.

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 Message 239 by Faith, posted 07-27-2014 5:04 PM Faith has replied

Replies to this message:
 Message 258 by Faith, posted 07-27-2014 11:07 PM edge has replied

  
edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


(1)
Message 247 of 740 (734290)
07-27-2014 5:31 PM
Reply to: Message 244 by Faith
07-27-2014 5:16 PM


Re: Layer / Sill
According to Old Earth assumptions, ...
I have yet to be shown that the supported assumption of an old earth is wrong. Perhaps you can do that?
... but they are just assumptions, ...
Well-supported assumptions.
... something you take for granted, ...
Not at all. I agree that some processes are rapid.
... but if a worldwide Flood DID occur that would provide the very situation of changing sea levels where Walther's Law operates, but much faster.
Actually, the law would be in effect, but there would be vanishingly little time to produce a record.
In the case of the Flood it took about five months for the level to rise to its fullest height and after it had stayed at its height for a month or two it took another five months to regress.
Not enough time to create the deposits that we find. Where did the sediments come from? How did dinosaur tracks form in the middle of the fludde? Where did evaporites come from?
Why are these questions radioactive to YECs?
Plenty of time to deposit all those sediments the forty days and nights of heavy rain had dumped into the rising water.
Please show what rocks eroded to provide the sediments in 40 days.
Yes, that's the idea. And so much the more if the Pacific wandered up to meet the Atlantic in the Midwest.
If, if, if...
Please provide evidence of such a fludde.

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edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 248 of 740 (734291)
07-27-2014 5:36 PM
Reply to: Message 246 by herebedragons
07-27-2014 5:31 PM


Re: Layer / Sill
I guess its just that to someone who doesn't study these things a lot, it can be hard to see the kind of processes that will someday, maybe, become rock. Its like looking at a still of a movie and trying to figure out the plot. I too see the same processes at work today that formed the features of the past. However, I can see how someone like Faith would see it as strangely different. It does take some research to understand it.
It's hard sometime to wrap your mind around geological concepts. To me, a Mesozoic rock looks different from a Paleozoic rock, different from a Proterozoic rock. I can imagine someone trying to figure out how a modern stream channel gets incorporated into the geological record; keeping mind that all we really are familiar with is terrestrial processes. I think if you see a lot of rocks with similar depositional environments from various ages, it becomes easier.

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edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 252 of 740 (734296)
07-27-2014 5:57 PM
Reply to: Message 249 by herebedragons
07-27-2014 5:43 PM


Re: Layer / Sill
You're probably right, but most stratigraphic sections I have found only identify them as "basalt" which Faith simply dismisses as intrusive. Just like I presented 4 sections with clear lava layers between sedimentary layers and what I get is "basalt IS usually intrusive into sedimentary rock,"
I would say that the term 'basalt' generally refers to an extrusive igneous rock, unless qualified or otherwise determined by context.
A coarse-grained basaltic (composition) rock would be called a gabbro, so many dikes are actually gabbro. These are almost certainly intrusive in character. I know of no extrusive gabbros, or granites.
In a way it is unfortunate that geology is such an old science that there are many archaic terms, and casually used words, along with words derived from a variety of languages just to confuse things. However, it makes for a rich history and colorful language, just takes a long time to master it.
ETA: I should add that 'basalt' definitely refers to a fine-grained rock.
Grrrr.
Being casually dismissed is a sure insult.
Edited by edge, : No reason given.

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 Message 249 by herebedragons, posted 07-27-2014 5:43 PM herebedragons has replied

Replies to this message:
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edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 254 of 740 (734298)
07-27-2014 6:12 PM
Reply to: Message 250 by Minnemooseus
07-27-2014 5:52 PM


Re: Layer / Sill
I'm reading a fair amount of "Yes, but.." material from the evo side.
I think this comes from trying to provide a textbook in piecemeal fashion. And most of the discrepancies are really not relevant to the actual discussion being driven by Faith's strange understanding of geological evidence.

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edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 263 of 740 (734308)
07-28-2014 1:16 AM
Reply to: Message 257 by herebedragons
07-27-2014 9:41 PM


Re: Layer / Sill
Based on your and Moose's comments, I may have put the cart before the horse. It seems a basalt is a basalt because it is fine grained (plus the chemical composition part) not just because it is extrusive. However, it is fine grained because it cools rapidly which is indicative of an extrusion. That about right?
Yes. The term 'basalt' has certiain implications, both textural and compositional.
I do think Percy makes a good point that usage on the internet is not consistent and the term basalt is used for intrusions. I don't think I have seen the term gabbro used on a generalized cross section at all. So without more information, it is pretty difficult to be completely convincing that it is extrusive.
It's all a function of cooling history. If a dike cools quickly, it could be a basalt. Usually this will happen at the surface or near the surface since that is where the cooler environments are.
However, I don't see how tuffs or ash flows could be intrusions nor occur underwater, so they should be sufficient to establish a break in continuous sedimentation (during a flood).
Correct. In general. Tuffs can be water lain if they occur over a lake, for instance. I have seen ash flows which probably covered a shallow lake or swamp. It gets really interesting...

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edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


(1)
Message 265 of 740 (734310)
07-28-2014 1:29 AM
Reply to: Message 258 by Faith
07-27-2014 11:07 PM


Re: Cardenas basalt
But what it shows is a dike up through the limestone, an intrusive event in other words, but you are saying the Cardenas is not an intrusive.
Maybe I can clarify. The lava flows are definitely extrusive onto the surface of the earth. The thing is that they have to come from somewhere. We often call those sources 'feeders' or vents. Those would be very close to the surface, yet intrusive.
Edited to add: I'm still not sure that this is clear. Is it understood that there is a transition between intrusive and extrusive? In other words, some volcanic rocks can be considered to be intrusive. Sometimes we call the in-between rocks 'sub-volcanic'. Does this help?
In the example the lava spreads out on an exposed surface, which is similar, but it doesn't originate as an "extrusive."
If there is one thing that people should know about geology is that things are usually more complex than one would like. Yes, volcanic rocks must have some intrusive source. It may be miles away, but it surely exists.
And "extrusive" is a term that makes no sense to me in this connection. A lava can spread on the surface if it originates from an above-ground volcano, which is apparently what is being called extrusive, but if it originates deep underground, as it does beneath the Grand Canyon, then it is an intrusive as it pushes up through all the rock strata already present. Seems to me that basalt can be either depending on where it originates.
Yes. But when we think of the Siberian Traps, or the Columbia River Basalts, or the Deccan Traps ("traps" is great word, eh?) we think of the extrusive rocks. Their ventssource is implied.
But back to the Cardenas. My expecting volcanism to have occurred after the strata was all laid down isn't some presupposition of mine, as you seem to be saying back upthread a ways, it is something I concluded, or let's say hypothesized, from looking at cross sections, especially of course the Grand Canyon cross section, where a magma dike is shown rising from basement rock through the Claron/Tertiary. The fault lines, the rising of the land, and the massive erosion all seem to have occurred in the same time frame.
The fairly obvisou conclusion is that there are multiple volcanic events...
Some of the magma beneath the canyon itself did not rise up through the strata but remained confined there -- diagrams show truncated intrusions. I connect it with the granite and the schist though you have some other explanation for that I haven't quite digested, and naturally also with that layer of Cardenas basalt -- but that basalt is also exposed to quite a depth on the surface of the canyon so it wasn't just confined though it seems to have originated beneath the canyon --yes, no?
Well, all intrusive rocks and extrusive rocks had a source somewhere beneath.
Maybe I'm not picturing this quite right but if that magma/basalt formed both the layer in the Unkar group AND the basalt that's spilled over in the canyon itself, how do you picture it as surface in the Unkar group which then got layered over?
As I said, they are different events, though you deny it. Detailed chemistry and age dates will confirm this.
Maybe I'm not asking this right. Since it's all over the place there, beneath the canyon and on the surface of the canyon, to me it makes sense that it would be a sill among those layers of the Unkar group. And I know you think I shouldn't be arguing with a geologist about such things.
No one knows everything. You can question all you want. You can argue all you want. It'a free world, at least here.
Edited by edge, : No reason given.

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edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


(1)
Message 266 of 740 (734312)
07-28-2014 1:46 AM
Reply to: Message 259 by Faith
07-27-2014 11:26 PM


Re: New depositions strangely different from old strata
Well, there's no point in arguing this out for the zillionth time but in a sense BOTH sides are making things up because that's pretty much all you can do with the prehistoric past.
Except that some of us can provide evidence.
And when you are dealing with made-up stuff, just hypotheticals, it's really quite possible to construct a whole web of evidence for them that looks pretty convincing but is still only a web of interconnected ideas, assumptions, plausibilities and so on. It's easy to confirm something you can't really test.
We test things all the time. I"m not sure what you are talking about here.
abe: the explanation for how the angular unconformity of Siccar Point formed is a case in point: it's all an argument from Reason, or plausibilities, abe: yes, of course based on observations of the rock itself, but still all you can do is INTERPRET what you're seeing, for the most part these things aren't testable.
Well then, show us the countervailing evidence, or prove the logic to be incorrect. Simply making assertions is schoolyard stuff.
There's no way to PROVE it formed the way Hutton said it did,
"Proof" is for mathematics and alcohol. Which one are you talking about?
... you either find the arguments persuasive or you don't, and for all you know there are all sorts of facts that are no longer in evidence that would change your view of it, or just facts you overlook.
Then you have your work cut out for you. The current evidence suggests an old earth. If you have other evidence, it's time to bring it on.
ABE: Looking for that picture of the South American formation, found "tepui" and Mt. Roraima which may be what I'm remembering but the picture that was posted here didn't show up. This one is maybe the closest:
Yes, I've been there. It's not really a mystery. it is an uplifted plateau that is being eroded away and leaving behind individual monuments or tepui.
Such enormous slabs of rock that originally had to have been strata suggest the Flood to my mind, and certainly not slow deposition over millions of years. But there's a case in point where it's a matter of finding an argument plausible or not. And besides such gigantic flat slabs of rock there are all kinds of strange/ weird/ bizarre geological formations all over the world that I can't see ever getting reproduced on the Old Earth model, that all suggest the Flood to me.
The weird thing is that these rocks are Precambrian. In other words, an entire sequence of rocks that you refuse to seriously discuss in the Grand Canyon.
And actually, the fact that they are so old is an argument that that, indeed, similar formations may not be forming now.

This message is a reply to:
 Message 259 by Faith, posted 07-27-2014 11:26 PM Faith has replied

Replies to this message:
 Message 272 by Faith, posted 07-28-2014 2:25 AM edge has replied

  
edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 267 of 740 (734313)
07-28-2014 1:49 AM
Reply to: Message 262 by Faith
07-28-2014 1:11 AM


Re: Cardenas
As for the dikes and sills, that just adds to the impression that the Cardenas could be a sill, just a particularly thick one.
Why is that? You have been given abundant evidence that the Cardenas is extrusive. Why do you simply deny?
Why do you assume that there is only one intrusive/extrusive event?

This message is a reply to:
 Message 262 by Faith, posted 07-28-2014 1:11 AM Faith has replied

Replies to this message:
 Message 270 by Faith, posted 07-28-2014 2:11 AM edge has replied

  
edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


(1)
Message 269 of 740 (734315)
07-28-2014 2:00 AM
Reply to: Message 268 by Pressie
07-28-2014 1:52 AM


Of course it is. You do know that tens of thousands of geologists all over the world get paid for doing geology full-time? In my country around 3 000; where exploration and mining companies are the biggest employers, followed by research organisations (exploration and mining companies provide most of the funds for research on geology), Universities (exploration and mining companies provide most of the funds for research on geology) , Government research organisations (exploration and mining companies provide most of the funds for research on geology), etc.? Every single person working full-time on geology knows more than you about the subject.
Good points, and you know what?
They test geological theories every day.

This message is a reply to:
 Message 268 by Pressie, posted 07-28-2014 1:52 AM Pressie has replied

Replies to this message:
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edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


(1)
Message 275 of 740 (734321)
07-28-2014 2:47 AM
Reply to: Message 272 by Faith
07-28-2014 2:25 AM


Re: New depositions strangely different from old strata
Yes, eroded out of an incredibly thick and extensive metamorphized sandstone LAYER, that covered some enormous amount of geography. Yes, I know that. Suggests the Flood to me.
Why? Where did that sand come from? You have the same problem here as you did in Monument Valley. There is no plausible source for the sediments in a global flood, particularly for sandstone.
Well in the Grand Canyon they are all jumbled up and need a lot of sorting out. I'll discuss them more when I've figured them out better. Meanwhile the tepui are clearly uncomplicated by comparison, though metamorphosed as one would expect of Precambrian rock.
So, while the Roraima Plateau is relatively undeformed the same age rocks in the GC are are disrupted. Why is that?
It's their hugeness, like the Coconino, the Redwall, the Dover Cliffs and other similar formations, their depth and breadth, that suggests they'll never be repeated on this planet, ...
But the processes that created sandstone were ostensibly the same. Do you have an alternative?
... not their age, which of course is only about 4300 years on my reckoning anyway.
Based on what? What is your evidence?
If I don't need to provide evidence, I could just as easily say that the entire planet was created last Thursday and my assertion is just as good as yours.
Edited by Admin, : Fix quote.

This message is a reply to:
 Message 272 by Faith, posted 07-28-2014 2:25 AM Faith has replied

Replies to this message:
 Message 284 by Faith, posted 07-28-2014 4:02 AM edge has replied

  
edge
Member (Idle past 1706 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 276 of 740 (734322)
07-28-2014 2:59 AM
Reply to: Message 274 by Faith
07-28-2014 2:32 AM


Far as I've seen, in the field the work you do doesn't even involve the enormous ages you've all said are necessary.
But 'enormous ages' explain what we see. In other words, what we see supports the idea of old ages. And we can use that information to look for more oil or certain fossils, etc.
I've also recently been looking at hundreds of cross sections, many of which were made for use in the petroleum industry, and often the time periods are just barely sketched in. Time really doesn't seem to be the big deal it's made out to be when it comes to practical geological work.
I differ. As an example, it might be necessary to know the age of a sill to know the thermal history of a basin and evaluate the petroleum potential. This is an actual example, by the way.
The really big deal is where the rocks lie, where they lie in relation to each other, their depth and so on, all the PHYSICAL stuff. Sure I can see that you need to know the order of the rocks and their RELATIVE age, but beyond that it doesn't seem to make any difference to your work at all.
Untrue. In some areas, we know that molybdenum deposits occur in intrusive rocks of a certain age. So, if I have two prospects, but one is older, which one should I put my money on? Remember, these are intrusive rocks and all I can say is that they are younger than the surrounding sedimentary rocks.

This message is a reply to:
 Message 274 by Faith, posted 07-28-2014 2:32 AM Faith has replied

Replies to this message:
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