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Author Topic:   The great breadths of time.
JonF
Member (Idle past 168 days)
Posts: 6174
Joined: 06-23-2003


Message 6 of 62 (313836)
05-20-2006 8:41 AM
Reply to: Message 1 by gigahound
05-18-2006 7:40 PM


Is it really so unrealistic that hot rock could cool within years/centuries?
Yes. Heat transfer is simple and well-understood. Under appropriate conditions "in the wild", hot rock cools in a few hours (e.g. underwater volcanic eruptions) or in a few hundred thousand years (e.g. large plutons, which are underground intrusions of magma that never make it to the surface) and everything in between.
if laboratories can simulate the formation of layers in a human lifetime, then what evidence is there that millions of years are a requirement for the formation of the Earth's layers?
I am not aware of any laboratory simulations or field observations of lithified (= turned into rock) layers in a human lifetime or longer. But the answer is that that there is lots and lots of other evidence, such as the many metamorphic rocks we see (sedimentary or igneous rocks that have been caried underground by subduction; spent millions of years down there turning into other kinds of rock in ways that take great time, temperature, and pressure; and finally returned to near the surface by uplift). Another good example is paleosols, layers of fossil soil; soil takes a long time to form, and there are lots of paleosols. And hardgrounds ... we don't want to ignore hardgrounds. And reefs, and ... and on and on and on. There's some good stuff on paleosols and plutons at Radiometric Dating, Paleosols and the Geologic Column: Three strikes against Young Earth Creationism. Hardgrounds at Hardgrounds and the Flood. See also Reefs and Young-Earth Creationism, Fossil Reefs, Flood Geology, and Recent Creation, A Paleosol Bibliography
I suppose the greater question here would be, are the great breadths of time considered Fact in science, or is it simply the Model that best defines our universe, such that scientists are actually open to other ideas, so long as the evidence makes sense and the "anti scientists" are simply making assertions under a misunderstanding?
It's sort of simultaneously fact and the best model. In science, there is always the possibility that other ideas will replace current ideas. This is true for any and all scientific conclusions. However, some conclusions are so well established that it's foolish to expect them to change, and we might as well call them facts. One example of such a conclusion is "if I jump out of my third-floor window and there's nothing there to stop me falling to the ground, I'm going to fall to the ground". Other examples of such conclusions are "The Earth is about 4.55 billion years old, life on Earth is about 3.5 billion years old, all life on Earth is descended from one or a few common ancestors, and evolution is the process by which the panoply of life arose".
So far, nobody has offered any evidence that makes sense and contradicts an ancient Earth. About the closest anyone has come is the RATE group's helium diffusion results (see, e.g., Helium Diffusion Age of 6,000 Years Supports Accelerated Nuclear Decay ). But there are still some severe problems with their model. They have a long way to go to establish helium diffusion as a valid determination of age, and to establish that the few samples they studied are typical and that we understand their history (the times they spent at various temperatures in particular environments) well enought to apply the method. They have to come up with a better explanation than "God did it", because that's just magic and "it's magic" is not acceptable as a scientific explanation, even if it's true. (If magic does really exist, science is forever doomed to ignore it). There are other, more techncial problems; see Young-Earth Creationist Helium Diffusion "Dates": Fallacies Based on Bad Assumptions and Questionable Data but be warned it's quite technical.
For the most part, the "anti-scientists" are simply making assertions under a misunderstanding. Alas, there's evil in the world, and some of them understand and are lying, and some are outright frauds.
You didn't mention radiometric dating, which is probably the premier evidence for the age of the Earth, consisting of hundreds of thousands of observations that are consistent with each other and other measurements. You might want to read Radiometeric Dating Does Work!. If you are interested in the basics of how it works, Radiometric Dating: A Christian Perspective is the classic on-line resource. The Agfe of the Earht, G. Brent Dalrymple, Stanford University Press, 1991 is a pretty technical expostion. There's gobs and gobs of other information I could provide if desired.
I bet the real geologists around here will also have something to say; I'm not all that conversant with feild geoilogy.

This message is a reply to:
 Message 1 by gigahound, posted 05-18-2006 7:40 PM gigahound has replied

Replies to this message:
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JonF
Member (Idle past 168 days)
Posts: 6174
Joined: 06-23-2003


Message 18 of 62 (314108)
05-21-2006 9:54 AM
Reply to: Message 12 by gigahound
05-20-2006 8:36 PM


These are the posts that I saw mention geological testing in labs. Now that I've re-read them, it seems I was mistaken, the labs seem to be studying the folding of the Earth, rather than the layering, however, there are folds within the layers, correct? So how far off base am I here?
I'm not sure what your point is here. There are often, but not always, folds within layers. That is sometimes taken (by Young Earth Creationists, AKA YECs) as evidence that they folded before they turned into stone. That's incorrect,; we know both theoretically and experimentally that solid rock can and does fold and "flow" under high pressures and temperatures as found inside the Earth. Rock Deformation Laboratory, High Temperature Deformation and Plasticity.
If Ned will allow me, in addition to the Supernova 1987A thread to which someone referred you, see also Hipparcos Satellite Data and How can we measure distances to more stars?.

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JonF
Member (Idle past 168 days)
Posts: 6174
Joined: 06-23-2003


Message 28 of 62 (314218)
05-21-2006 8:26 PM
Reply to: Message 26 by gigahound
05-21-2006 7:23 PM


Re: A bit of math
The math below makes sense, however, isn't this the same thought process that creationists use when describing the weakening of the magnetic field or the distancing of the moon? Your example shows that if a small rock cools at a specific rate, then a larger rock should follow the same rules with exponential results.
The difference is that Fick's law of cooling has been verified both theoretically (from extremely fundamental principles) and experimentally over incredibly wide ranges. Obviously we haven't done experiments on cooling of bodies of many-kilometer size, but if they cool differently than smaller bodies then all that we think we know about physics is really, really wrong, and a lot of our other predictions wouldn't work s well as they do. We have done measurements of chemical composition in such large bodies, and they follow Fick's law as expected (diffusion of atoms is the same thing as heat transfer, deep down). And, as I said in my first post in this thread, heat transfer is not a complex process.
The typical creationist extrapolation involves a very complex process, data taken over a very short time relative even to the creationist's 6000-year-old world, and extrapolating an overly-simplistic and purely empirical (no theoretical foundation) model over many orders of magnitude.
I've never seen a creationist seriously propose that Fick's law doesn't apply to large plutons. They have proposed that plutons were cooled quickly by flood waters and "expulsion" of water from inside the pluton, and they've produced some pretty incoherent 'explanations" of why grain sizes in plutons are so large (ignoring the fact that a pluton cooled rapidly by floodwater would have to be very fine-grained at the surface with larger grains inside, which we don't see); but even they don't deny Fick's law.

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JonF
Member (Idle past 168 days)
Posts: 6174
Joined: 06-23-2003


Message 34 of 62 (314476)
05-22-2006 9:42 PM
Reply to: Message 31 by gigahound
05-22-2006 8:31 PM


Re: Sorta moving on...
they should cool more slowly in the earth because they are insulated, somewhat like a thermos.
Yup. "Insulation" is a reasonable term, but it's not the perfect term. They cool more slowly in the Earth because the temperature gradient is smaller; the rocks around them are hotter than the atmosphere or surface. A thermos works because it's a lousy conductor of heat; for a thermos, "K" in Ficks law is a small number.
Does Fink's law apply over the entirety of this formation? Or is there other math involved?
Fick's law. A slightly more complex version applies; in the version presented before "K" is a constant. That's only strictly true as long as we are considering only one material in one state. If significantly different materials are involved, there's a different value of "K" for each, and if some of the stuff is molten and some is solid and some is gas there's a different value of "K" for each. But for approximate calculations the original versionis acceptable.
In the diagram, is shows the lava solidifying above and below a hot melt...is this accurate? I would think that the lava chute beneath the volcano would still be melted as well...
I bet it's accurate. I'm not a field geologist, but I'm guessing that the "pipes" through which the lava erupted are fairly small diameter compared to the extent of the "lake". That would lead to a high temperature gradient (large difference in temperature between the center of the pipe and the walls, and a small distance from the center of the pipe to the walls; divide the former by the latter and you get a much bigger number than for the lake with its large distance). That would lead to high heat transfer, cooling the magma in the pipe until it solidifies. Until the pressure of the magma below breaks it and we get another eruption.
might the volcano still be getting some energy from furthur below?
It is; it's hotter below than it is above, heat flows from hot to cold, therefore heat is flowing. But it's almost certainly negligible, becasue the distance is quite large, leading to a smallish temperature gradient.
Also, can Fink's Law be applied here?
Fick's law. Yes, or perhaps the more complex version, depending on where you draw the boundaries of the system you are considering.

This message is a reply to:
 Message 31 by gigahound, posted 05-22-2006 8:31 PM gigahound has replied

Replies to this message:
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JonF
Member (Idle past 168 days)
Posts: 6174
Joined: 06-23-2003


Message 37 of 62 (314733)
05-23-2006 8:02 PM
Reply to: Message 36 by gigahound
05-23-2006 7:18 PM


Re: Chemistry
The "universal" idea about rocks and minerals is that it takes Time, Heat, and Pressure for them to form. Time being the order of events required to pile on the pressure which creates the heat.
Different types of rocks require different amounts of time to form. Igneous rocks like basalt form pretty quickly.
The pressure and heat are found inside the Earth, but neither is caused by the other. The pressure is created by the weight of the rock above; the heat is created by radioactivity and some leftovers from the formation of the Earth. Rocks are "subducted" into the ground by the processes of plate tectonics, and there they encounter the heaat and pressure that turns them into metamorphic rocls. Then more plate tectonics processes return them to the surface or near the surface.
The 3 Types of Rocks
Discover How Rocks Are Formed!
Geology : Plate Tectonics

This message is a reply to:
 Message 36 by gigahound, posted 05-23-2006 7:18 PM gigahound has replied

Replies to this message:
 Message 38 by gigahound, posted 05-23-2006 8:27 PM JonF has replied

  
JonF
Member (Idle past 168 days)
Posts: 6174
Joined: 06-23-2003


Message 40 of 62 (314755)
05-23-2006 8:58 PM
Reply to: Message 38 by gigahound
05-23-2006 8:27 PM


Re: Chemistry
Well, there's really only one heating process; sometimes it's enough to melt the rock and sometimes it's not. When underground rock melts, the result is magma which can later turn into plutons, lava eruptions, or intrusions (which might be thought of as small plutons). When underground rock is heated and compressed significantly but not enough to melt it the result is metamorphic rock.
Plutons, which in general are mountains (at least, that's what I got from the reading I did.), are formed directly from molten mass.
They could be thought of as mountains, but they form and solidify completely underground, and are seldom called mountains. They sometimes become exposed by erosion of the surrounding material.
Mineral layers are actually formed from the heat produced by decaying atoms.
A "mineral" is a grain made up of one particular chemical composition and crystal structure. All rocks are made up of at least one mineral and are usually made up of many minerals. I think you mean "rock layers".
Magma (which is molten rock underground) is indeed melted by the heat due to radioactive decay of unstable atoms, although some of the heat is left over from the formation of the Earth. Metamorphic rock (underground rock which is heated and compressed enough to be changed significantly but is not heated enough to melt) is produced by the same heat plus the pressure of the rock above.
Fick's law is great for tracking the cooling of molten masses, but I assume it cant be used on layered minerals (except under controled conditions?) because they would be physically cool (radioactive decay wouldn't happen fast enough to actually heat the mass would it?).
Fick's law can be used for any situation in which something is diffusing between an area of high concentration and an area of low concentration. This includes heat transfer under any conditions. The math can get pretty complex when the shape of the thing you are interested in is complex and/or its composition varies significantly from place to place and/or what's going on at the boundary is complicated. But computers can do complex calculations very well.
Most of the heating of rocks is not from radioactive decay inside them; it's from heat transferred from the surrounding rocks, much of which heat originates ultimately in the deeper interior of the Earth. Earlier in the thread we saw that it takes a kilometer-sized pluton millions of years to cool ... well, it takes a long time for the originally-molten Earth to cool, plus heat is still being generated inside.
Geez, where are all the real geologists in this thread? This isn't my strongest suit, and this not a great medium for teaching basic geology ('cause doing diagrams is a PITA).
I suggest you look at my most-recently-posted links.

This message is a reply to:
 Message 38 by gigahound, posted 05-23-2006 8:27 PM gigahound has replied

Replies to this message:
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JonF
Member (Idle past 168 days)
Posts: 6174
Joined: 06-23-2003


Message 41 of 62 (314756)
05-23-2006 9:00 PM
Reply to: Message 39 by MangyTiger
05-23-2006 8:35 PM


Re: Sorta moving on...
In general terms I think that is just Newton's law of cooling
Pretty general ... but Fick's law is more general, and Netwon's law of cooling is a special case of Ficks' law.

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JonF
Member (Idle past 168 days)
Posts: 6174
Joined: 06-23-2003


Message 56 of 62 (315098)
05-25-2006 9:50 AM
Reply to: Message 45 by gigahound
05-24-2006 6:04 PM


Re: The story so far.
For instance, it appears to me that while Fick's law shows the cooling process to be slow, isn't the process also hampered by the additional heat generated by continuing pressure, ongoing radioactive decay, and the rising of heat from the depths below?
"Hampered" is not really the right word. Fick's law still applies and works just as well as long as you properly account for what's happening in and around the region of interest. The process of cooling is the process of cooling and is described by Fick's law but to get the right answer you have to dump in all the data. Sometimes we leave out some of the complicating data and calculate a simpler problem and get a "wrong" answer, but we can often predict how the answer is wrong; that is, we often can tell whether the time we calculated is too short or too long. So a simpler calculation can still be useful
For example, radioactive decay and heat rising from the depths below add heat to the system. Radioactive decay inside the system adds heat directly; radioactive decay from outside the system and heat rising from the depths below add heat to the system by conduction across the boundary of the system. That extra heat slows down cooling. That is, if you calculate the cooling of a pluton without accounting for radioactivity and heat rising from the depths below, the answer you get will be shorter than the time it will actually take a real pluton to cool. So radioactivity and heat rising from the depths don't help the creationists at all; it just makes things worse for them. (The calculations we do usually do include the external heat but do not include the heat generated by radioactivity inside the pluton).
Pressure doesn't have much (if any) effect on cooling ... it is possible for pressure to force the material to change state to a different form that conducts heat differently, but that's rare.
The only YEC "discussions" I've seen on how plutons cool involve water, which is an excellent conductor of heat and can absorb quite a bit of heat. Unfortunately for the YECs, water on the outside of the pluton isn't enough, because you would still have to transfer all that heat from the middle of the pluton to the edge, and that takes time. Lots of time. So you need an extensive network of magically formed cracks (don't forget the pluton starts out as liwuid and is under tremendous compressive pressure ... what opens up cracks?), a source of relatively cool water (the magical flood? But we need this water underground ...) and, after the pluton cools, some more magic to close up the cracks and weld the material together, 'cause we don't see those cracks today.
Yet another problem with YEC scenarios is the grain size in the plutons. Grains are little chunks of individual minerals in rocks. Crudely put, fast cooling means small grain size, slow cooling means big grain size, and very slow cooling means very big grain size. Plutons have very big grain size. That means very slow cooling. There have been a few experiments that show that fast cooling can occasionally produce large grains under special circumstances, and maybe those circumstances actaully apply "in the wild" once in a while, but they don't always apply in the wild; at least some (if not all) plutons with very large grain sizes cooled very slowly.

This message is a reply to:
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JonF
Member (Idle past 168 days)
Posts: 6174
Joined: 06-23-2003


Message 57 of 62 (315100)
05-25-2006 9:54 AM
Reply to: Message 55 by gigahound
05-24-2006 7:58 PM


Re: Chemical process
By chemical process, are we describing creation of the layers/rocks or the creation of heat
Chemical processes are involved in creating solid sedimentary rock from un-consoldiated material, and in creating the particular minerals that form in igneous rock. Although the chemical processes always absorb or release heat (depending on the particula process), in practice the amount of heat is small compared to other sources and can safely be ignored.

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JonF
Member (Idle past 168 days)
Posts: 6174
Joined: 06-23-2003


Message 58 of 62 (315104)
05-25-2006 10:18 AM
Reply to: Message 51 by gigahound
05-24-2006 6:35 PM


Re: Heat sources
Is there a difference between the two statements or is it just the wording?
It's pretty much just the wording. "Insulation", to most people, means something that is a really horrible conductor of heat. Rocks aren't great conductors of heat, but they're not really horrible at it.
If you look back to Fick's law on the first page, there are two things involved; how well the material conducts heat ("K") and the "thermal gradient" (d2T/dx2). If K is very small, heat flows slowly. That's insulation.
If d2T/dx2 is small, heat also flows slowly. That's not necessaarily insulation, depending on what K is.
In the case of the entire Earth, K is sort of middlin'-size and d2T/dx2 is very small because of the long distance (dx) from the center of the Earth to the surface. In the case of the upper layers of the Earth, K is still sort of middlin'-size and d2T/dx2 is still small, but now it's because the distance (dx) is middlin' and the difference in temperature (dT) is relatively small.

This message is a reply to:
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JonF
Member (Idle past 168 days)
Posts: 6174
Joined: 06-23-2003


Message 60 of 62 (315198)
05-25-2006 9:26 PM
Reply to: Message 59 by gigahound
05-25-2006 5:20 PM


How likely is it that some rock has cooled and reheated in cycles before being disconnected from it's heat source?
Cyclic cooling and heating largely doesn't happen. "Being disconnected from its heat source" is "physically rising out of the hot interior to nearer the cooler exterior". Then it cools. It doesn't get heated again until it gets sent down to the hotter interior again by subduction, millions of years later. Of course it might get eroded before the subduction happens.
Can we determine how long a rock has been hot before it began cooling?
Not really.
For igneous rocks, no; before they began cooling they weren't rocks, they were molten rock materials. The dating methods we have start the clock ticking when the rock solidifies.
For sedimentary rocks, your question is meaningless; cooling is not involved.
For metamorphic rocks, we can sometimes find a time that is longer than the time the rock was hot but not molten. Under some circumstances we can look at two radiometric clocks in metamorphic rocks, one of which tells us when the metamorphosis ended (the rock cooled) and the other of which tells us when the parent igneous rock formed (which is obviously before the rock was subducted and reheated).
Is there a "line" that determines when a rock is considered hot?.
Not a solid one. Depends on what you are looking for. Melting is almost certainly hot. Different minerals melt at very different temperatures. Rocks metamorphose at temperatures significantly under melting, and different minerals start metamorphising at very different temperatures.
Does it have to be hot throughout or is the outer region enough?
Enough for what?
Just the outer region is enough to burn your fingers if you try to pick it up.
Melting requires that all the minerals reach thier melting point, throughout the rock.
Re-setting the radiometric clock so the rock looks new to dating methods requires getting the entire rock to some significant percentage of its complete melting temperature.
Can we duplicate the heating process in a lab? For instance, can we seal a rock in a container and record an increase in temperature from the readioactive decay? Can we detect an increase in the temperature of the container?
Yes, and yes, and yes. The only thing we can't do in a lab is subject it to high temperature and pressure for a million years or therabouts. Look at the links I posted in Message 18. I think you need to spend more time reading the links and studying the material.

This message is a reply to:
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