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Stupid Question: Rock Age?


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#1 JayShel

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Posted 17 January 2012 - 09:12 PM

If all the matter on earth existed since the earth was formed, then how can rocks have different ages? Aren't they all as old as the earth? What starts, or resets their time clock so that we can differentiate between different rock "ages". What does the age of a rock really mean?

I apoligize if this is geology 101, but I really can't think of a reason right now...radiation deposited from outer space? Theres probably a really simple explanation...

#2 MarkForbes

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Posted 17 January 2012 - 09:36 PM

I also have wondered about this in the past. It depends also what rocks you are talking about. Sedimentary rocks are different from others also in terms of dating them. When they are talking about the age of rock they don't mean the age of the matter, but when that specific mineral is supposed to have formed.

#3 ikester7579

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Posted 17 January 2012 - 10:01 PM

If all the matter on earth existed since the earth was formed, then how can rocks have different ages? Aren't they all as old as the earth? What starts, or resets their time clock so that we can differentiate between different rock "ages". What does the age of a rock really mean?

I apoligize if this is geology 101, but I really can't think of a reason right now...radiation deposited from outer space? Theres probably a really simple explanation...


I'm glad that someone figured this out, I was begining to think I was the only one. You see if all matter came from the big bang it is supposed to date back to that proving where it came from. But because it does not means all age dating is flawed. So you figuring out that things from the earth don;t date the same is along those same lines.

#4 Geode

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Posted 17 January 2012 - 11:31 PM

I also have wondered about this in the past. It depends also what rocks you are talking about. Sedimentary rocks are different from others also in terms of dating them. When they are talking about the age of rock they don't mean the age of the matter, but when that specific mineral is supposed to have formed.

Sedimentary rocks are dated to the time of their formation as an aggregate of mineral matter. Some sedimentary rocks rocks are formed from one mineral, but many are not. Some sedimentary rocks form chemically by precipatation and the date of the mineral formation would be about the same as the rock. However sedimentary rocks can be comprised of multiple mineral components that formed at dates quite separated from each other.

#5 jason777

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Posted 17 January 2012 - 11:37 PM

One of the assumptions of potassium argon dating is that before a metamorphic rock solidifies, it looses all argon and all detectable argon afterwards is radiogenic. The one problem I've noticed is that the outer crust of magma solidifies first, which prevents argon gas from escaping. That's why the same sample can give widely discordant ages. So, yes; all of the earth's matter is the same age, but the date that a rock solidified from a molten state is believed to reset the atomic clock.

Enjoy.

#6 Geode

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Posted 17 January 2012 - 11:54 PM

If all the matter on earth existed since the earth was formed, then how can rocks have different ages? Aren't they all as old as the earth? What starts, or resets their time clock so that we can differentiate between different rock "ages". What does the age of a rock really mean?

I apoligize if this is geology 101, but I really can't think of a reason right now...radiation deposited from outer space? Theres probably a really simple explanation...

Rocks are basically a naturally occuring aggregate of minerals and date to the time that the component minerals came together as the solid that defines the rock (as named) so they can have vastly different ages.

A "reset" can occur when the rock is melted, dissolved, re-crystallized through metamorphism or mechanically disaggregated. The material then can come together again through solidification or deposition and the new rock(s) will date from when this occurs.

#7 JayShel

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Posted 18 January 2012 - 04:59 AM

Rocks are basically a naturally occuring aggregate of minerals and date to the time that the component minerals came together as the solid that defines the rock (as named) so they can have vastly different ages.

A "reset" can occur when the rock is melted, dissolved, re-crystallized through metamorphism or mechanically disaggregated. The material then can come together again through solidification or deposition and the new rock(s) will date from when this occurs.


Then my questions now are:
1) How did the radiation get in the rock in the first place?
2) Wouldn't a "reset" leave the byproduct of previous radiation in the rock so it would still date older?
3) Radioactive byproduct within the rock would be high if there was a lot of radoactive isotopes deposited and be less if there is less, right? Does the dating method have a way of factoring this in?

#8 Geode

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Posted 18 January 2012 - 05:15 AM

Then my questions now are: 1) How did the radiation get in the rock in the first place? And wouldn't a "reset" leave the byproduct of the radiation in the rock so it would still date older?

Some minerals contain elements that are naturally radioactive and the inclusion of these elements makes the rock have radioactivity. Including radioactive minerals that have been mechanically broken out and not "reset" in new sedimentary rocks would leave the individual mineral grains of the same age in terms of the half-life of radioactive elements (but measuring the situation could be problematical due to weathering). Melting the mineral grains and then later recrystallizing them as new mineral forms would create newly formed mineral material in terms of radioactivity and could be called a "reset" and no, it would not leave it the resulting minerals dating older in radiometric dating terms.

#9 MarkForbes

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Posted 18 January 2012 - 07:05 AM

Sedimentary rocks are dated to the time of their formation as an aggregate of mineral matter. Some sedimentary rocks rocks are formed from one mineral, but many are not. Some sedimentary rocks form chemically by precipatation and the date of the mineral formation would be about the same as the rock. However sedimentary rocks can be comprised of multiple mineral components that formed at dates quite separated from each other.

That's how I understood it as well. There would be at least three different "ages" involved:
- start of the rock material to exist.
- Formation of the mineral compound.
- Formation of the sediment.

Some materials in rocks are indeed radioactive and have half lives. The ratio of different materials is sometimes used to attribute an age to them. That has been discussed previously including the problems with that kind of dating methods. But I think the OP is aiming more at the semantic problem of "This rock is X years old" and "this one is Y years old".

#10 ikester7579

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Posted 18 January 2012 - 07:21 AM

Sedimentary rocks are dated to the time of their formation as an aggregate of mineral matter. Some sedimentary rocks rocks are formed from one mineral, but many are not. Some sedimentary rocks form chemically by precipatation and the date of the mineral formation would be about the same as the rock. However sedimentary rocks can be comprised of multiple mineral components that formed at dates quite separated from each other.


What you pretty much have done here is proved what I said, Age dating does not date the actual age of the matter but only dates the formation of the mineral. Hence when the dating markers are left. So like the old earth believers often point out to the YECs, that the Biblical time-line does not match the age that it dates, they have the same problem because all matter should date as old as the universe since it came into being at about the same time, So what this basically means is that even though the age of the earth dates 4.6 billion years old, the actual date of the matter that made it is around 15 billion years old. So this would show that those who believe in billions of years have a similar problem, Is the earth as old as it dates, or as old (4.6 billion) as the matter is from the big bang (around 15 billion)?

But as the YEC belief goes, God created with age already added because age is part of the formulation of how things work the way that they do, And since God created all living matter already aged and ready to reproduce after it's kind, then there is no problem adding in that God can do the same exact thing with dead matter. Why do it this way? A certain "aged" sun needs to be used so that it's a certain size and mainly stable so that it does not destroy life on this planet. The reason the star needs to be stable upon creation is because at it's current distance from the sun an unstable star would strip away the earth atmosphere with huge erruptions on the surface which can send enough solar wind our way that our magnetic field could not deflect it all. So our distance and the age of the sun is very important. then we have the age of the earth, The earth has to be created a certain age to be cooled down enough to support life.

Now why go to all the trouble to create with age when God can do anything? God is not a law breaker. To berak His own laws would not be setting a good example for us His creation has to abide by the laws (laws of physics) he sets for it. And our ability to understand it shows that it makes since and creates order unstead of chaos. Laws of physics origins are unexplanable in any natural since. For there is no natural way for them to come into existence and science has no idea how to take the first step in doing so. So the origins of the laws that exist are ignored by the scientists who's worldviews support naturalism. While all along knowing that even the laws that we make require intelligence to do so. And because the laws are balanced to work together to create order instead of chaos, one could also conclude that they are a carefully put together formula that with one law off would cause chaos. And through our own experience we also know that formulas require intelligence because they require thought.

So what allowed God to create with different ages without breaking the laws that existed as we see them today? The 6 days of creation were done before sin. And since the Bible makes it clear that sin caused death, and time without death is eternal means that the 6 days of creation were done under "eternal laws" instead of "non-eternal" as we currently observe. Which means that time passes but age is a constant (never changes). Compared to what we know which is the exact opposite. So how would a Creator create under laws where age is a constant which means whatever age something was created it would be that age for all eternity, or at least until sin? Knowing this means that God would have to create with age already added whle keeping in mind that sin will change things. So the creation before sin has to be created so that when the laws after sin changed it, it does not destroy what was created. In other words God has to create a universe that will work under 2 set of laws. The laws before sin, and the laws after sin. Understand? This is why the laws after sin cannot explain the creation under the laws before sin. To try and do so would be like trying to make a vanilla cake with the ingredients that it takes to make chocolate cake. The results are never going to be what you want or understand until you realize that soething needs to be different to make it work.

Science cannot prove that the laws remained the same throughout all time, so the possibility of this is very real. And it totally supports and explains the YEC view.

#11 jason

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Posted 18 January 2012 - 07:18 PM

arent miracles also breaking of those laws?

how does a dead thing live again when jesus raised dead men from time to time?

i think god does at will and leisure disrupt laws but do so when he sees fit and its rare that such things occur. i do think god can raise the dead but that is rare.im not one to believe at present healing promises as taught in charismatic circles.

#12 JayShel

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Posted 18 January 2012 - 08:21 PM

Melting the mineral grains and then later recrystallizing them as new mineral forms would create newly formed mineral material in terms of radioactivity and could be called a "reset"


What exactly does that mean? The minerals change structure, so new kinds of minerals are formed. Does this mean that radiometric byproducts such as lead and argon are turned into different elements, or fused into new molecules, or somehow escape the rock so they are no longer a factor in the dating process?

#13 Geode

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Posted 19 January 2012 - 08:32 PM

Posted Image


Melting the mineral grains and then later recrystallizing them as new mineral forms would create newly formed mineral material in terms of radioactivity and could be called a "reset"

What exactly does that mean? The minerals change structure, so new kinds of minerals are formed. Does this mean that radiometric byproducts such as lead and argon are turned into different elements, or fused into new molecules, or somehow escape the rock so they are no longer a factor in the dating process?

Yes, in the process of recrystallization new minerals form. Radiometric by-products from the minerals that once existed, such as lead, can be incorporated in the new minerals and this does involve molecular changes. Argon will have been allowed to "escape" from a magma, since it is in a molten state.

Whatever resulted from nuclear decay in minerals of the old rock will no longer be part of the basis of dating the recrystalized rock. The new rock has a later origin and has been "reset" in these terms.

#14 JayShel

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Posted 19 January 2012 - 09:04 PM

Yes, in the process of recrystallization new minerals form. Radiometric by-products from the minerals that once existed, such as lead, can be incorporated in the new minerals and this does involve molecular changes. Argon will have been allowed to "escape" from a magma, since it is in a molten state.

Whatever resulted from nuclear decay in minerals of the old rock will no longer be part of the basis of dating the recrystalized rock. The new rock has a later origin and has been "reset" in these terms.

How common is it for a rock to date younger or older than evolutionary presuppositions? And if a rock dates more or less than you expect, do you assume that it has been contaminated? How do you go about determining where the error lies?

#15 Geode

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Posted 19 January 2012 - 09:46 PM

How common is it for a rock to date younger or older than evolutionary presuppositions? And if a rock dates more or less than you expect, do you assume that it has been contaminated? How do you go about determining where the error lies?

"Evolutionary presuppositions" are not really part of the science of geology. In terms of the dating of rocks, they were first dated relative to each other using fossils before the theory of evolution came to be used in biology (after Darwin published). The process was not based upon evolution. Radiometric dating is not based upon "evolutionary presuppositions" either.

The radiometric dating of rocks is done with samples that are taken as carefully as possible. If a number of age dates from the same rocks are derived properly in terms of sample collection and laboratory procedures, most will fall within the same "error brackets" and if a few are "outlyers" they would be suspect in terms of contamination.

#16 JayShel

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Posted 20 January 2012 - 04:10 PM

"Evolutionary presuppositions" are not really part of the science of geology. In terms of the dating of rocks, they were first dated relative to each other using fossils before the theory of evolution came to be used in biology (after Darwin published). The process was not based upon evolution. Radiometric dating is not based upon "evolutionary presuppositions" either.

The radiometric dating of rocks is done with samples that are taken as carefully as possible. If a number of age dates from the same rocks are derived properly in terms of sample collection and laboratory procedures, most will fall within the same "error brackets" and if a few are "outlyers" they would be suspect in terms of contamination.


How would you be able to discern a large contamination event?

#17 Geode

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Posted 20 January 2012 - 07:51 PM

How would you be able to discern a large contamination event?


In general I wouldn't expect a widespread contamination event, but I would think that having many erratic age determinations would indicate problems with contamination.

#18 JayShel

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Posted 20 January 2012 - 08:29 PM

What are the ways that rock ages can be contaminated, and how often does contamination happen in your experience? (I have so many questions I know, sorry)

#19 Geode

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Posted 21 January 2012 - 05:15 AM

What are the ways that rock ages can be contaminated, and how often does contamination happen in your experience? (I have so many questions I know, sorry)


With radiometric dating methods percentages of parent and daughter elements must be compared, so adding or subtracting to the amounts of either from sources outside of the sample will result in erroneous dates due to "contamination"...

My experience is really i regards to geochemical analysis where contamination must be rigorously guarded against...however, in practice enough care is generally taken to prevent much contamination and valid results are usually obtained. I think it is much the same in radiometric dating, and using multiple methods limits the chances of contamination skewing results and adds support to the ages obtained by using independent means of determination.

#20 MarkForbes

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Posted 21 January 2012 - 06:56 AM

There would be more then one type of contamination be possible during the lifecycle of a piece of mineral.
Also consider that something can accumulate or be washed out.




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