How the geo strata are identified as time periods

It may be interesting to point out that non-clastic sedimentary rocks also exhibit characteristics that attest to their status as ancient.Limestone for examples requires trillions upon trillions of sea creatures to be born, live, die and slowly sink to the bottom of the ocean.Evaporite deposits require the deposition area to be continuously flooded (oops bad word) with "salty" water and then evaporate. This will leave behind a thin film of evaporite material. Some evaporite deposits are 10s if not 100s of meters thick.These are just some examples out of many of processes required to create these rocks that, unless the laws of nature fundamentally change, cannot happen except over very long spans of time. I mentioned the cooling of an intrusion as one. The actual process of metamorphism is another. These things simply cannot happen fast. If they did, the outcome would not be the same. I'll repeat my previous analogy. You can try to bake a cake by applying the same amount of heat it would normally get over its entire bake time in a nano-second; but the outcome will most certainly not be cake.I'll also point out that although these testaments to the earth being ancient, they don't help as much as other dating techniques when trying to assign actual ages. For a given layer, you can get an idea based on this knowledge to get a rough estimate of how long it might have taken all that sand to pile up, but there is much more potential for error in those kinds of estimates.

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Of course, biblical creationists are committed to belief in God's written Word, the Bible, which forbids bearing false witness; --AIG (lest they forget)

Probably not. Iron meteorites tend to have very small amounts of long-lived radioisotopes, and many of them cannot be dated. Apparently the Canyon Diablo meteorite is not a very extreme case. But it is the most extreme case we've found. Seems fair to me

I like paleosols. Loads of 'em in the Grand Staircase. Root traces. Soil horizons. Characteristic microstructures. Mmmmm-mmmm good.

Couple minor points first.
Jazz-message 45--was 'phenocryst' the word you were looking for?Don`t think it has been spelt out that the source rock in metamorphism can be igneous, sedimentary or even other metamorphic rocks.I think YECs have a vision that sedimentary layers are like the skins of an onion, homogeneous all the way around the sphere. Whereas, sed. land deposits depend on relatively local environmental conditions (which can vary over the life of the layer) and source materials, so that you wouldn`t get identical silt depositions world-wide, contrary to the fluvial fallacy (sorry, Ned )

You think wrong. See my Message 19:

Did I mention your name?

Thanks for the terminology that I had forgotten. I knew there was a name but the only thing that kept popping up in my head was Xenolith but I knew that was not right because "xeno" means foreign and these crystals were not foreign. We have to be careful, YEC's vision is not on topic for this thread. Even if it was, I think your characterization is only true in very rare and highly ignorant cases.

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Of course, biblical creationists are committed to belief in God's written Word, the Bible, which forbids bearing false witness; --AIG (lest they forget)

I disagree, but let`s save it for a thread explaining masses of minerals in sed. layers.

The fact remains that the evo interpretation is evidentially falsified for the viewing pleasure of even the most common of men.
Since, the sedimentary layers are defined by the constituents they possess. And, the constituents of a particular sedimentary layer is relatively homogeneous.
(That's why the tell-tale color/shading bands exist)The idea that for millions of years only one particular set of sedimentary constituents was deposited per any particular layer in question is unbelievable.Joman.

This thread is being used for explaining how geologists associate layers with time periods, so questions about this process is what's appropriate here. If you'd instead like to challenge the views of modern geology on the formational processes of geologic layers then you should probably find a more appropriate thread, or perhaps propose a new one.--Percy

This thread is not about sedimentation although I will note that your characterization of what mainstream geologic theory says about sedimentation is vastly flawed and overgeneralized. You should remedy your ignorance of geologic theory and principles in an appropriate thread about sedimentation.This thread is about identifying how mainstream geology identifies the various geologic strata as time periods. It is not about the validity or consequence of that identification. I hope that no one else is baited by your off topic post to reply accordingly.

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Of course, biblical creationists are committed to belief in God's written Word, the Bible, which forbids bearing false witness; --AIG (lest they forget)

In terms of dating geologic age, basalt is an excellent marker. Using Potasium 40 or Argon dating will get you a fairly accurate date of a volcanic event.Now for arguements sake we have a layer or basalt, the sedementry rock, then more basalt - We can be fairly certain of the time period of the sedimentry rock.For the sake of the discussion, lets assume that the layer of sediment has a fossil percular to it. By looking for this particular fossil in other sedimentry rock will give us the date of that rock as well.Edited by MG1962, : No reason given.

The point I made is that it is unreasonable to think that sediments of one particlar make up of constituents were laid down over any great length of time. This conclusion means that the uniformitarian timelines are unreasonable with respect to sedimentary strata.
The responses so far were not scientific ones.
I think I know what the problem with reponding to my point is. The evo's on this thread have searched the web for an easy answer and have found the search to be useless.
Which is why I chose this simple proof.Joman.

Hi Joman,Perhaps the explanations of why you're off-topic in this thread weren't sufficiently clear, but we'd like to keep this thread on-topic and not turn it into a discussion of what the topic actually is, so let me try another approach.If you inquire over at the General discussion of moderation procedures - Part 7 thread I'd be glad to explain at any length necessary why you are off-topic in this thread, but continuing to post off-topic here will likely result in suspensions.

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--	Percy
	EvC Forum Director

Some volcanic horizons are indeed very useful for radiometricly dating, and for the dating of sediments between volcanic horizons. But basalt, the mafic (high iron and magnesium) end member of the types of igneous rocks is (and someone correct me if I'm wrong) not radiomentrically datable by the common methods, including such as Potasium/Argon, Uranium/Lead, and variations there of. Basalt is very low in Potasium and Uranium.I don't know if there are more recently developed radiometric methods that are useful for dating basalts.Now, if you had instead said rhyolite (the felsic end member, high in feldspars and silica) you would have been on solid ground. Rhyolite very much so can have useful Potasium and Uranium contents. OK, if you substitute something along the lines of rhyolite for basalt. OK, to a degree. If the fossil has been shown to have a short species life time, then it can be used to date a sedimentary rock to within a fairly narrow time span. But if the fossil has a long species life time, then the siedimentary rock can only be dated to be within that long time span.Moose

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Professor, geology, Whatsamatta U
Evolution - Changes in the environment, caused by the interactions of the components of the environment. "Do not meddle in the affairs of cats, for they are subtle and will piss on your computer." - Bruce Graham

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"The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness." - John Kenneth Galbraith

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"I know a little about a lot of things, and a lot about a few things, but I'm highly ignorant about everything." - Moose