How the geo strata are identified as time periods

I've been realizing I really want to know how geologists are so sure that a particular stratum found anywhere on earth belongs to a particular time period. What are the methods for determining this? Fossil content? Relation to other layers? Are there some areas where it is hard to determine?I'd like to sit back, ask questions and otherwise watch on this one.August 29 at 5 pm Eastern This thread is not answering my question but has become a General Geology thread. Edited by Faith, : No reason given.

Of course, this is obvious. Sounds reasonable, depends on what this means in practice. Not sure this is necessarily true. It seems to me that differing amounts of sediments could take quite different time periods to accumulate -- no reason the process has to be uniform. A deep layer might have been quite rapidly laid down and a thin layer could have taken much longer. I see no necessary formula here. I don't know what this means. This is very problematic, since what is often described as obvious signs are not at all obvious, among other questions about the idea.But I don't want my ideas to become the focus of this thread. I'd just like to hear some discussion of how layers are determined to belong in particular time periods of the Geologic Time Table.

What I'd really like to see on this thread is discussion of some very specific locations and formations and how they were assigned to particular time periods, actually rather than hypothetically. The question I had was really about how you determine at a given location whether and how the various layers represent the established time periods of the Geologic Time Table.That is, you come across these strata in a new location. How do you determine that one is Jurassic, another is Carboniferous etc etc.I mean, I'm aware that the sedimentary composition is not always the same from one location to the next. That pretty much leaves fossils as the indicator of the time period. But in some places it seems that while the order of the fossils may stay predictable things may change in the appearance of the layers or something like that.Also, using the fossils as an indicator would seem to beg the question in some cases, since you have defined in advance that a particular kind of fossil only occurs at such and such a depth. Edited by Faith, : No reason given.

OK, guys, I can see you want me to work hard for this information; might as well go get me a degree in geology. I could look up all the articles about geology on the internet myself, you know, and struggle through them all to see if they discuss how strata were named at particular locations, which would take years. I've actually spent a fair amount of time in that sort of pursuit in my sojourn at EvC. So. Well. I don't know. I guess we can let this thread take it's good ol' time and I'll answer when I get around to studying the stuff. Or not.

I'm not sure his post works for me. I was hoping to get some information about techniques of identifying strata, in a more or less casual format. Fossils or character of strata or whatnot. General principles, specific examples. I kind of thought this might not be all that hard for anyone with a minimal background in geology. I might be wrong there, but what I know about geology I learned online and I haven't run across much information about the methods of identifying the layers. General principles of geology as a whole, though, lots of that out there.Jar then started asking questions about the specifics of sedimentary formations. I do know a few things about that and have thought about it to some extent. I know I don't agree with jar about some of it from other threads, and by his laying out the format for this thread with those questions he could force me into my Flood explanations, which is one thing I really wanted to avoid on this thread. I don't want to argue the two paradigms on this thread; that's what happened on the mutation thread where I also didn't want to argue them. I just want to know how geologists, evolutionist geologists, arrive at their identification of strata if it's possible to say.I COULD get very interested in all this if I had the time, and the money for some neat but very expensive books about aspects of geology, but I don't have all that much of either. And forget hiking expeditions to various sites. I never was much of a hiker and now I'm too old and physically out of shape for that level of involvement. This is going to have to be a cerebral undertaking.Anyway, I'm not looking for an entire course in geology on this thread, but it appears that's what jar and Nosy, and to some extent anglagard and Jazz, are turning it into.Edited by Faith, : No reason given.Edited by Faith, : No reason given.Edited by Faith, : No reason given.

Hey, I'd enjoy watching jar teach you geology. It might not answer my questions but it would be interesting. If he's game, go for it.But I don't think even a basic course in geology would answer this particular question. I'm not sure, I just don't think so because it's not easy to find a discussion of this at online geology courses. Lots of general principles of geology are there, as I said, but little or no discussion of such particulars as how the strata all over the earth are identified.{Edit: The strata don't come in neat predictable little arrangements; they show up in all kinds of different sedimentary characters, so identifying which is what period has to take some ingenuity.Edited by Faith, : No reason given.Edited by Faith, : No reason given.

William Smith is interesting -- I'd probably like to read the book myself sometime. But I would expect there to be a continuous deposition in a relatively small area of the planet -- meaning by "small" the entire British Isles plus half the European continent possibly.Those observations are interesting of course, but my question has to do with the impression that the layers aren't continuous like that all over the planet. There are layers everywhere but their character changes. So I'm curious how geologists correlate the information from one set with others in such a way that a worldwide deposition of strata can be reliably identified as representing periods of time -- periods of time that can be tracked everywhere even if the characteristics of the strata are appreciably different.See, maybe naively, I just thought that people with some geology background would simply know the main principles of how this is done off the top of their heads, and have examples in mind to illustrate it.

I guess I have to disagree with your first proposition...

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unless there are signs that the area has been disturbed, a layer under another layer is likely older than the layer above?

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...after spending an hour and a half this morning reading up on experiments in sedimentation by Guy Berthault in which it was shown that it's possible for currents of water to carry a lot of sediment and precipitate it out all at once into separate layers. I'd read Henry Morris along these lines years ago but had the impression that the layers had accumulated sequentially. Berthault's experiments show otherwise. I hoped to find some pictures of the experiments online but haven't yet. Apparently there are some videos available though.CSAMA - 404 Error I didn't want to get into this kind of discussion though. I didn't want to bring up the flood or alternative explanations of sedimentation or anything like that. All I wanted to know, and still want to know, is how geologists NAME the strata according to the Geo Time Table when there appear to be quite a few differences in the layering across the planet. Is it really possible to identify a continuous layer across the entire planet and how do they do this? If it IS possible, this won't be disputed by flood theory.Edited by Faith, : No reason given.

I SAID, Percy, that I do NOT want to approach this as a debate. I don't want to discuss the Flood. How much clearer can I possibly be about that? But jar asked questions and I answered them. Better he hadn't asked the questions.Jar's supposed step-by-step approach to this is NOT a step by step approach to what I asked for. It's not even a step approach to anything. He merely asked a series of questions and I answered them. This is NOT the way to approach this subject. I answered his questions in a way that shows I don't accept his way of construing them. How does that get us into any kind of step to anything whatever?In my OP I said I'd like to ask questions and otherwise watch. Well, so far, NOBODY has honored that request. Jar asked ME questions, questions I see no relevance for; others gave information that didn't answer my questions but required me to do further research. That's OK, I may yet do it, but it's not what I asked for.I have no idea why anybody thinks jar has found the right way to approach this subject. I don't see it. There are no steps in that list of questions.I've asked the questions that interest me a number of times already and he has not addressed them.I personally would not limit this thread to jar. I don't even see what he's trying to do. Spend this entire thread in some kind of preparation before he "gets to" my questions? Hey, I wrote the OP, and that's not what I asked for.If I were to choose anyone to participate here I might choose Coragyps, possible jazzns.Edited by Faith, : No reason given.Edited by Faith, : No reason given.Edited by Faith, : No reason given.

Stop accusing me of "seeking" creationist rebuttals when I've specifically said I want to avoid that. If people ask me questions there may be no way to avoid them. That's what I've said.I'd say leave the thread alone. It may be a mess but we're in the business of defining it and it may sort itself out with the clarifications that have been getting stated.

Totally condescending and patronizing, but I don't care about that. The problem is he's not addressing what the OP was about, and wants to lead me down some long winding trail of preparatory ideas of his own choosing that don't seem to me to be at all related to the purpose of the thread, and that I already know quite a bit about.

If jar wants to lead this and others want to contribute to what he's doing, that's fine.THE MAIN THING FROM MY POINT OF VIEW IS THAT I WOULD REALLY LIKE TO TAKE A BACK SEAT, just go along for the ride, not be asked questions, but ask them myself if I may.Edited by Faith, : No reason given.

That would probably help get us started. I hereby delegate kuresu to be the official student on this thread.You can get the thread rolling by addressing questions to anybody of your choosing I would say, jar or jazz or coragyps or all three. Maybe in fact the three of them would be a good group of teachers for the thread.And I can read along and ask questions myself when I have them.

Percy, you ARE accusing me, both of seeking debate and seeking offense, and this is false and unfair. I told you I was answering the question. I had to correct my earlier answer. THis is not seeking a debate, this is answering questions, and I was claer about that. Jar asked a bunch of totally irrelevant questions instead of addressing the OP and I answered them and had to correct one of my answers. STOP ACCUSING ME!!! Jar's questions wanted to know if I could agree with his list of propositions. Well I don't agree with them. What do they have to do with the OP anyway? Why don't you call jar on his hijacking of this thread?Edited by Faith, : No reason given.Edited by Faith, : No reason given.

Thank you Jazz for actually addressing the questions in the OP and to the others who have done so as well. Your answers are sensible but too general for what I had in mind. I think really there is no answer to my question. I want to be able to visualize this process for all locations on earth and I need to be able to get a sense of the actual process in some specific locations to get an idea of it, but really, I think I was asking too much, and maybe it's a good thing this thread has become a basic geology course instead.Edited by Faith, : No reason given.