How the geo strata are identified as time periods

Just a few points I hope you will respond to.

1. unless there are signs that the area has been disturbed, a layer under another layer is likely older than the layer above?
2. by looking at the structure of a layer it is possible to get an idea of how it formed?
3. generally, unless there is some obvious other explanation, a thicker layer took longer to build up than a thinner layer of similar composition?
4. that layers which are made up of sediment require some other higher source be eroded to provide the material?
5. that obvious signs of missing layers indicate that material was worn away?

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Aslan is not a Tame Lion

to which Faith replied:

quote:

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Sounds reasonable, depends on what this means in practice.

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So let's look at that in some detail.If you found a layer that was made of small individual parts that were somehow conglomerated into rock, what conclusions do you think you could draw?What questions might you ask?

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Aslan is not a Tame Lion

Which I hope is where we will get, if not in this thread then in the followup thread.AbE:The idea of the fossils and all will come later, just as it did in real life, as well as well as absolute dating. I'd like us to start off with some of the basics just as the folk did who initially determined first relative ages and then absolute ages. The absolute age question though can a long long time after the relative ages was determined.For example your issue with thickness of a layer vs time is a great question and we WILL get to that.Edited by jar, : add material

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Aslan is not a Tame Lion

Faith, I'm not at all sure that I am going to be able to help but am more than willing to try to answer your questions. If you would like we can step through this as I suggested, but it will be a long, slow process I fear.I really know no other way to do it and cannot give you the answer in a 30 second spot. I promise though that I will try NOT bring up the flood. I will talk about how things are made.If you want to continue I am more than happy to spend the time with you and call in others with far more knowledge than me when needed. For the most part though I, like you, am but an amateur and so it is possible that if you walk awhile with me I just may be able to explain things in a way that is less technical. The folk that really know this stuff will love to jump in though and straighten me up when I make to gross a mistake or even more likely, when I over simplify.

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Aslan is not a Tame Lion

The other folk will, I'm sure have lots to contribute but let me start with what is called clastic sedimentary rocks. They make up a bunch of what we see in the field. Clastic sedimentary rocks are made up of smaller individual pieces. You can tell a lot about them from just looking. For example they might be made up of small pieces or bigger pieces, they might be sorted or not sorted. In addition just by looking at the pieces you can get an idea of how far and long they wer transported.Here are some basics.Little pieces used to be big pieces.The smoother the pieces are the more they were transported and tumbled.You can see an example of size sorting and what causes it here.And here are some examples of wear and roundness with an explanation of what causes it.

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Aslan is not a Tame Lion

There is one other question I'd like you to consider.How do you get clastic sedimentary rock?

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Aslan is not a Tame Lion

Well, I'm trying to stay in the background pretty much but I think this is important because it shows the reasoning that led to the idea of a Young Earth only 6000 or 10,000 or even 1000,000 years old being discarded long before we could do any absolute dating.The important thing is that Clastic Sedimentary rocks are made up of other rocks. They began life as something else, igneous or metamorphic or other sedimentary rocks or often a combination of all those. They began life somewhere else, were formed, then were worn down, disturbed, moved to where they are now and then transformed. A short lesson plan is here

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Aslan is not a Tame Lion

Well, it will likely come up but only in the lowercase fashion, water as one of the transport and shaping methods. I don't see how we can get around it and still describe some of the things seen.

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Aslan is not a Tame Lion