About fossils -- would you say this is true?

[YoursTrue]

By the volcanic rock above and below it. And by the fossil assemblage.

Do you understand that different critters lived at different times?

Yep.

 

[YoursTrue]

By the volcanic rock above and below it. And by the fossil assemblage.

Do you understand that different critters lived at different times?

Yes but the rock...the rock...the soil that's enmeshed in the fossil. That's what is tested for the date of the fossil, isn't it??

 

[Subduction Zone]

You sure?

Think so. Yep, water is wet.

 

[Subduction Zone]

Yes but the rock...the rock...the soil that's enmeshed in the fossil. That's what is tested for the date of the fossil, isn't it??

No. The fossils themselves cannot be dated usually.

Think of it this way. You have a layer of ash. Then on top of that a layer of sedimentary rocks. Then on top of that another laayer of ash.

Do you understand that the bottom layer of ash has to be older than the layer with the fossils and the layer of ash above has to be younger than the fossils?

 

[Subduction Zone]

Yep.

Good. Then you should know that if you find the critters that were lived when one fossil bed was formed and you found another one on the other side of the Earth, but with the same critters that they would be of the same age, right?

 

[YoursTrue]

No. The fossils themselves cannot be dated usually.

Think of it this way. You have a layer of ash. Then on top of that a layer of sedimentary rocks. Then on top of that another laayer of ash.

Do you understand that the bottom layer of ash has to be older than the layer with the fossils and the layer of ash above has to be younger than the fossils?

That's what I'm saying kind of, because who knows when and from where the soil came to be where they found the fossil? could have come from deep within the earth, or blown there. The soil, I presume, must be older than the bone anyway.

 

[YoursTrue]

@Subduction Zone -- Hello, here's what I said and I don't think I understood your answer. I said "the soil that's enmeshed in the fossil. That's what is tested for the date of the fossil, isn't it??" To which it seems you answered no, please clarify if you will, and then we'll go on to the rest of your comment, please. Thank you again.

 

[Subduction Zone]

@Subduction Zone -- Hello, here's what I said and I don't think I understood your answer. I said "the soil that's enmeshed in the fossil. That's what is tested for the date of the fossil, isn't it??" To which it seems you answered no, please clarify if you will, and then we'll go on to the rest of your comment, please. Thank you again.

No. That is not what is tested. That is your misunderstanding.

 

[Subduction Zone]

That's what I'm saying kind of, because who knows when and from where the soil came to be where they found the fossil? could have come from deep within the earth, or blown there. The soil, I presume, must be older than the bone anyway.

It is not "soil". It is sediment. And volcanic ash is easily identified.

Here is a picture of a volcanic ash deposit:

It looks quite different than other sedimentary rocks.

Where it is really noticeable is when one takes a " thin section " of it. A piece is cut with a saw, and then ground down so that only a very thin piece of it is left. Then geologists examine it under a special microscope.

Here is some limestone in the same sort of microscope:

 

[Subduction Zone]

@YoursTrue , knowing what country you lived in could let me show you some examples of outcrops that you could look at yourself.

 

[Subduction Zone]

This is a thin section of shale.

 

[Subduction Zone]

Here is an image of cross polarized sandstone. There are not many images like this because it is rather boring:

 

[Subduction Zone]

When geologists make and examine thin sections they do so using a cross polarizing microscope. If you are used to polarized sunglasses you will know that if you orient two lenses at ninety degrees to each other that you will block all light.. That is what a cross polarizing microscope does. It has two polarizers at 90 degrees to each other. The thin section goes in between the two. Different minerals rotate different frequencies of light different amounts. That is why a drab colorless sample can be so colorful. Except for quartz. It tends to transmit all frequencies the same. No pretty colors. So sandstone is usually quite boring.

 

[YoursTrue]

@YoursTrue , knowing what country you lived in could let me show you some examples of outcrops that you could look at yourself.

What difference would it make, because I'm interested in the dating process & how the initial dating is begun when looking for dates these fossils came from. It's obvious that if these fossils landed in lava or ash then the dates would reflect the date of the soil/strata/lava/ash they were infused with.

 

[YoursTrue]

When geologists make and examine thin sections they do so using a cross polarizing microscope. If you are used to polarized sunglasses you will know that if you orient two lenses at ninety degrees to each other that you will block all light.. That is what a cross polarizing microscope does. It has two polarizers at 90 degrees to each other. The thin section goes in between the two. Different minerals rotate different frequencies of light different amounts. That is why a drab colorless sample can be so colorful. Except for quartz. It tends to transmit all frequencies the same. No pretty colors. So sandstone is usually quite boring.

ok.

 

[Subduction Zone]

What difference would it make, because I'm interested in the dating process & how the initial dating is begun when looking for dates these fossils came from. It's obvious that if these fossils landed in lava or ash then the dates would reflect the date of the soil/strata/lava/ash they were infused with.

You have been repeatedly asking the same question. The fossils are not dated. So it does not really matter what material enters them.

 

[Subduction Zone]

ok.

I gave you a few pictures to look at. You can see that the mineral in the ash are very angular. And there is not very much quartz in it at all. The limestone is made up of small bits of what used to be living creatures. It can be rather pretty. The shale is just very fined grained clays, but again, you can seen some interesting colors, but the pieces are very small. Some of the pictures had a scale on them too. The sandstone was rather boring. I could find more for you. Do you understand now that by looking at the rocks they can be identified and that we can tell where the various sediments came from?

 

[YoursTrue]

You have been repeatedly asking the same question. The fossils are not dated. So it does not really matter what material enters them.

Ok so the fossils are not dated. The surrounding sediment is, right?

 

[Subduction Zone]

Ok so the fossils are not dated. The surrounding sediment is, right?

Usually layers above or below, or sometimes even "within". For example an ashflow can be a quick local; event. Any fossil live in the way of it would die, but one would not need to go that far to find life unaffected. Geologically, or even biologically life can be reestablished before there are any evolutionary changes. So We could "date" all of that current fossil assemblage. We would know that if we saw the same fossils anywhere else in the world in layer of sedimentary rock that it was the same age. That fossils or the sediments that they are buried in are not dated, unless some life is actually buried in the ash itself.

 

[YoursTrue]

Usually layers above or below, or sometimes even "within". For example an ashflow can be a quick local; event. Any fossil live in the way of it would die, but one would not need to go that far to find life unaffected. Geologically, or even biologically life can be reestablished before there are any evolutionary changes. So We could "date" all of that current fossil assemblage. We would know that if we saw the same fossils anywhere else in the world in layer of sedimentary rock that it was the same age. That fossils or the sediments that they are buried in are not dated, unless some life is actually buried in the ash itself.

all right. Let me give you an example. I've seen pictures of bones within a cave. Seemingly on the floor of the cave. So how is a date arrived at?