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Zenmaster6

What does this mean?

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Zenmaster6

When walking along titlow beach in WA (Eocene time period) and we find coal buried in the side of a cliff. Does this mean there was a plant there? bacteria? Tree bark? How did this get here?

Also when walking along a Covington river far from the ocean in WA, we find a perfect stripe of coal on the side of a sedimentary rock wall. We can dig it out and it goes back very far. Does this mean that it was the 

bottom of a lake, ocean or forest where plenty of plants died and were covered in sediment? How did this coal even get here. Does this mean there might be fossils nearby? 

 

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Peat Burns

I wonder if it is charcoal and indicative of a forest fire at that stratigraphic interval.  How hard is it?

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ynot

Coal is formed when plant material is buried and heated while under pressure from the overlying sediment.

Often the environment of the plants was a swamp or a peat bog, where a lot of plant material piles up over many years, but a single piece of wood or other plant material can become "coal".

 

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Zenmaster6
20 minutes ago, FranzBernhard said:

I like this stuff, don´t know why...

 

 

The occurrences you have shown don´t look like continuous coal seams in the strict sense (buried, forested swamps or peat bogs).They are more likely individual pieces of wood that have gotten coalified. These pieces can still be called coal. Such pieces can accumulate in a lake environment, but also in a marine environment (driftwood).

@ynot already pointed it out :).

 

The rank of your pieces could be sub-bituminous or bituminous (they are both black). Sub-bituminous coal gives a brown powder, bituminous coal a black powder. From a coal petrographic point of view, these are all "Vitrain" (Fragments of coalified wood).

 

Are these pieces very brittle or somewhat tough? What happens, if you let them dry out?

 

Yes, there can be fossils associated with it, especially plant fossils (leafs). 

 

Franz Bernhard

The photos I showed I think are not just an individual piece of wood. Of course the one at the ocean was in the clay cliff, but the long strings on coal at the river were around 100 feet in length and curved. When I dug them out they are shiny and very smooth and the coal went back very far into the rock. Scratching them on a white rock and paper gives a pitch black color. 
They went into my carbonized wood collection. You can see how much shinier and refined they are compared to the coals next to them. Which leads me to imagine these are not just pieces of wood but rather a collection of many plants that were compressed together. Totally could be wrong though. I just have a hard time imagining wood turning into shiny perfect coal in under 50 million years.

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Zenmaster6
1 hour ago, Peat Burns said:

I wonder if it is charcoal and indicative of a forest fire at that stratigraphic interval.  How hard is it?

Very hard. Almost rock like. Of course real coal. it does burn.

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Ludwigia

The one at the river must have been a bog, then.

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FranzBernhard
8 hours ago, Zenmaster6 said:

the long strings on coal at the river were around 100 feet in length and curved.

That´s a total different story, that´s indeed a small seam.

 

8 hours ago, Zenmaster6 said:

Scratching them on a white rock and paper gives a pitch black color. 

This points to bituminous coal. Try do rub the streak with another piece of white rock (make a very, very fine powder).

 

8 hours ago, Zenmaster6 said:

Which leads me to imagine these are not just pieces of wood but rather a collection of many plants that were compressed together. Totally could be wrong though.

No, you are very probably correct :). You can both have side by side: Individualized wood fragments and plant parts compressed together. What is somewhat strange is, that this plant parts could also be exclusively be wood fragments, bark or plant stems, compressed together. However, petrographic examination under reflected light on polished sections would be needed to distinguish this vitrinite components from inertinite or liptinite.

https://en.wikipedia.org/wiki/Maceral

For a definition of coal components.

 

Individual wood fragments tend to have conchoidal, smooth fractures, whereas normal coal is somewhat more splintery, platy, flaky, angular breaking (at the same rank), like the piece in the center of your first pic. But it depends strongly on the amount of tectonic overprint, how coal fractures.

 

8 hours ago, Zenmaster6 said:

I just have a hard time imagining wood turning into shiny perfect coal in under 50 million years.

No problem, I have the same here in Austria, just 20 million years old :).

 

8 hours ago, Zenmaster6 said:

Very hard. Almost rock like

Good! What are the two pieces in the middle of your last pic?

 

Btw, you are very investigative, that´s good.

 

Franz Bernhard

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Zenmaster6
8 hours ago, FranzBernhard said:

That´s a total different story, that´s indeed a small seam.

 

This points to bituminous coal. Try do rub the streak with another piece of white rock (make a very, very fine powder).

 

No, you are very probably correct :). You can both have side by side: Individualized wood fragments and plant parts compressed together. What is somewhat strange is, that this plant parts could also be exclusively be wood fragments, bark or plant stems, compressed together. However, petrographic examination under reflected light on polished sections would be needed to distinguish this vitrinite components from inertinite or liptinite.

https://en.wikipedia.org/wiki/Maceral

For a definition of coal components.

 

Individual wood fragments tend to have conchoidal, smooth fractures, whereas normal coal is somewhat more splintery, platy, flaky, angular breaking (at the same rank), like the piece in the center of your first pic. But it depends strongly on the amount of tectonic overprint, how coal fractures.

 

No problem, I have the same here in Austria, just 20 million years old :).

 

Good! What are the two pieces in the middle of your last pic?

 

Btw, you are very investigative, that´s good.

 

Franz Bernhard

There was flakey carbon and hard rock like carbon. Someone above mentioned a Bog, later that day I found what I believe is bog iron down the road. 

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FranzBernhard
6 minutes ago, Zenmaster6 said:

There was flakey carbon and hard rock like carbon.

Seems you have both types! How does the hard, rock-like coal behave?

 

7 minutes ago, Zenmaster6 said:

Someone above mentioned a Bog, later that day I found what I believe is bog iron down the road. 

The bog that was mentioned has gone since 50 million years.

In the picture I can see some recent limonitic deposits. These can be associated with a recent bog, but not necessarily. Many other options for these formations.

Franz Bernhard

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Zenmaster6
29 minutes ago, FranzBernhard said:

Seems you have both types! How does the hard, rock-like coal behave?

 

The bog that was mentioned has gone since 50 million years.

In the picture I can see some recent limonitic deposits. These can be associated with a recent bog, but not necessarily. Many other options for these formations.

Franz Bernhard

well thank you for all that time you spent on my carbon post. You have vastly increased my knowledge of geology and fossils. Thank you!

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FranzBernhard
10 hours ago, Zenmaster6 said:

You have vastly increased my knowledge of geology and fossils. Thank you!

You are welcome! I am trying to give my best. And - I like coal :) (as a rock, not as a fuel, though ;)). 

Franz Bernhard

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Zenmaster6
31 minutes ago, FranzBernhard said:

not as a fuel, though ;)). 

Agreed :)

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Wrangellian

I believe it is not time that is crucial to the formation of coal, but heat and pressure. As soon as enough sediment has built up on top of the biomass, the process starts. There was a post not long ago with a link to an article about an experiment that was done to create a 'fossil' in a lab, using a dead modern lizard, to recreate the fossilization process as seen in a Mesozoic reptile from China. They subjected it to a certain amount of heat and pressure for a matter of days or even hours (I forget the exact details), and the matrix was hardened like rock and the lizard itself was carbonized. Of course, in nature these processes take longer than that, but not necessarily 50 million or more.

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