[neilep (OP)]

Shhhhhhhhhhhhhh !!

tread carefully cos this piece of wood is very nervous !!

It's petrified !!.....*le lame et le groan*


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What is petrified wood ?......what other things gets petrified (ala wood) ?

[Karen W.]

It is wood that has over time hardened to become rock like! I have some somewhere left from ,my rock collection! They are actually very prety! anything that was in the wood is petrified.

I often wondered why it did not rot or deteriorate like most woods do over time and why certain pieces remain and petrify!

[DoctorBeaver]

It's not nice to eat  [xx(]

[Andrew K Fletcher]

When a tree dies in a dry climate like a desert, the circulation does not stop as proven by Strasburger et al. I put forward an explanation for this continued flow, relating it to the process of decay releasing minerals to flow from the top of the tree to the bottom, in doing so creating a circulation effect driven by the differences in density, as shown on the video's on metcafe titled the gravity of life.

This process will inevitably continue and the high evaporation rates in the desert conditions coupled with occasional bouts of rain would continue to release the salts down the trunk until they are concentrated in the lower part of the trunk and roots. The top half of the tree would become severely weakened by the washing out of materials from the upper part of the tree causing it to decay or break off and decay, but the bottom half of the tree would have become stronger and over many years much stronger as the salts fossilized under the harsh conditions.

Anyone got a better explanation?

[Alandriel]

I've got a piece of petrified bamboo in my rock collection!

Very  [8D]

When we lived in Egypt we used to drive out a couple of hours out of Cairo to a petrified wood forest in a dry wadi. One of the coolest places I've ever seen in my life. Tons of stuff just lying around - I think the place is now all built up  []

other than that


petrified banana  []

[Karen W.]

Here are a few shots of my petrified wood It was found in New Mexico in 1950 by me Grandma who wrote on it where she found it and the date it was found. It is quite a pretty piece! I wonder what kind of wood it was?













 They are not perfect shots but it is 4:05 am.

[Alandriel]

Could be anything Karen.

Mexico has many diverse climate/vegetation regions (though it does remind me of my acacia piece)
Can you read the name where your grandma found it?
Maybe we can make an educated guess.

4.05am  [] what are you doing?!?!?!

[Ophiolite]

Anyone got a better explanation?

After a tree has fallen and is buried in sediments minerals replace the organic material. If this occurs slowly enough much of the original structure of tree will be preserved.

Andrew, your explanation, while charming, bears no relationship to reality.

[JimBob]

Anyone got a better explanation?

After a tree has fallen and is buried in sediments minerals replace the organic material. If this occurs slowly enough much of the original structure of tree will be preserved.

Andrew, your explanation, while charming, bears no relationship to reality.

I will second Ophiolite's explanation. It occurs in wet conditions when buried because the minerals that actually replace the cellular structure of the wood are carried by the water in a very weak solution. I have some petrified palm wood from a few miles east of here that I have cut perpendicular to the length that has such detail parts of the cells can be seen in thin section.

(Take a 0.25 cm slice of rock, mount it on a slide, grind it until it is transparent and place a cover glass over it so you don't damage the microscope lens and - Presto!, a thin section)
 

[Alandriel]

But Andrew remains charming.... [] []

..... and neil of course too  []

Thanks folks - I learnt yet another interesting thing from you.

Take a 0.25 cm slice of rock, mount it on a slide, grind it until it is transparent and
place a cover glass over it so you don't damage the microscope lens and - Presto!,

Now I just wish I had a rock slicer, a grinder and a good microsope.

Would love to see what that looks like

[Karen W.]

Could be anything Karen.

Mexico has many diverse climate/vegetation regions (though it does remind me of my acacia piece)
Can you read the name where your grandma found it?
Maybe we can make an educated guess.

4.05am  [] what are you doing?!?!?!

Looks like c e n  and maybe i s also. I know she lived in Gallop and Farmington is where my Auntie lived! It is hard to make out the city .

Well as usual Posting in here cause I can't sleep! LOL

[Andrew K Fletcher]

I have seen many trees fallen and watched over the years as they have rapidly decayed, which I might add one would expect to happen. Some have fallen in rivers, some have fallen into marshes and some have fallen onto relatively dry land, all resulting in fairly rapid microbial decay. Oddly enough this happens to corpses also, except for the one that fell into a peat bog and got tanalised over time.
Having utilised a log burning fire for a few years now I have also watched the seasoning of logs in a dry environment exposed to UK rainfall and can add that the logs are decaying still but a little more slowly. Another interesting observation with logs stacked vertical is that the tanin leaches out and stains the concrete, caused by rainfall washing the minerals out of the vertical tubes in the timber.

But there are exceptions to this rule when the decay occurs in a dry environment. Mummified remains found preserved perfectly in one of the driest places on Earth.
 http://www.extremescience.com/DriestPlace.htm
Now these corpses are thought to be around 800 years old. What is preventing the decay? Certainly not the sedimentary deposits you suggested. Sediments after all require water. Microbes require water and decay requires water, whereas preservation requires sterility rather than decay poses us with an intriguing puzzle as to why these often huge tree specimens did not fall victim to the moulds and fungi? Perhaps the answer lies in the everglades as this would provide sediment and falling trees. But I bet you a pound to a pinch of salt you won’t find any fossilized trunks there either. I have erected fencing which has been treated many times and sank into a whole range of aggregate and soil only to find the stumps rotting away over a few years.

Something must have changed that killed off the bacterium and fungi that caused the rapid decay we see in trees today. I believe this was the lack of rainfall caused by stripping the vegetation from around the coastlines and creating the same thermal barriers we see in place on desert coastlines today. No rainflall = desiccation of life and sterilization over time has caused these huge trees to be preserved not sediment deposits.

Maybe if we could find evidence that the trees became fossils while standing not falling over as you stated we might settle this argument?
5.Pinoxylon paradoxum SUSS & VELITZELOS (sp.nov.) Standing fossilized tree trunk, 1.28 m in height, in the the Petrified Forest park at «Pali Alonia». The considerable frequency of fossilized tree trunks preserved standing with their root systems fully developed confirms that they were petrified in situ
http://www.aegean.gr/petrified_forest/Frames/HTML/English/photos.htm#photo5

Anyone got a better explanation?

After a tree has fallen and is buried in sediments minerals replace the organic material. If this occurs slowly enough much of the original structure of tree will be preserved.

Andrew, your explanation, while charming, bears no relationship to reality.

[Ophiolite]

Preservation of any organism as a fossil is a rare occurence: most of the time, most organisms leave no detectable trace after death. this is especially treu for organisms with no mineral skeletal structure. So plants and trees are extra hard to preserve.
You are therefore correct that special conidtions are necessary for a tree to be fossilised. Note that we do not require the wood to avoid decay, only that the mineralisation of the wood should occur at a faster rate than the decay.
You have mentioned a dry environment as one where decay can be avoided or at least delayed. Immersion in volcanic ash is another - this happened in the petrified forest of Lesvos. Or immersion in anoxic conditions - there are timbers on the floor of the Black Sea that are probably thousands of years old.
Finding an occasional example where the stump of a tree (six feet tall in your example) is preserved upright does not invalidate the mechanism. In general we believe that the trees fall and are submerged in sediment, but teh key word here is submerged. It is entirely possible in flood conditions for a massive amount of sediment to be deposited around a tree whose upper portion has been broken off.
In the desert east of Cairo there are square kilometres cvovered with the fossilised remains of a forest of trees, all lying flat on the ground. (I am looking at the fragment of one on my window sill as I type.) This is how the majority of trees are fossilised.

[Alandriel]

This is all extremely interesting  [] I really like your input Andrew  []

In the desert east of Cairo there are square kilometres cvovered with the fossilised remains of a forest of trees, all lying flat on the ground. (I am looking at the fragment of one on my window sill as I type.) This is how the majority of trees are fossilised.

Yep - that's the location I mentioned earlier. Fab place  []

The fossils might be lying around now, but knowing the topography a bit of that corner I also know it's a wadi, a dry river bed and you can very easily see many 'wash-marks' along the sides of that wadi. Once, a forest stood there. And then it got washed out, sedimented over perhaps and many many centuries later when the climate changed yet again, it dried out and the winds and flash floods carried the soil/sand away again, exposing the whole lot.

We did go digging there on occasion. There's lots more under the ground  []

[Andrew K Fletcher]

Ophiolite

I am trying to explain that the direction of tubular structure inside the tree would best trasport solutes to the trunk if it was vertical prior to fossilization. You add about the trees preserved by volcanic fall out. I have also observed these trees, some of which are still embedded in the rocks in which they were encased, and I might add are vertical.


 In Lesbos,Greece, Fossil forests have standing trees with roots! The fossil forests in Greece cover an area of 150 square kilometers.

When a tree is covered by volcanic material in situ, it obviously dies. However, the circulation inside the dieing tree continues for some time after death as solutes flow down and dilute solution flows up until all the salts have reached the lower part of the tree. Then rain over countless years washes more solutes into the vertical tubes of the tree causing more circulation to be initiated over many years until all the tubes of the tree become solidified and petrified.

The tree becomes brittle, as one would expect with rock, rather than a flexible trunk as in timber. Land movement, flood and general erosion may be responsible for many of the horizontal trees, which according to those petrified examples that are still in situe suggest. This could easily be determined by reconstructing the fall and working out the position of fallen trunk segments, which would have shattered and sperated under the impact as one would expect to happen to a falling column of stone that shatters on impacting the ground. This could explain why some trunks are found and no roots are located close to the trunk?

In areas like Greece, roots are located next to the trunk because they are in exactly the same place where petrification happened all of those years ago.

Preservation of any organism as a fossil is a rare occurence: most of the time, most organisms leave no detectable trace after death. this is especially treu for organisms with no mineral skeletal structure. So plants and trees are extra hard to preserve.
You are therefore correct that special conidtions are necessary for a tree to be fossilised. Note that we do not require the wood to avoid decay, only that the mineralisation of the wood should occur at a faster rate than the decay.
You have mentioned a dry environment as one where decay can be avoided or at least delayed. Immersion in volcanic ash is another - this happened in the petrified forest of Lesvos. Or immersion in anoxic conditions - there are timbers on the floor of the Black Sea that are probably thousands of years old.
Finding an occasional example where the stump of a tree (six feet tall in your example) is preserved upright does not invalidate the mechanism. In general we believe that the trees fall and are submerged in sediment, but teh key word here is submerged. It is entirely possible in flood conditions for a massive amount of sediment to be deposited around a tree whose upper portion has been broken off.
In the desert east of Cairo there are square kilometres cvovered with the fossilised remains of a forest of trees, all lying flat on the ground. (I am looking at the fragment of one on my window sill as I type.) This is how the majority of trees are fossilised.

[Andrew K Fletcher]

Damn, just realised something here that suggests that the trees must have been standing during petrification. First of all as suggested above the distance between each segment of the trunk indicates the tree shattered when it fell and tossed the segments apart from each other. Pretty obvious really. But more important observation is the clean snap between each segment, indicating a brittle trunk shattering rather than a tree trunk breaking which we all know would splinter.


Petrified forest on top of a hill: Many examples of very tall petrified forests in situ. On a hill way above sedimentation levels also.
http://www.nps.gov/archive/yell/slidefile/geology/paleontology/Page.htm

[Bass]

Have you ever heard of "bobby socks"?  These are trees in thermal basins in Yellowstone Park that are absorbing enough mineral (silica) to fosilize in place (I have a picture somewhere that I'll try to add).  Called bobby socks because of the white coloration of the trunk area as the tree dies (from either heat or mineral absorption).  I suspect that a similar process happens in some trees covered with volcanic ash- the trees absorb silica from the ash, possibly before the death of the tree.
Andrew, a catastrophic event can also "snap" trees without much splintering- Mount St. Helens is a great example.  I suspect much of area destroyed by St. Helens will become a "fossilized forest" in the future- with both standing and downed logs.  Several petrified forests in Eocene Absoraka volcanic rocks were probably catasrophically buried in similar climate conditions to St. Helens.
All kinds of woody material can be petrified.  I have found petrified reeds, weeds, grasses and even flowers and leaves in hot spring deposits. 
Still looking for a petrified woodpecker in the petrified forests I frequent []

[Andrew K Fletcher]

Cheers for that Bass.

Still trying to say that the vertical tubular structures of trees aided the preserving process while petrifaction took place and that solutes percolated down the tubes of the trees that stood vertical.

Has anyone done a density check on materials found inside the fossilized trees, which should show different layers from top to bottom. I know that density changes take place in the trunks of living trees, having read several papers on the findings of people working in this field. Which is where I was going with this analogy of fossilization in trees. This should fit with trees found in volcanic material preserved upright. Lignification materials should be predominantly at the bottom of the trunk, while external environmental materials should be above the lignifying deposits. I mentioned that tannin seeped out on my drive from logs placed vertical, washed out by the rain. I also mentioned the tantalising of the corpse found in the bog. Tannin is a great preservative. The death of the vertical tree would inevitably releases solutes from the canopy down the trunk to settle eventually in the lower part of the tree, weakening the upper part of the tree, but preserving the lower part of the tree. Sedimentation would then be secondary to the initial preserving effects of the trees own solutes, together with salts from the soil drawn in by the tree, which according to Strasburger et al would see circulation continuing long after the huge trees had died. This means, that even during and after death minerals and nutrients would continue to be drawn into the tree and transpiration would continue many weeks after the trees had died, possibly under accelerated inflow due to the rapid release of solutes from decay in the upper part of the tree.

Another analogy to throw against the horizontal fossilization is the lack of fossilizing wooden ships. They are after all submerged in sediment, yet become fragile and rot away. Great care is taken to lift the Mary Rose for example. The timber is very fragile.

[Bass]

Founds a photo of the lower geyser basin showing "bobby socks" trees.

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[Karen W.]

Those are cool! What a nice picture Bass!

Damn, just realised something here that suggests that the trees must have been standing during petrification. First of all as suggested above the distance between each segment of the trunk indicates the tree shattered when it fell and tossed the segments apart from each other. Pretty obvious really. But more important observation is the clean snap between each segment, indicating a brittle trunk shattering rather than a tree trunk breaking which we all know would splinter.


Petrified forest on top of a hill: Many examples of very tall petrified forests in situ. On a hill way above sedimentation levels also.
http://www.nps.gov/archive/yell/slidefile/geology/paleontology/Page.htm

Andrew this is teriffic! I have never seen these before... I have always heard about the petrified forest but never really knew weather or not this was a real place... do you?