27 July 2012

Amazing facts about the Carboniferous

 

Yesterday, this headline at Reddit caught my eye:
TIL, upon the advent of wood [400mya], it took fungi 50mil yrs to evolve a way to decompose it. Until then, wood just piled up, never to decay. It is this single fact that led to the Carboniferous period [BBC doc.]
That was the first time I had ever heard of this, so I browsed through the BBC video above (it's good, with excellent production values).  The Carboniferous is discussed briefly at about the 28 minute mark, but not in detail.

I found those sentences to be absolutely stunning, and couldn't get out of my mind the image of a never-decaying forest.  I should mention here that one of my "hobbies" for years has been clearing underbrush in woodland in northern Minnesota.   I can't conceive of the tangled mess that would accumulate if no fallen wood decayed for even a thousand years.  Then extend that to millions of years...

And think of the fire hazard.  Nobody in Colorado or California needs to be reminded of the risk of accumulated deadwood.  Plus, the atmosphere in the Carboniferous had high levels of oxygen (in part because that wood was not decaying).

Today, a geology student added to the Reddit thread some confirming and explanatory notes:
1) This period of elevated oxygen levels (30-35%, versus the 21% of today) lasted from the Carboniferous through the end of the Cretaceous, 65M years ago. It is extremely likely that the large-type dinosaurs simply cannot exist in our current atmosphere. They probably needed these increased oxygen levels to reach the energy production density that these massive creatures are estimated to require.

2) It is because of A) These elevated oxygen levels, and B) the lack of a fungi capable of breaking down lignin, the structural molecule of plant material, that forest growth back in the day was completely rampant. A very large amount of the solid biomass preserved in the entire fossil record came from this one 65-ish million year timespan.

3) Nearly all of the coal beds we exploit today came from the Carboniferous and the other periods with elevated oxygen levels. Guess what? Most of the coal has been judged to have been originally deposited as charcoal. Here's the kicker. Most of the solid biomass from the time period is believed to have lived in wet marshes/semi-permanently raining rainforests. Coal beds from the same (originally rainforest) bed formations have been found on continents separated by entire oceans. Some of these beds have been hundreds of meters thick. These factors imply that global-scale firestorms were a very common occurrence during the Carboniferous, and that these fires occurred in very wet conditions that would be simply impossible during the modern day. This and the lack of a fungal decay mechanism (also, charcoal basically cannot be broken down by fungi even today) is why so very much coal comes from the Carboniferous.

4) This here is the cool piece of information. The Cretaceous ends, geologically, at something called the K-T boundary, which is the few-millimeter thick layer of space dust that marks the Yucatan Peninsula impact. As most of you know, a rare platinum group element, iridium, is found in this thin layer (Iridium is only found in decent amounts in asteroids...). But, recently, investigators have found that a very large amount of soot is also in this layer, to the tune of several weight %. One investigator did some simple projections and calculated that the deposition of this amount of soot worldwide would imply that 25% of the entire biomass of the planet Earth burned after the meteor strike. The asteroid has been found to have caused a global firestorm, a holocaust in the truest sense of the world - one that would not have been possible were it not for the elevated oxygen levels
There's more at the link.

In this blog I do try to be tolerant of different viewpoints, especially religion-based ones.  I will sometimes express incredulity or speak out against intolerance, but I do try not to mock - except for "young-earthers."  And when I post something like this, I actually have to kind of feel sorry for them - that their worldview cuts them off from some of the most magnificient and spectacular concepts that the mind can encompass.  I'm going to be thinking about the Carboniferous and Cretaceous forests and firestorms for a long time.

20 comments:

  1. In the western U.S., coal comes from Cretaceous swamp and peat deposits. And these deposits predate the K-T event. They're not charcoal. And future coal seams are being created today in peat deposits that are resistant to fungal and bacterial decay for chemical and climatological reasons. The Carboniferous was very different, but it does not contain "nearly all coal that we exploit today".

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    Replies
    1. Do you have a source for your claim that the western US coal was not deposited as charcoal?

      I'm also not seeing where the post claims that "nearly all coal that we exploit today" came from the Carboniferous alone. The claim was that it comes from "the Carboniferous and the other periods with elevated oxygen levels".

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  2. This whole post is amazing. Thank you!

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  3. My mind is blown. This certainly is fuel to the imagination...

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  4. Magnificent!

    What, indeed, could these forest quagmires have looked like? Piles of logs hundreds of feet thick, with trees growing out of trees out of trees, with bizarre species scuttling about in a dark maze underworld - only to be all turned to charcoal in some amazing inferno...

    All the forgotten spectacles this earth has hosted! Super discovery.

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    Replies
    1. Imagine also that the trees were predominantly gametophytic (a dominant gametophyte (n) generation - the sporophyte generation (2n) was microscopic). Today, trees are sporophyte dominant (the gametophytic generation is microscopic), and of indeterminant growth. Then, huge club moss-like trees that grew to a genetically predetermined height, spread their spores, then died. The wood could not grow new phloem, therefore could not increase in girth, and had a pith through the height of the tree.
      Also imagine with the oxygen-rich atmosphere, the giant insects that thrived, and dominated. They could probably do shots of DEET all day.

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  5. I won't pretend to understand much of this but this is why I follow this blog. It stretches my brain.

    PS: Haven't stopped reading, just haven't commented in a while.

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  6. Immanuel Velikovsky?
    Worlds in Collision?
    Try it with a basketball.

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  7. Fascinating. Now can someone please tell me where oil comes from? I have read that it comes from dead animals and plants, I believe, but that boggles my mind. Why is so much of it in the desert, which probably wasn't desert at some point?

    That would be an interesting follow-up to this, Stan.

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  8. Really sorry to be the party-pooper, but this seems to be absolute nonsense. 50 million years of no decaying wood? I've seen what the forest floor looks like after one tornado, it this were to only happen once every 250 years for 50 million years, it would seem impossible for anything to get to the soil to even germinate. And if woody material isn't decaying for mulch, how are the soil nutrients being replaced anyway? And if global fires are creating massive coal mines on the surface, how does anything grow in that?

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    1. A) Tree seeds don't need to get to the soil to germinate. They can grow on top of, or from the crotches of, other trees.

      B) Tree don't suck their sustenance from the soil - they grow "from the top down" - taking CO2 out of the air to make their cellulose.

      C) Charcoal is an excellent nutrient and growing medium. Look up "terra preta" to see how primitive people added charcoal to dirt to farm the Amazonian region.

      And, you're forgetting (or ignoring) the cleansing effects of the forest fires. That forest floor you've seen after one tornado - think of how that area would look after a firestorm. You could ride a bicycle through it.

      But I think these trees were mostly like cycads, and grew in swamps.

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    2. Hrmm...I'm still a skeptic. For A) I'd say that there would still have to be some soil or mulch on top of or in the crotch of a tree for a tree to take root, but maybe the leaves decompose but not the wood?

      B) They have to at least get water from the soil. Where do they get nitrogen from? Maybe trees do not need nitrogen like other plants?

      C) I wasn't thinking of a charcoal mix, I was thinking of gigantic slabs of coal that would be like solid rock. Maybe I have the picture wrong in my mind.

      Finally, I guess I am just having trouble picturing a "swamp" that has several thousand feet of tree lumber stacked in it. I need an illustration!

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    3. You're skeptical because you don't understand, yet you seem to speak like you not only understand, but know for a fact what plant life was back then.

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  9. Breaking down lignin is one of the key challenges for the biofuel industry; it took nature 50 million years to find a way through lignin...

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  10. This comment is dead on "And think of the fire hazard. Nobody in Colorado or California needs to be reminded of the risk of accumulated deadwood." I totally agree.

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  11. Wow. I love this blog for finding gaps in my knowledge. Always interesting!

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  12. Used tubechop to grab the relevant portion.
    http://www.tubechop.com/watch/472633

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  13. Updated location chopped:

    http://www.tubechop.com/watch/1314118

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    Replies
    1. I've updated the post using your new chop as the embed. Thanks, Faraday - I hope this one lasts for a while.

      Delete

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