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Author Topic: Have plants increased Earth's diameter?  (Read 2942 times)

John Richards

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Have plants increased Earth's diameter?
« on: 26/09/2011 14:01:03 »
John Richards  asked the Naked Scientists:
   
Dear Sir/Madam,

Some 500 millions years ago there were no plants on Earth.  Then plants did arrive and the Earth was covered in forests.  They rotted down (partly to form the coal measures) to create a layer many miles thick. 

Does this mean that the diameter of the Earth increased, even by a small amount, and is still increasing?  If not what compensated for the extra layer?  I would be most interested to receive your comments.

John Richards

What do you think?
« Last Edit: 26/09/2011 14:01:03 by _system »


 

Offline Nizzle

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Have plants increased Earth's diameter?
« Reply #1 on: 28/09/2011 14:09:21 »
I don't think plants increased the diameter of earth. The stuff that makes up plants had to come from earth in the first place.

Only external things like asteroids that crash down on earth might increase it's diameter. Especially very big ones with a lot of ice in them
 

Offline CliffordK

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Have plants increased Earth's diameter?
« Reply #2 on: 28/09/2011 18:19:25 »
That is what my thoughts were.  The soil, minerals and nutrients that make up plants come from the soil, and return to the soil.

The plants do remove carbon dioxide from the air.  While some of it is part of a carbon cycle, some of it does get trapped for a long period.  So, one might be able to think of trapped atmospheric gasses giving a very minimal increase in the size of Earth's crust.  Obviously the total mass of the earth + atmosphere would stay the same, at least with respect to plants matter.
 

Offline Don_1

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Have plants increased Earth's diameter?
« Reply #3 on: 04/10/2011 13:26:10 »
I'm not sure I would entirely agree with you there Nizzle & Clifford.

Yes, it is true to say that the plants and trees are a reconstruction of already existing minerals, but, as you wrote, Clifford, there are gases from the atmosphere mixed in with the minerals from the soil. This would also be true of animal bodies. The early Earth's atmosphere consisted of many more gases than it does today. These gases (methane, ammonia etc.) have been locked away in the Earth's crust in forms such as coal, oil and gases trapped in porous rock.

Take the minerals and water which make up a tree and you will find that they have less volume as separate constituents that they do as a whole tree. Of course the tree will die and turn back to these individual constituents, but that process might take a hundred years or more to complete.

So I would say that as a baron watery rock our planet would have been smaller than it became after the trees and other plants colonised the land and began to die off, leaving an inflated soil level.

Maybe I am being a little pedantic, since I would have to agree that any difference might not have been any more than a 1 or 2% increase in the overall size of the planet.
 

The Naked Scientists Forum

Have plants increased Earth's diameter?
« Reply #3 on: 04/10/2011 13:26:10 »

 

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