[traveler (OP)]

Has anyone heard about this theory? It seems plausable but I don't have nearly enough knowledge to make a decision on it. This link has a lot of information about the theory. Is it possible or is it another "convienent truth"
http://www.expanding-earth.org/ [nofollow]

[imatfaal]

I am really not a geologist of any kind - but it smells of high-grade hokum to me

[CliffordK]

You can read about The Gondwana theory here.  The timeline seems to be similar with the continental drift theory. 

I'm seeing estimates that the earth is currently getting bombarded with about 10⁷ to 10⁹ kg of meteorites per year.  It sounds like a lot...  but divide that by a thousand, and one gets on the order of 10,000 to 1,000,000 metric tons per year.  Consider that the coal mined each year is measured in the billions of tons, or several thousand times that amount.

Anyway, over a billion years (10⁹), the earth will expand by about 10¹⁶ to 10¹⁸ kg.

Now, let's consider the Mass of the Earth, about 5.9736×10²⁴ kg, with a factor of about 10¹⁵ to 10¹⁷ difference.

Let's divide that by a billion years (10⁹), and one gets somewhere between 10⁶ and 10⁸

So, at the current accretion rate, over a billion years, the Earth would have expanded by a fraction of about 1/1,000,000 to 1/100,000,000. 

Now, let's consider the mass of the oceans at about mass of the oceans is approximately 1.35×10¹⁸ metric tons (1.35×10²¹ kg)

So, over a billion years, the mass of the Earth would have increased by somewhere between 1/1,000 & 1/100,000 the mass of the oceans (not all being water, but it makes a handy comparison).

Obviously accretion rates may not be constant, and we could be in a minimum now.  There are theories that Earth goes through cycles of heavier meteorite bombardment every few million years.  However, one would conclude that over the last billion years, Earth might have expanded by somewhere on the order of a meter due to meteorites. 

So...
What causes sedimentary deposits?

What about volcanic activity, and redistribution of soils due to erosion.  Volcanic activity, of course, involves the movement of subsurface minerals to the surface, with subsidence of the surface to compensate, and no net increase.

The article discusses oil wells.  Consider an oil well at less than 3 km deep, and 100 to 200 million years old.  What if that was all "new deposits".
Then, let's try some calculations.
Volume of a sphere, (4/3)πr³
So, the difference in the volume between two spheres would be  ((4/3)πr₁³) /  ((4/3)πr₂³) = (r₁/r₂)³

If the current radius of the Earth is 6,371.0 km, then we get a growth of less than  (6,368/6,371)³ =  0.9986, or about 0.14% over the course of 100-200 million years for a 3 km deep well (this, of course, ignores sediments from volcanoes and erosion).

Even a couple percent difference in the mass would not cause a rapid increase in the accretion rate.

There is debate about the hydrogen balance.  Earth will pick up some new hydrogen from the solar wind and cosmic rays, but this also may knock some atmospheric elements away.  Earth, however, can not hold onto free hydrogen & helium in the atmosphere.  It may even have troubles holding free water vapor (but not condensed water).  Anyway, it is likely the hydrogen balance is like in equilibrium.

With the expected future lifetime of our sun being about 4 billion years,  it is unlikely that we will have to worry about the planet growing out of control, and surpassing the size of the gas giants.

[Bored chemist]

Oh dear! not again
http://www.thenakedscientists.com/forum/index.php?topic=17097.0

[CliffordK]

Oh dear! not again
http://www.thenakedscientists.com/forum/index.php?topic=17097.0

And Here
http://www.thenakedscientists.com/forum/index.php?topic=25336.0

And Here
http://www.thenakedscientists.com/forum/index.php?topic=37030.5

[OokieWonderslug]

I find the theory intriguing. The continents do all connect up if you only remove the oceans. The entire landmass of the planet locks together if there is no oceans. And it is true that there are no truly old oceans. None older than 100 million years I think. But it can't properly account for mountain ranges, and above all there is no mechanism for the expansion. I thought I had come up with one, but apparently no one thought it would work. That being the decay of uranium into more massive elements in the core. IE decay elements being "fluffier" and taking up more space. These newer elements putting pressure on the crust and growing the planet.

[CliffordK]

That being the decay of uranium into more massive elements in the core. IE decay elements being "fluffier" and taking up more space. These newer elements putting pressure on the crust and growing the planet.

The decay would produce more (qty), but less massive elements.
Density,of course, is the key, with Uranium metal having a density about 19g/cc, and Lead having a density of about 11g/cc, and a host of other intermediaries.  Plus, Helium, and Hydrogen formed.  If one actually gets fission, one would also get lighter elements.  Of course, it would be found more in various oxides than metallic form.

Perhaps one should calculate that in moles rather than grams.
So... 
U: 238 g/mole.  ==>  (238 g/mol) / (19.1 g/cc) = 12.4 cc/mol
Pb: 207 g/mole. ==> (207 g/mol) / (11.36 g/cc) = 18.2 cc/mol

UO₂: 270 g/mol  ==>  (270 g/mol) / (10.97 g/cc) = 24.6 cc/mol
PbO₂: 239 g/mol ==>  (239 g/mol) / (9.38 g/cc) = 25.47 cc/mol

So, going from Uranium to Lead in metallic form, it will actually expand somewhat.
going from Uranium to lead in oxide form will have less expansion.

Plus, of course, the 8 moles of helium. 

Some Natural Gas deposits have up to about 7% (vol) Helium from nuclear decay origin, which is a pretty extraordinary amount.  I suppose it would depend on how much rock contributes to those levels, but each Uranium atom produces about 8 helium atoms.

But, one must ask how much Uranium is there?
This article suggests that a 5 mile ball of Uranium would be 65% of the total Earth stores.

I've also seen estimates of about 2-3 ppm in the crust.

Anyway, I think that is the problem with nuclear reactor driven expansion.  There just isn't enough Uranium decaying to make that significant of a difference in the total Earth volume, especially not on the scale to create oceans larger than land masses (not to mention where did all the water come from).

[traveler (OP)]

I had a feeling that all of you would put holes in this theory. I looked for intormation on this at another site and someone has a theory that all of Mars' water is now on Earth.

[CliffordK]

I looked for intormation on this at another site and someone has a theory that all of Mars' water is now on Earth.

Some of Mars water could have ended up on Earth.  I would hardly think all of it.

Water balance is complicated. 

If one considers noble gases, molecular weight, and atmospheric concentration.

Element	Molecular Weight	Mars	Earth	Jupiter
Helium	4	trace	0.000524%	He/H	0.0975
Neon	20	0.00025%	0.001818%	Ne/H	1.23×10−4
Argon	40	1.6%	0.9340%	Ar/H	3.62×10−6
Krypton	84	0.00003%	0.000114%	Kr/H	1.61×10−9
Xenon	131	0.000008%	0.000009%	Xe/H	1.68×10−10
Nitrogen (N2)	28	2.7%	78.084%	N/H	1.12×10−4
Carbon Dioxide (CO2)	48	95.32%	0.039445%

Anyway, the relatively low abundance of Neon on both Earth and Mars, but high abundance of Argon indicates that both Earth and Mars have troubles holding onto atmospheric gases with molecular weights less than 20, but are able to hold onto atmospheric gases with molecular weights of > 40.

Water has a very low molecular weight of about 18, so one would expect that Earth would also loose its water rather than trapping water.

However, Earth also has a "cold trap", in which the temperature drops rapidly in the upper troposphere.  The pressure also drops, but reaches a point where the temperature/pressure would force atmospheric water to condense back into water droplets or ice crystals.  The temperature increases again in the upper stratosphere, and themosphere (with lower temperature in the mesosphere).

So, what happens to molecules that are "lost"?
Presumably they would enter orbit around the sun, perhaps a slowly degrading orbit, which would then eventually bring lost Martian water into Earth's orbit.  However, only those molecules that would reach down into the troposphere would necessarily condense and fall to Earth.  There wouldn't necessarily be a huge propensity for the free Martian water to get captured by Earth, and much of it would likely just pass by Earth.  Or, some might get knocked into Jupiter's orbit.

Undoubtedly some water is gained by Earth.  Some would also be lost by Earth.

[Bill S]

The "evidence" from the Grand Canyon would be impressive if it could be established that the same sort of deposition occurred worldwide over the same period.  They seem to have ignored the distinct possibility that all this material came from some other part of the Earth.