Accretion

[Light Storm]

As the earth swings through it's orbit spinning much like a stick in a cotton candy machine it sweeps up meteorites and space dust. Estimates vary, but the USGS says at least 1,000 million grams, or roughly 1,000 tons of material enters the atmosphere every year and makes its way to Earths surface. One group of scientists claims microbes rain down from space aswell. Some proponents for a growing earth will do the math a tell you that over the course of two hundread and fifty million years, a thousand tons a year = a pretty freaking big number... but as big as the number is, it is defiantly insignificant in comparison to the mass of the earth.

[Light Storm]

• Meteoric and asteroid accretion. This is currently a popular theory, proposed also to explain some of the various extinction events that have plagued the Earth. It basically says expansion is caused by an accumulation of extraterrestrial debris over time. This theme was rejected by Carey as the primary cause of Earth expansion, since expansion should then decrease exponentially with time, not increase as shown by the oceanic mapping. Nor does it explain ocean floor spreading, or the distribution of oceanic crust or covering sediments.
  
  SOURCE: http://www.jamesmaxlow.com/main/index.p ... sition=7:4

[Dinox]

• Meteoric and asteroid accretion. This is currently a popular theory, proposed also to explain some of the various extinction events that have plagued the Earth. It basically says expansion is caused by an accumulation of extraterrestrial debris over time. This theme was rejected by Carey as the primary cause of Earth expansion, since expansion should then decrease exponentially with time, not increase as shown by the oceanic mapping. ...

It’s always surprised me that Professor Cary should use that particular argument to dismiss cosmic accretion of material from outer space since the idea that accretion has stopped comes from the concept of a constant diameter Earth. In the constant diameter Earth model, it is only natural to assume that cosmic material from outer space must have been much greater in the past. There must have been a vast amount of material from outer space at the beginning of the Earth’s formation and then it must have died away to a low rate. In contrast, in an expanding Earth model the amount of material available for accretion must have been more or less constant over the lifetime of the Earth.

In practice the concept that the Earth has been regularly bombarded over geological time by cosmic material from outer space is well developed. It’s been argued by various people that the Sun and planets travel around the galactic centre roughly every 200 million years (a galactic year). As it moves around the centre of the galaxy it bobs up and down so it passes through the central dust plain every 30 million years or so. On its journey, it must pass through many dense regions of space, so the rate of accretion would vary greatly over millions of years. Some regions of space are over a million times denser than the region we are presently traveling though. So a few million years ago, the rate of accretion could have been much greater than the present for example. Perhaps a few million years in the future, the rate of accretion could increase once again, but the average rate of accretion would be enough to continue to form the Earth over geological time.

[Florian]

In practice the concept that the Earth has been regularly bombarded over geological time by cosmic material from outer space is well developed. It’s been argued by various people that the Sun and planets travel around the galactic centre roughly every 200 million years (a galactic year). As it moves around the centre of the galaxy it bobs up and down so it passes through the central dust plain every 30 million years or so. On its journey, it must pass through many dense regions of space, so the rate of accretion would vary greatly over millions of years. Some regions of space are over a million times denser than the region we are presently traveling though. So a few million years ago, the rate of accretion could have been much greater than the present for example. Perhaps a few million years in the future, the rate of accretion could increase once again, but the average rate of accretion would be enough to continue to form the Earth over geological time.

Yes, but the putative accreting matter accumulates inside Earth not at the surface, or there would not be this huge transport of matter from inside toward the surface.
So if accretion is going on, it is not just "dust" or the regular matter we know, but more likely elementary particles that are not detectable at this time.
Another daunting question is "why are some bodies accreting stuff and are therefore tectonically active, while other are not accreting and thus not tectonically active (Mimas as an example)?". These questions cannot be answered as long as the nature of the hypothetical accreting matter is unknown.

[Dinox]

In practice the concept that the Earth has been regularly bombarded over geological time by cosmic material from outer space is well developed. It’s been argued by various people that the Sun and planets travel around the galactic centre roughly every 200 million years (a galactic year). As it moves around the centre of the galaxy it bobs up and down so it passes through the central dust plain every 30 million years or so. On its journey, it must pass through many dense regions of space, so the rate of accretion would vary greatly over millions of years. Some regions of space are over a million times denser than the region we are presently traveling though. So a few million years ago, the rate of accretion could have been much greater than the present for example. Perhaps a few million years in the future, the rate of accretion could increase once again, but the average rate of accretion would be enough to continue to form the Earth over geological time.

Yes, but the putative accreting matter accumulates inside Earth not at the surface, or there would not be this huge transport of matter from inside toward the surface.

I would agree. At first sight, there does seem to be a fundamental difference between the accumulation of cosmic material from outer space and the geological evidence for the expanding earth. Cosmic material accumulates around the outer layers of the earth, but the expansion of the earth seems to be caused by extrusion of new material forming at mid-oceanic ridges coming from the interior of the earth.

But there may be an explanation for this. Firstly, weathering and erosion effects would mean that cosmic dust wouldn’t stay long on the earth’s surface. Present day erosion would remove all surface features on the earth including mountains in a few million years. A loose layer of cosmic dust would be washed into the sea in a relatively short time.

I could imagine that this cosmic dust would become trapped in ocean trenches as it was swept around the sea floor by ocean currents. Once in the trench it would be subducted into the earth simply because cosmic material tends to be slightly denser. This isolated subduction of new cosmic material into the earth would continue for millions of years. The ocean trench would effectively form a conveyor belt of new cosmic material into the interior of the earth. Eventually the subduction of this new cosmic material into the interior of the earth would cause the earth to expand giving the impression that the expansion comes from the interior of the earth.

[Florian]

But there may be an explanation for this. Firstly, weathering and erosion effects would mean that cosmic dust wouldn’t stay long on the earth’s surface. Present day erosion would remove all surface features on the earth including mountains in a few million years. A loose layer of cosmic dust would be washed into the sea in a relatively short time.

Except that this layer has to exceed 20 km in one million year according to the current growth rate estimates. You can easily figure out that this hypothesis does not hold one second.

[Light Storm]

But there may be an explanation for this. Firstly, weathering and erosion effects would mean that cosmic dust wouldn’t stay long on the earth’s surface. Present day erosion would remove all surface features on the earth including mountains in a few million years. A loose layer of cosmic dust would be washed into the sea in a relatively short time.

Except that this layer has to exceed 20 km in one million year according to the current growth rate estimates. You can easily figure out that this hypothesis does not hold one second.

Best example I've seen for the incoming dust that effect surface level is the moon. The layer of lunar dust has accumulated since the planet originally cooled and it's not that think. When I think of possibilities of accretion being a viable mechanism for expanding earth, I look to to the words of Carey who said the explanation had to be found in the creation of matter in the universe.

You wouldn't think the worlds smallest living organisms would support and grow the mass of the planets largest ever in existence creatures but they do. Much in the same way, upon checking the life cycle of stars, it seems when they are young, they are surrounded by a massive field of reflective dust. ... Where does this dust come from? Is it just debris in space that the sun has attracted, or is it possible some kind of chain reaction of the stars birth has started creating matter in the field around it? Over time, massive planets begin to form sweeping up all that material, and as time goes on, dust to rocks, to astroids to planetary collisions. The oldest stars that are dying are surrounded by massive planets. Sometimes called hot Jupiter's as they are clearly to big to be a rocky giant... I sometimes wonder....

The answer may not be in the biggest rocks, or the tiny space dust particles... but possibly in the elementary particles that combine to form that space dust in the first place. It's very possible that some form of process out there is still creating them to this day.

[Florian]

You wouldn't think the worlds smallest living organisms would support and grow the mass of the planets largest ever in existence creatures but they do. Much in the same way, upon checking the life cycle of stars, it seems when they are young, they are surrounded by a massive field of reflective dust. ... Where does this dust come from? Is it just debris in space that the sun has attracted, or is it possible some kind of chain reaction of the stars birth has started creating matter in the field around it? Over time, massive planets begin to form sweeping up all that material, and as time goes on, dust to rocks, to astroids to planetary collisions. The oldest stars that are dying are surrounded by massive planets. Sometimes called hot Jupiter's as they are clearly to big to be a rocky giant... I sometimes wonder....

The answer may not be in the biggest rocks, or the tiny space dust particles... but possibly in the elementary particles that combine to form that space dust in the first place. It's very possible that some form of process out there is still creating them to this day.

That's a lot of speculation without supporting evidence.
The current working hypothesis is that cosmic dust comes from stars. You can certainly find literature on this subject.

[Dinox]

You wouldn't think the worlds smallest living organisms would support and grow the mass of the planets largest ever in existence creatures but they do. Much in the same way, upon checking the life cycle of stars, it seems when they are young, they are surrounded by a massive field of reflective dust. ... Where does this dust come from? Is it just debris in space that the sun has attracted, or is it possible some kind of chain reaction of the stars birth has started creating matter in the field around it? Over time, massive planets begin to form sweeping up all that material, and as time goes on, dust to rocks, to astroids to planetary collisions. The oldest stars that are dying are surrounded by massive planets. Sometimes called hot Jupiter's as they are clearly to big to be a rocky giant... I sometimes wonder....

The answer may not be in the biggest rocks, or the tiny space dust particles... but possibly in the elementary particles that combine to form that space dust in the first place. It's very possible that some form of process out there is still creating them to this day.

That's a lot of speculation without supporting evidence.
The current working hypothesis is that cosmic dust comes from stars. You can certainly find literature on this subject.

NASA has many amazing pictures of star formation regions like this one – the Pillars of Creation. Many stars (and presumably planets) are forming now. The relative velocity of some stars indicates that these few have passed through the cold cosmic dust so they only have low amounts of cosmic accretion at the present.

[Dinox]

Here’s an excellent video that I've just come across that illustrates the journey of the Sun and planets around the galaxy. As I've explained previously this journey would mean the Earth would regularly enter various dust clouds and this might be part of the mechanism for the mass increase of the Earth over geological time. (See previous planet formation region posts)