At http://expansion.geologist-1011.net/ … the expanding earth theory is discussed from the perspective of a mainstream geologist. He begins by noting the expanding earth theory relies heavily on the assumption that subduction does not occur. What he should also have acknowledged is that Plate Tectonics relies heavily on the assumption that subduction occurs – and is not a figment of modelling. This is a different way of making the same point.
He continues by saying that subduction has been verified by isotope studies and even by GPS measurement. Ther latter points is presumably to do with the fact GPS does not show up the Earth expanding in the short term. GPS measurements do not rule out episodic expansion events.
He goes on to put it all in realistic perspective as he describes Plate Tectonics as a 'model' – and that is what it is, a modelled theory. He then says Plate Tectonics evolved out of Continental Drift theory and provides a mechanism for it to happen. The same could be said of the Expanding Earth theory, a logical projection from Continental Drift. Unfortunately, as noted by the author, the expanding earth theory lacks a suitable driver – in his opinion (and that of mainstream in general). Malaga Bay did provide a means to account for expansion, a release of gases from the upper mantle, but the driver would have been external I imagine – such as the asteroid that struck the Earth at the K/T boundary. See the following posts to get an idea of what Tin Cullen was saying a year ago – http://malagabay.wordpress.com/2013/07/13/the-inflating-earth-sea-level/ … http://malagabay.wordpress.com/2013/06/14/the-inflating-earth-equatorial… … http://malagabay.wordpress.com/2013/06/13/the-inflating-earth-antarctica/ … http://malagabay.wordpress.com/2013/06/03/the-fairy-ring-of-fire/ … http://malagabay.wordpress.com/2013/06/16/the-inflating-earth-4-gravity/ and most especially the first one in the line at http://malagabay.wordpress.com/2013/05/28/the-inflating-earth/ … and after that one might like to look at http://malagabay.wordpress.com/2013/04/11/terrestrial-degassing-of-hydro…
The author may not be up to date as most of his sources belong to the late 20th century. Another problem is there are a host of different versions of the expanding earth hypothesis – mainly because people have arrived at the idea from different directions. Most of these ideas will probably fall by wayside. The author provides some examples of such ideas. For example those of Carey (1988) and a mass accretion process associated with an expansion of the universe.
Another point he makes concerns the paucity of subduction zones in relation to the mid ocean ridges and fault lines, which are twice or three times as many. He makes the simple observation that length is not the same as intensity of displacement at the subduction zones. He is getting round the problem by saying transform faults and mid ocean ridges can be as long as you like if subduction occurs at a few places but at a rapid and intense level. On the face of it this line of rationale has some credit until you start thinking about what he is saying. If the ocean floor is spreading in one direction it must be subducting to counter-act that addition to the sea bed. The Atlantic is supposed to be being pulled apart at the seams – along the mid ocean ridge. Where is the subduction taking place – in the Pacific? If so why would that involve a small area of subduction, no matter how fast the plate was moving?
However, he also claims subduction processes have been confirmed by cosmogenic isotopes such as Beryllium 10 (10Be) that are produced exclusively by the interaction of cosmic radiation with atoms in the earth's atmosphere and on the Earth's surface. With just a half life of 1.5 million years the presence of 10Be in lava erupted in continental and island arc settings is only possible if it is carried down beneath the eruption site by subduction and subsequently regurgitated. Sounds fool proof – is it?
In conclusion he is a lot more pragmatic. He says the most tenable expansionist theory is that of Owen (1983). He did not deny subduction but incorporated it into his model. He suggests an admixture of expansionist ideas with those of Plate Tectonics may enrich the latter, making for a more robust theory. He even goes so far as to compare this compromise with what has occurred in evolutionary studies, an admixture of gradual evolution with bursts of speciation which led to the idea of punctuated equilibrium. He says Owen's theory is elegant but lacks evidence of a driver – and ends up by saying Plate Tectonics is the best planetary tectonic theory currently available to science. In other words, the expanding earth people have to come up with some more evidence in support of their theory.