I agree, facts are subject to change, even the ones we are sure are correct. I could think of several reasons why Europa would have its own version of plate tectonics. While his graphics were nice they really didn't prove anything. Yes, that's all I was doing. I haven't heard the theory about Olympus Mons causing the Valis Marineris, sounds better than the water erosion theory which I don't like. We have a long way to go before we understand Mars geology. I am no expert on plate Tectonics but I honestly did not realize the Ocean floor is as young as it is. Even allowing for the volcanoes some of the Ocean floor should be much older, at least I would think so. I will have to look more into this. The new theories always face entrenched interests and push back from orthodox scientists, which are the vast majority. So I do like to give the fringe guys a look, most are wrong but at least it's something new and different and occasionally they are right and change our understanding of the world and the Universe. These are also the ones we remember. CO2 in the Ocean - we won't go there today. Thanks for your detailed responses. Bob -----Original Message----- From: utah-astronomy-bounces+robtaylorslc=gmail.com@mailman.xmission.com [mailto:utah-astronomy-bounces+robtaylorslc=gmail.com@mailman.xmission.com] On Behalf Of David Rankin Sent: Friday, January 14, 2011 7:20 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] Expanding Earth? Robert, I figured you were trying to stoke an interesting conversation. I like a good challenge to what I see as current understanding. I know our "facts" are always subject to change :) Plate Tectonics actually does exist on Europa, but it's mantle is liquid water, and its plates are ice. I think I remember my astro 101 teacher saying something about the Valis Marineris. He mentioned a theory about Olympus Mons causing uneven stress on the crust and "ripping" apart the valis Marineris. I don't know if I buy that or not. One of my friends pointed out it looks like a "grazing impact" from a meteor, and I think I found a site where someone theorized about an asteroid like moon in retrograde orbit smashing into mars at a low angle. Its been shot down by anyone I've brought it up to. I remember learning that Mars didn't have the mass to retain its internal heat like the earth has. Maybe this lack of mass and heat never really got enough convection going int he mantle of mars to cause a crust thin enough to break up and move around? On the flip side, if the earth expanded, and mars is so similar, why wouldn't we see the exact same evidence he is claiming exists here, on mars? I agree that a lot of breakthroughs come from the fringes, at some point, big steps are made though. I really think the expanding earth theory doesn't explain much of what is observed. The guy states that the lithosphere is riding around on the oceanic crust. This is not true. At some point the oceanic crust gets thrust down deep into the mantle and is totally recycled. The Atlantic and pacific ocean basins are not "meeting up" under the Americas. Some part of the lithosphere sits on or very near the mantle. The ocean floors are made up of young rock because the rock is being generated at the mid ocean ridges. It spreads on the order of cm a year. It wouldn't then last for billions of years between continents before being recycled back into the mantle at an active margin. There are also differential rates observed in different ocean basins. This is all probably a byproduct of a dynamic mantle. An interesting note. The mid ocean ridges are huge mountains. As the fresh magma rises and goes through a process of adiabatic decompression, it starts out very buoyant and not as dense as it gets as it cools off. This is why the ranges are there, and as you move from them, they taper off. This process is only a function of the temperature though, so if the rates the ridge is making new crust increase, the mid ocean ridge ranges get wider. This displaces more water, and also increases volcanic activity at the active plate margins. The effect is higher ocean levels and more CO2 in the atmosphere. Sounds a lot like what the late cretaceous was like. David