@farmerman,
farmerman wrote:
Quote: At the crust, there are obviously all the complexities of subduction and plates floating on top of the subducting material, but I assume that as you go deeper, the rising temperatures and pressures soften things up to where they can consolidate/compress as they fall deeper and deeper. Do you think there are reasons they wouldn't, such as the way the plates at the surface remain solid and resist collapsing into the subduction zone together with the subducting plate?
Not a bad beginning understanding actually. Why did you start off with all that crap where you denied how plates actually move?? My model of crust and shallow mantle plates being "carried " along like pizzas in a "tunnel oven" that employs a chain drive "conveyor belt" is pretty much the lab of a plte junction xcept theres not much subducting to the center of the erth. Its a fairly shallow mchanism (20 to 70 miles not 700)
I was never in conflict with anything you said or anything that I've studied about plate tectonics, except the assumptions about where the energy comes from and how it works. You were the one who got worked up about me questioning and contemplating alternative models about how it works and how the energy moves.
I still stand by what I said about the relationship between kinetic and potential energy. There was never a reason to attack me for that. Your 'pizza slices on a conveyor belt' illustrates that the powered motion is occurring underneath the crustal plates and that they are sort of floating on top of it, but I think it's also important to think about the shedding of coastline into the ocean over time, which would dump bio-energetic sediments from the land into the ocean where it would get subducted. E.g. you have forests growing on the side of the mountains, which catch the clouds and deliver the water into the valley, which is fertile as a result. Over time, that stored energy must build up in the ocean and get dragged down via subduction. So the crust is not just floating on top of the mantle-conveyor, but it is also sedimenting over time and then breaking off at the edges to feed the energy it has caught and absorbed down into the mantle.
Quote:The only thing that you need to understand is that the conveyor belt (convection cells) CARRY these tectonic plates by using inherent heat, density differences and zones of convection that make the surficial, less dense. crustal plates get carried along like theyre riding on trays. (These plates, have hardly any tensile strength or pressure rigidity) They are made of material that stratifies as it rises at the mid ocean ridges(lighter Sialic -[silica/aluminum] rocks like granite rise and form the crustal surfaces ] and these overlie( by density separation), the more dense layers of Simatic rock [Silica-magnesian rocks} and underneath all of these are the most dense magma cells of the upper mantle composed of ultra Mafic [magnesian-felsic (very little pure quartz silicates)) These are the green olivines, peridotites etc. Thee are like the dense blobs in a lava lamp and since the earth is an oblate sphere , the lava lamp blob can rise travel along a bit and then ink back into the deeper mantle as it cools and the KINETIC energy is converted from EXISTING heat to physical motion and then density(gravity) separation
Ok, thank you for beginning to talk in terms of convection powered by energy. I just happen to suspect that when the lighter material cools and sinks, it has also absorbed chemical energy from biosediments, which means the convection process that brings up hot material also makes room for heavier material to flow back down and bring with it energy captured at the surface.
Quote:Its a bloody pizza with a light cheese on top and denser tomato sauce underlain by a dense crust. The hot conveyor belt runs through the hot oven at a fairly constant pace.(So it is with the mechanics of plate convection).The only difference is that a pizza oven is driven by a motorized conveyor and continental drift is driven by the THERMODYNAMICS of crystallization (where density separation of minerals , like quartz rich silicates lie on top of rock which crystallizes out roughly at densities of of 2.64 to 2.67 and the MAFIC rock have a density of about 2.7+ to 3 and ULTRAMAFICS lay at the bottom like 3to 3.something )
What do you mean when you say "the thermodynamics of crystallization?"
My understanding of the spreading ridges is that hot convection currents are rising up through the mantle and then forming strips at the spreading ridge whose magnetic polarity changes every so often because the Earth's magnetic field alignment flips.
I see the spreading ridge as a growing undersea mountain range, which erodes and thus gradually pushes material toward the subduction zone. In a sense, the subduction zone is like a river running through a valley that carries sediments further down to the ocean, only I don't know what the 'ocean' of the subducting mantle is, besides the mantle itself. You say the subducting material only makes it down 20 to 70 miles, but then where is the convection current that pushes up material at the spreading ridge originating (i.e. at what depth?)? If material is rising from some depth and other material is falling down, then I would expect there to be something like a vacuum process where the falling material must flow toward the low pressure being left behind by the rising material.
Quote:So the big The difference is that the pizza HAS rigidity and can be slid around with a peel whereas a model of the erth crust (would it be a table sized planet , would have the earth composed of various kinds of whipped cream an moussees. We have no mechanical physics that allows us to really pull a slab of whip cream around with a rope nor could you push it so that it would stay together.(try pushing a carpet)
When you are cooking a soup, a crust can form from materials that are in the froth floating on the top. If the soup is simmering and not at a rolling boil, that froth island will more or less retain a certain shape and position, but it can float around a bit and change shape as the denser liquid soup flows around under it. I'm sure that's not a perfect analogy but I think it is a good example of an island floating on liquid that doesn't have real solidity or tensile strength as a solid thing, which nevertheless appears solid in comparison with the liquid underneath it.
Quote:
You made it ckear that you think I was only "poing words" an
What I said was that things you wrote before didn't contain explanation in addition to the slew of esoteric details, so it was not immediately clear whether you had some mechanical understanding of what you were talking about or whether you were just posting about bunch of details like pieces of a puzzle without really understanding how they fit together and thus being able to explain them.
Quote:1 you thought my nalogy of poizza was demeaning and
Idk about 'demeaning,' but I didn't think that analogy contains any insight into the relationship between kinetic and potential energy. It is more an explanation of how the crustal plates are being pushed rather than moving by their momentum. I now understand why you were saying that, but I am still thinking critically about where the moving conveyor (mantle) is getting the energy to push those plates into each other and thus build mountains.
I know the mainstream theory is that all the energy comes from primordial heat and nuclear decay and that fossil(ized) energy/fuels don't contribute much if anything to the interior heat and tectonic power, but if you look at how deep they are fracking and digging to get to the tar sands, etc. then it seems clear that a lot of material has piled up on top of those ancient layers since the time they formed from biological sediments at the surface.
As those layers get buried ever deeper and other material is moving up to the spreading ridges at a convection current, there must be something like a low-pressure zone that allows mantle material to keep descending along with all the fossilized energy sediments it contains. In that case it is like a hopper where if you put an inch deep layer of fuel at the top of the hopper, by the time it sinks halfway down the hopper, it's going to be pushed together and thus doubled in thickness. In other words, the triangular/cone shape of the hopper compresses the material as it sinks down, so if that is happening to energy-rich material as it sinks down through the mantle, that could explain why the temperature gets hotter as you go deeper/closer to the core.
Quote:Analogy , Ive found, is on of the best ways to get students to "get it". It only requires one thing of the student. Admit that he doesnt know anything about the subject and just listen.
THEN, there are always follow up papers and literature that develops all these theories and evidences them quite well.
I think, to the contrary, that if you want people to pay attention and understand something, you have to make them realize that they already understand something about the subject they're learning about. That's how analogy works. If someone can already grasp how a pizza slice would move along a conveyor belt, then you can use that analogy as a basis for explaining to them how plate tectonics works.
Quote:BTW We have many ways to verify all this but since you seem to just want to carry on an argumente from ignorance, we probably wouldnt ever exchange any ideas where you can learn something despite yourself.
Yes, I would much prefer to discuss the methodology and theoretical models it is based on than to fight, as you often seem to prefer.
Quote:On rereading the very posts where you and I left the road I noticed that you actually started getting snotty with me when I talked about the pizza "model" before. Maybe you were thinking I was being snotty myself. I WASNT. we use that analogy all the time because geology and geophysics actually allows it.
I don't remember, maybe. You poke and pick fights so I fight back. I don't like it, but I'm not going to let someone accuse me of being an idiot who doesn't understand anything I'm talking about; not because I'm trying to defend my own ego but because I'm trying to maintain an interesting and relevant scientific discussion based on real legitimate scientific concepts and if people just accuse me of completely misunderstanding all the science, then it undermines my whole interest in having fruitful scientific discussions online.
Quote:THE WORLD IS OUR LAB and I can take a student or a whole bunch of em (We call these field trips) out to the lab and we can see this stuff ON THE HOOF. I can take you to any spot where the plates from the Grenville Period , form the edges of an entire country we call CAnada. I can show you the locations where we can actually TIME the events and movements of the Plates in the Snake River Plain or the Pine Moutain Thrust sheet in the Appalachians. We can see subduction and descending plates and mountain building along the flanks of Chimborazo or along the entire ridge of Sumatra/Java. If youd simply asked something like "How do you know this is so"? one item at a time, maybe I wouldnt have been so brusque and dismissive of you.
My wife brought it to my attention that"its the damned internet, you dont have to write his advisory evaluation "
Glad to hear your wife is a peace-maker. With the internet as bad as it is, just imagine what would it would be like without such peace-makers behind the scenes!
You are right that it is better to discuss things 'one item at a time' systematically instead of just yelling back and forth without clarifying things being shouted. Shouting matches are idiotic and a waste of time, even when the information being shouted is relevant to some meaningful context.
It sounds very interesting to travel and see all these kinds of things you are talking about that make the world a geological laboratory. As I've aged, I've found that there are documentary makers and photographers who get such good footage it can be better to watch it on a screen than seeing it for myself. I do like seeing mountains in person just to get a feeling for the immense scale of how much material there is and all the potential energy of elevation contained in them. I've never seen an avalanche/rock-slide/mudslide in person, but I always think of them as the example par excellence that demonstrates conversion of potential energy (of elevation/altitude) to kinetic energy (of motion and then friction/heat).
Still, and I think you hate to hear this, I still like to compare the energy it takes to push up mountains with the energy it would take to build the same mountain using bulldozers and dumptrucks, ovens to bake the rocks, etc. There is a huge amount of energy that goes into building a mountain range, and I think people fail to appreciate that all mountains are gradually being weathered and eroded into the valleys, oceans, and ultimately subduction zones.
If we leach out all the energy at the surface layers before the material can make it down deep into the mantle where it will help power the convection furnace there, the mantle will cool and mountain-forming and plate tectonics will eventually slow and/or grind to a halt. This may take hundreds of thousands of years, but we should realize that the Earth has been working for millions and billions of years in the past to amass the energy currently contained within it. I know you insist that the energy was mostly just there as primordial energy when the planet formed to begin with, and/or that the nuclear fuels within it are contributing most of the energy, but I just have a hard time believing that the sun isn't communicating fusion energy into the interior via surface processes that form, sediment, and subduct fossil(ized) energy/fuels.
It is just logical that life on Earth evolved as a chemical interface for connecting the sun as a power source with the interior of the planet. It would not make sense for life to evolve at the surface as nothing more than something superficial that doesn't connect with the longer term functioning of the planet as a whole mechanical energy system.
