( Blog for website at http://users.indigo.net.au/don )
Fig.1. First order consideration. The smoking gun, .. is the length difference between the African coast, i.e., where the spreading ridge used to be, and where it is now, which is about times two, and which reflects the enlargement of the Earth since the ocean floors broke through.
Now, .. this is not where (my own) realisation of Earth expansion began, and very like doesn't occur to most regurgitators of Plate Tectonics, who probably never give it as much as a passing thought, but if I were to take a best shortcut along the path of empirical observation from years ago to the present time (and the theme of this blog), then the increasing length of the spreading ridges as the ocean floors grow would probably be it, .. because it can only mean one thing, .. that the ocean floors grow *UP*. (Shortcut that is, .. it's not the only cut.) In other words, the continents don't move away from the ridges - the ridges move away from the continents, which means 1. that there is no subduction, and 2. that the separation of the continents is an artifact of this upwards movement as the spreading ridges grow. Continuing upwards growth means that the surface of the Earth moves out from the centre, .. actively at the spreading ridges (by upwards growth) and by curvature correction for the rest of the Earth, which is continually gravitaitonally correcting its curvature to keep up with ridge growth. The continents are therefore to be seen as the surface expression of a smaller Earth, and lack the plethora of faults that make up the growth of the ocean floors. Correction is therefore most seismically destructive within the continents, particularly at the juncture with the newly developed ocean floors, which is the locus of most differential movement. The reason the ocean floors don't show the same seismicity as the continents is exactly the corollary of the reason why the continental crust does, .. namely that the ocean floors are riddled with the plethora of faults that facilitated the growth of the ocean floors, .. faults that the continental crust doesn't have. Just as a chain is only as strong as its weakest link, so we can regard faults as 'weak links', .. and a chain full of weak links has virtually no strength whatsoever. In-situ correction of the ocean floors is then little more than local subsidence. The seismicity would hardly noticed, and would be either recorded as insignificant - or not recordable. It is, more or less, seismically silent. The continental crust however, lacking this plethora of faults, is a comparatively deeply rooted, strong chain.
The difference in a dynamical sense between continents that move away from ridges, and ridges that move away from the continents (expressed as upwards movement at the ridges and curvature correction elsewhere) means that the 'rainbow' map of crustal ages does not truly represent the growth stages of the ocean floors, because it does not properly represent the along-ridge growth. Ridge insertion is taking place all at the same time, so that some sectors of the ridge are older than others. The simple linear congruence of 'coloured ages' with the spreading ridges is just that :- simple .. or, rather, simplistic. And simplistic to the extent of being misleading.
The devil of discrimination however, is in the detail. Average magnetic profiles reflecting field reversals are 'noisy', but in that noise resides the signal of along-ridge spreading that is being missed. These days, almost certainly there would be no encouragement to revisit the raw data to check this, since it is to the detriment of the ruling paradigm, and even if one could, the noise factor would anyway render it inconclusive. But it doesn't matter. The point is apparent at a glance (Fig.1). If the continents once fitted together, then no matter how plate 'movement' is conceived to accommodate spreading along the ridges, the ridges as they appear today have virtually doubled in length compared to where they used to be when the continents first parted. They haven't just moved away, .. they've doubled in length.
This face value evidence is supported by the total integrated picture of the ocean floors as a whole, .. transform faults as normal faults, .. their aggregate configuration relative to continental rupture, .. the difference in length of continental margins compared to the length of spreading ridges today, .. the stepped distal offsets of transform faults, (.. etc.) and of course everything that spells the failure of plate tectonics in the face of young ocean floors and the fallacy of a Panthalassa.
Plate Tectonics simply ignores this difference in lenth of the spreading ridges compared to the continental margins. Or more accurately, plate tectonicists simply ignore it. Why? Because to be part of the club you have to publish. If you don't publish you probably don't even have a job.
There's no mileage (and no future) in publishing controversial stuff. That's the bed that science of the consensus sort makes for itself, .. the pay-off that returns to science when it takes scientists on to the payroll. Consensus is a human affair, and not in the interest of science. Those who think it is, and that scientists ("The Team") are doing a great job, should take this into account.
[ See also - Debunking Plate Tectonics - at :-
http://www.platetectonicsbiglie.blogspot.com/ ]
So you're saying that "the 'rainbow' map of crustal ages does not truly represent the growth stages of the ocean floors, because it does not properly represent the along-ridge growth." How would that map look like if it did? What's wrong with the rainbow map? Is it just too coarse-grained? What changes would have to be made to the map in order for it to reflect your views more accurately?
ReplyDeleteI haven't explored this as much as I would like, .. but I think it would look a lot more patchy along the ridge than it does (and particularly on the older sectors of the ocean floors), to reflect that the ridge does not grow everywhere at the same rate, or even at the same time, but rather segments of it grow more than others at different times. The classic profiles of striping on opposite sides of the ridge look good when they're marked up with big black stripes, but the drawn profiles from line to line, are a lot less clear.
ReplyDeleteSuperficially the earthquakes today are the full extent of the ridges, which makes it look like the ridge is developing all at the same time, but in detail they are not. Earthquakes are more on the transforms than on the ridges, and on some transforms more than others, and there are fairly large sectors of ridges that are relatively silent (e.g. the Southern Ocean). Ridge growth is relatively silent. Most of the noise is transform growth, and the 'tonal' pattern of the ocean floors at the ridges varies quite a lot. (Compare the Southern Ocean with the Indian Ocean.)
Also, certain lines of displacement seem to be more active than others too. In the Indian Ocean for example, there's about 3,000km of ridge growth in the mantle that represents a knife-edge separation of Australia from India in the continental crust, on a line that goes right up through China (parallel to the Owen Fracture Zone) (= the killer earthquake zone).
Even superficially, geo-*logically* the Atlantic is substantially later than the Pacific; it only began to open once the Americas were fully scissored open (and then proceeded to override fully half of the Pacific). Both ridges are active at the present day (earthquakes), but the early history (colours) doesn't have the same symmetry (American scissoring again). The blanket green colour doesn't do much justice to structural sequence. I reckon much crustal separation is due to crust-mantle detachment (= 'flat') rather than simple pull-apart ('vertical') - which is not easily represented in colours that depict symmetry across the ridge. (And how they talk about that symmetry in one breath, and "independent plate movement" in another, is just beyond me. Symmetrical striping and "independence", are bald contradictions. How do they get away with it in the classroom I don't know. Teacher has the Power of the Book, .. and the backing of a lot of 'clever people' who are looking for plate tectonics on Mars..)