.....Plate boundaries - 'moving' plates
           (...Plates and plate boundaries, ..the knot that Plate Tectonics has tied itself in... )

Fig.1.  The conundrum of 'plates'.  Plates move, but their boundaries don't?  Just as water passes beneath the window of a glass-bottomed boat, so the oceanic lithosphere is supposed to move beneath the boundaries of lines depicting plate boundaries on plate maps. (Blue = oceanic lithosphere which moves according to the arrows; red = 'window'/ plate boundaries on plate maps which are fixed; arrows = pull of subducting lithospheric slab.)

 

Plate maps are misleading because they don't really show *plate* boundaries at all  ..at least not in the sense meant by Plate Tectonics, .. of segments of the Earth's crust ("jigsaw pieces") that move independently about on the Earth's surface.  What they do show is something more like the plan of a collection of escalators. When switched on the moving part that conveys us from one level to another, or from one part of an airport to another is certainly moving, but the escalators themselves are not.  The 'plate' boundaries are equivalent to the body of the escalator as a whole.  In other words, the boundaries of the plates (escalators) are fixed, but its internal parts are moving

Or like the revolving wheels of a bicycle that is jacked up so there is no traction with the ground. The wheels go round, but the wheel moves nowhere.  Or a revolving drum that has somehow worn its way up through a floor; the drum (plate) moves from one side of the eroded slice in the floor to the other, but the margins of erosion (the plate boundaries) are fixed.

In other words, the plate (which is the exposed frozen surface of a convecting cell) moves nowhere; there is movement within the plates, but the plates as a whole are not moving - much like water moves beneath the window of a glass bottomed boat - the window defines the perimeter of movement, but that perimeter does not move. So it is quite misleading to talk about plates "pulling apart", "colliding", and "grinding past" each other.

Importantly too (another way of looking at it), the 'plate boundaries' do not belong to the plate (the part which is moving) but to whatever is defining the limits of movement.  In the drum analogy the boundary belongs to the eroded floor, in the water analogy it belongs to the boat.  On the Earth the plate boundary belongs to the continent or to the position of the spreading ridge, not to the moving plate.

So while it may be legitimate to depict plates on plate maps the way they are, as the exposed top part of the mantle (with or without a continent on top) it is highly obfuscatory to talk about plates moving (independently) about and "past each other" and "colliding", as if they are entities that actually move "independently".  They don't, any more that someone sitting in a chair reading a book might be said to be 'moving' on account of their blood circulation or digestion.

.................

Virtually by Plate Tectonics' own definition the paired boundaries of spreading ridges and subduction zones cannot move; for if  they did then they would have to move in the same direction and at exactly the same rate for the Earth's surface to maintain a constant size.  The only way Plate Tectonics can maintain its position of plate movement is to say that plates came into existence already formed at their present size and location - which is also a nonsense.

The reason for this peculiar state of affairs is a clash between traditional geology which discriminates between crust and mantle on compositional and general geological grounds,  and the more modern field of geophysics which does not, but discriminates simply the outer brittle shell of the Earth (be it crust or mantle) according to the distribution of earthquakes, and which has coined the term 'lithosphere' to define this combination of brittle (on account of earthquakes) crust and upper mantle.

Earthquakes occur in two markedly distinct zones - the spreading ridge and the subduction zone.  At the spreading ridges earthquakes (i.e., by definition lithosphere, ..i.e., crust + upper mantle) reach to a depth of some 6-12km.  At the subduction zone earthquakes reach to a depth of some two orders order of magniture greater, 600-800km, ...on occasion up to 1000km, i.e.,  well past the depth regarded as upper mantle.  Here, 'crust' is rather a misnomer, because these earthquakes occur not in the crust (as geo-logically defined), but at the interface between continental ltihosphere and oceanic lithosphere, reaching below the upper mantle and well below the 20-40km superficial thickness usually designated 'crust'.

Spreading centres and subduction zones are zones of brittle deformation which describe correlative movement, i.e., movement at one side (the ridge) is matched with movement at the other (the subduction zone) even though the sides themselves (the 'plate margins' described above) do not move, yet the part in between which is the 'plate' proper and which is supposed to move has absolutely no seismic activity at all.  Seismically it's as seismically dead as a dodo!

So the plate margins which don't move are seismically active, but the main body of the plate itself - the vast expanse of ocean floor - which does move (is supposed to move) is seismically dead?   How is that?  Plate Tectonics matches the earthquakes of the spreading ridge with those of the subduction zone on grounds of plate 'movement', and yet the great expanse of ocean floor in between which is supposed to move is seismically dead?

The only way this seismic silence of the ocean floors can be explained is in fact if they are just that - silent; dead as a dodo!  In other words,  the plate is not moving away from the ridges at all, but the ridges are moving (or rather 'growing') away from the continental margins leaving a 'dead zone', a zone of inert, fossilized ocean floor in their wake.

But the ridges manifestly do not move on the Earth's surface.  Equal spreading on either side of the ridge precludes it.  So we are left with the inescapable conclusion that the only way the ridges can 'move' (but not move east west north or south), is if they 'move' UPWARDS, so necessitating areal movement as a corollary.  That is, movement in two dimensions is apparent only, consequent on real movement, which is in the third dimension, ..upwards, ..outwards from the Earth's centre; ...i.e.,  the continents are fixed, and only appear to move apart as the ridge moves upwards.  Well, ..of course they move apart relative to each other, ..but not to their basement: they are fixed to their basement.  Which is why the crust-mantle boundary beneath the continents is so difficult to recognise, and why the continents are said to have "deep roots"

(Googlesearch <continents "deep roots"> = results of about 11,100 for <continents "deep roots"> ).

Thus the  200km mantle thickness of of strong seismic activity at subduction zones is logically not at all paired with the seismicity at spreading ridges in the way meant by Plate Tectonics, ..these two seismic zones actually represent different things (as described on this site) - nothing to do with "moving lithosphere".   (And just briefly what are they?  Well, the ridge represents mantle growth; the so-called subduction zone represents accommodation of the pangaean hemispheres.  That's it, in a nutshell.)   Remember too the point above, ..that the plate margins do not belong to the plate, but to their contiguous neighbour.

So, ..having defined plates as  'lithosphere' (upper mantle + crust), and recognising that lithosphere is 200+km thick at subduction zones and extends down to around 800 - 1000km,  Plate Tectonics is in the position of having to represent the boundaries of plates (lithosphere) (i.e., the plates we see on a map) using only the visible crust.  It attempts to do this by distinguishing 'plate' (the flat part of the ocean floors) from 'slab' (the going down part) (Figure above), and scribing the line on the bend between them, but it is really in a no-win position. Scribing lines on the surface of the crust does not define 'plates' as Plate Tectonics needs them to be  Segments of crust appearing to move whilst plates do not is hardly justification for talking about "moving plates" - i.e., lithospheric margins that are fixed whilst the lithosphere moves through them -  ...and not even through them, but beneath them.  It is Plate Tectonics own definitions which have led to this conundrum, and which has led the Geological Society of London to deplore on the way this has carried through to the erroneous teaching of Plate Tectonics. However it is merely pointing out a deficiency in logic, not offering any solution to the conundrum.

The short of it is that Plate Tectonics is exactly that -  a depiction of two-dimensional global geology, whilst in reality, (and implicit in Plate Tectonics' own definitions) the major features of the Earth's crust are manifestly a result of dynamics in the third dimension - outwards movment from the centre.   Up and down.  Which is what the crust of an expanding Earth does: moves up here and moves down there as the crust accommodates the enlarging surface of the Earth.  Plate Tectonics on the other hand negates this up and down movement, relegating it to second place in importance of the created dynamics as the 'plates' (implictly with boundaries and all) "move, slide, collide and grind past each other" - in two dimensions.

(Plate Tectonics  = Flat Earth Society reborn.)
 
 

Got a question?
Ask a Guru.

| frontpage | nonsense | expansion |

http://www.crichton-official.com/speech-alienscauseglobalwarming.html