Tuesday, March 14, 2017

Erosion

non-slabG-McD2.htmlJust erosion - all by itself (Proof that the Earth is expanding). 


Rubbing the Earth away makes it bigger.
(Yes?  .. How?.)

Newton's Third Law :- "To every action there is an equal and opposite reaction".  [And check out about the (?)bad behaviour while we're noticing.]
 


 Aphorism or platitude, I'm not sure which, nor which way round the dominoes of action and reaction are when translated into cause and effect , but checking out the possibilities I find that keep rubbing the Earth away by erosion is very closely tied to it keep getting bigger, and that it's very strange that this quirky behaviour is not taken up by Plate Tectonics since it's pretty good at noticing silly things :-
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[Mountain building .. Just recapping something we mentioned earlier -  that except for volcanoes there is no such thing.  Volcanoes are the only mountains that get 'built' - and even those 'build' on the continual collapse of their lava and ashy aprons, as gravity pulls these down too.  All the others (especially the Himalayas since it is such a spectacular example of egg-on-face) are what's left after corrosion and erosion have their wicked way, .. leaving the question, well, .. how did the land get up there in the first place to be eroded?  Didn't it get, .. you know, pushed up, so that it could be eroded, .. like we learned in school, by plates moving at the speed your fingernails grow?  This is the question to keep mullers mulling when reading below.  (And also the implication therefore (for future reference), that there is no such thing as 'orogeny' as the term is generally understood.)

Just thought we should state that at the outset so that the position about erosion (below) is clear.)

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"Is the crust being pushed up ? Or falling down?"
"It's falling down.  You know, .. erosion, .. islands sinking /sea-level rising, .. the mantle as subducting slabs  collapsing into the deeps because they're cold and have the weight of the continents pushing them down in subduction zones where the continents are behemoths, ..bulwarks, .. fixed bastions of resistance against oceanic crust coming at them full-tilt from half a world away at the phenomenal speed your fingernails grow so the bastions of continents get to push them down the gurgler - by the slabful.  But at the same time they're getting crumpled up into mountains by the soft sediments piling up on them.  It's like football, .. Aussie Rules, you know, not the pussyfooting around sort of football like you get in Pommyland, but the game where Big Biffy Blokes grab you and throw you to the ground, just for trying to score a goal.  And kick you in the groin in case you try it again." 
"Yeah?"
"Yeah. Asparagus and spinach.  An' brocolli.  'Sgood for you. ladies'll love you an dentists will despair."
______________

Meanwhile, out there, .. on the Big Shippo HMS B.S. P.T. they're at it again. Only this time there's a new cook in the kitchen, and the story is a little different:-
[Narrator] :-  " It was a dark and stormy night.  The wind howled, the lightning flashed, the thunder roared and the storm blew, and the rain came down in torrents.  And the captain said to the cook, "Cook, .. spin us a yarn", and the cook began as follows :-
"Y'know, .. it's an odd fact, but wherever we go in the world the Earth's surface is being reduced to flatness.  Ice /snow, wind /rain, glaciers and rivers, and the relentless crash of waves upon the shore such as send sailors to their doom..  they're all working to make the Earth flat as a tack."
[Sailor 1.]  "Aw, .. C'mon Kook, .. not that one again .. "
"What?"
"About 'flat'.  Everybody knows the Earth's not flat."
"Ah never said it was."
"Yes you did."
"No I didn't."
"Yes you did.  You said the Earth was flat and the other lot were working, which is more than what you do most of the time."
"I said they were working to *make* it flat.  That means it's not already flat. Anyway here's one for you.  You know how Bad Bart fell off the crow's nest the other day and got wet because of gravity, and you know how gravity is serious about making it so you never get to sail over the horizon?  Well this is another brick from the wall of gravity."
[Sailor2.] "Belay pin in a fife rail, cook.  How long have you been on this ship, matey?
"Four weeks out from port ever since the King's Shilling, and nivver a regret either me 'earties.  You're as fine a bunch 'o lads as ivver I clapped on. 'Strewth."
"Yeah, .. well, don't go talking about brick walls, gravity, stones of any sort, or sending sailors to their doom on sea shores  Not on this ship."
[Sailor1] "That's wimmin, .."
"What is?"
"Luck. Women.  Doom, ..  an' thar be dragons, .. bad luck on ships they be."
"Who's talking about women?  I'm not."
"Well we wish you were, ..   .. "
"If it's bad luck and doom you're looking for just wait till dinner. Women?  They're all on that beach."
"Where?  Where? .. Where?"
"I think he means the one over the horizon .. "
..................

And so on.

So you can see how the dialogue is shaping up.  The crew are not interested in being sent to their doom upon the sea shore or anywhere else, .. and are not very enamoured either of the cook's story generally even though he's about to tell them a very serious thing about gravity, which before the crew got off the point and excited about dragons ... was, ... 



Simple Simon ...

Fig.1. Fractures in the rock, helping to reduce mountains to rubble.  And reduce it to underwater 'further-flatness'. [The mountain behind shows the bedding which is still nearly as flat as it was when it was laid down.]  Gravity1 =>scree-slope gravity2 => reducing it to underwater 'flatness' 1 (once more) => 3.

Yes, I know.  Under the water it's still pretty much like 2. but you know what I mean, .. eventually it gets to flatten off.  It's the finer fractions that get ground down and carried in suspension to the sea, and deposited there to be really flat - which in pre-oceanic times was probably not that far away, .. in fact the canoe in the bottom right of the picture might easily have been sailing on it (if it was a bit further to the left and out of the picture).

... Met a pie-man ...

< This image needs permissions to include; meanwhile see it here >
Fig.2  Gravity1 meets Gravity2 meets Gravity3 (again).  Cascading folds once formed at a deeper crustal level give way to cascading rubble at a high crustal  level.  Has land risen, or has the sea fallen?  Given that the frame of reference for an answer is sea-level itself the question is something of an oxymoron if not entirely inadmissable.  More observation is needed.  ("More research".) (Attribution Olafur Ingolfsson)

.. who would dredge up anything from a barrel of tripe and have you eat it, .. and have you believe in "mountains tossed high by the collision of plates" while you do.
Gravity and the relentless imperative of flatness.
( Earth being flat /round ) :- "What actually happens is that once scientists get hold of a good concept they gradually refine and extend it with greater and greater subtlety as their instruments of measurement improve. Theories are not so much wrong as incomplete. This can be pointed out in many cases other than just the shape of the earth. Even when a new theory seems to represent a revolution it usually arises out of small refinements. If something more than a small refinement were needed, then the old theory would never have endured."  (~ Azimov )
I don't think it's like that at all.  That's the way it finally gets written up once there is some water under the bridge and everybody gets a chance to clean all the egg off their face, when all the wrong stuff - like 'land-bridges' and sundering continents, and plates and convection and hills building up into mountains - get written out of the picture.

But Plate Tectonics has, remarkably, endured.  For more than half a century.  And not because it is right, or even partially right - not even the part about the creation of the ocean floors in the first place (which is the part about making the Earth bigger) is right - but because it is useful to whom it may once have concerned, and to those whom it still does.  It's been leading the public (and at least two generations of children) (growing into adults?) up the garden path to exactly the same cognitive deficit as those peddling organised religion by the management class have done.  That "small refinement" is exactly what happened in the transition from continental drift to Plate Tectonics, when what's needed is to go right back to the root of the problem and root_it_oot!  (And start over). Like here.  Plate Tectonics will eventually be written out of the picture, .. noted as a footnote, a passing curiosity in geology but a monumental example of how science works - or rather doesn't.

 All those "outsiders with no need of structural geology") developing the change to Plate Tectonics did was to partition the mantle into an upper part and a lower part and postulate a shift in the important dynamical interface from between the crust and the upper mantle (as in continental drift) to that between the upper mantle and the lower mantle (as in P.T.), as "greater subtlety" was able to be measured.  In so doing they not only rejected the continental retrofits on a 1/3rd - 2/3rds Earth (evidence that the Earth must once have been smaller by the extents of the ocean floors), they also rejected the straightforward implication of their own research - the fact that the mantle outcropping between the continents was everywhere young, which meant that the earlier surface area of the Earth had increased by that amount.

Why did they do this?  Well, there were a number of reasons but principally they were flags of convenience, hoisted in order to quarantine the 'disease' that had already appeared on the horizon in the form of HMS S.W. Carey, who was rejecting continental drift (by convection) and postulating instead that the Earth was getting bigger, .. which was threatening to prevent the Big Ship BS PT from "sailing home to haven in sunny Palestine".  For Carey (having been teaching continental drift for years (which was effectively Plate Tectonics) and finding it not working) was proposing throwing the whole thing out - baby,bathwater and all - and advocating instead the most exciting development in geoscience up until that time and the one most in accord with the geological facts - and indirectly too a leg in to understanding the creation of mass which should have been of interest to physicists.  Instead and in protest, and in the face of ordinary common sense, they, the crew of the big ship, set out to invent a means of keeping everything within the limits of "gradual refinement", thereby reducing the wonder of geo-logic to ever-smaller nonsensical noises in the process.  In the face of the looming threat by HMS Carey they even raised the stakes by claiming a Nobel Prize for their own misbegotten geo-whatever behaviour. [Certainly it wasn't logic.]

============
 
So, .. is the Earth round or is it flat?  Is it getting bigger over time, or is it staying the same size like it is right now (considering the scale of geological time).  Does wearing it away make it bigger or make it smaller?
============

 And since Plate Tectonics has also devised a way to keep the arrow of geological time in the snapshot view of 'now' in perpetuity (and commit everybody to alternately keep sailing over an unreachable horizon or falling off the crows nest) where did it go 'wrong' to such an extent that as Azimov says, it only needs a little bit of tinkering to make it right?   [And, just by comparison (talking about the bugbear of "extra mass") how many theories do we need for light, .. gravity, .. electromagnetism .. the subatomic world in general,  ..  (and going the other way, astrophysics), when we know in our water (by a populist "belief in God") that everything is really connected as the same thing?   How many theories do we need for geology, the most 'carved in stone' hands-and-boots-on science of all?  (What about just one - that the Earth is getting bigger.)  Which is actually not a theory at all, but an observation tantamount-to-fact.  The theory part is the cause behind it - the pre-ordained 'domino' that who knows, .. could even be the one making us buggers too.  [I mean bigger(s).  "Biggering" (thanks Liam).]

And weather?  How many theories do we need for weather?

Thus tinkering with the 'little-bits that work' (nobody's saying right) 'themasknow' go forward, while bombasts-without-a-clue try to crash the barriers to understanding the natural world.  Is that it?

Cynical and offensive as this might sound (and so I guess it is), it is nevertheless the place you find yourself in when you realise the degree to which consensus squats like a dragon still, on what once was treasure, .. but which now is not. In very many things.

 Time tarnishes all but gold.  That's the trick. Recognising it, .. and putting it in the saddle-bags (/bank) for societal benefit.

 Read more?   Five mentions in the box below reminds me to post it.  We're going to sink this clapped-out rustbucket - beginning with erosion that helps to prove the Earth is getting bigger.  (But that's not where we started either.)

--------------

[That was posted back in March (2017).  Now it's the end of May, and with no comments in the box I'm beginning to think that readers don't like my style (undressing elephants in the room and painting holy cows black).  True, .. it's a busy job (there's so much of it around) but somebody has to do it.  And it doesn't seem to be attracting that much flack (yet).  At least like it should.  So we'll need to carry on with the nudity and the paint.  (It's the 'ignoring' thing, .. ignore it and it will go away (eventually) (and we needn't bother with it.) ]

Don't know if it will work out but I'm planning putting all the egg-on-face stuff in the book so I can surreptitiously bin it if need be or bring it out later as an "Ï told you so" once the lowing herd winds slowly o'er the lee and goes "Moo.o.o." .. and poos .. on its way to the trough, .. having got the message that there are pleasures to be had in 'milking' for all it's worth.  This is just the foundation layer to gauge interest.  I'm hoping people will be.  Somebody on the twitterfeed tweeted about how people's eyes light up when he tells them he's a palaeontologist, and then glaze over when he starts telling them about clams.  I liked that.  I told him he should try them with earth expansion.  People do say they are interested in geology, and I really do think they are (remembering my own introduction to it), but I don't see much evidence of it.  It's what I want to try to change.  Maybe I'm going about it the wrong way by casting aspersions on what they probably see as holy cows - Like NASA, the USGS, and all other educational institutions in the world ("winding slowly").

The point is trying to find a way into this story that people will find interesting.  Geology is not rocket science.  It's quite accessible.  Uniformitarianism versus Catastrophism are two big words that are guaranteed to lose people's interest, until perhaps they are faced with the reality of what they are getting at, namely a tsunami (that didn't happen last year - but might this year) or a hurricane the size of the Earth if it happens to be on Jupiter (that did) (and it's doing it all over again - worse than in living memory).  Or an avalanche of the sort that keeps burying people alive.  Or a Mountain getting blasted off the face of the Earth (that doesn't happen every day either), while here's me trying to interest them in the grain of sand that gets bounced on to the side of a bucket in my back yard each time it rains -  as a means of capturing *real* interest.  Wowser stuff (in my book!) because it captures the essence of time, the ineluctable relentlessness of gravity that oversees all the 'wow', .. and destiny.  The rain might bounce it up, but gravity drags it back down, just as it returns us to the soil once it's done with us, even if we go up in a puff of carbon dioxide global warming - the doing, that once done with the 'getting bigger', is done.

There's no telling the sorts of things that grab people's interest, nor what they really mean when they say they are 'interested', or why they are,  and what is it that makes something interesting to one person and not another.  They'll all go out and get themselves tattooed and studded with rivets and bellystuds (even some on the tongue) (for the palatable experience), .. shaven heads and a pair of bovver boots, ..  or whatever is the hot fashionable branded mark of the day, but not everybody is interested in sand grains that bounce, or a moon that does, or knowing about Earth expansion, even if there are fewer steps in it than has you linked to the POTUS.  (The what?)  The comments boxes on these pages vouch for it.  [What's a potus anyway?  Sounds suspiciously like having something to do with 'plants' or 'training'. or :-

"??POT??  ??US??  Oh no officer! NOTUS"
 "That's another one.  Obstructing a Pleece Officer in the execution of his dooty."

Oh, .. 'fashion', ..  that's 'belonging' is it?  Is that different from showing an interest?  Yes, it is.  Interest is the awakening of the apartness of the self from the ylem of existence, .. the thin edge of the wedge that sets you apart from the crowd.  'Showing it' is getting towards the thicker end, and getting irretrievably 'fixed'. It's the dichotomy of security (comfort) and insecurity (fear) wrapped up as one.

I'm sure David Attenborough could make the drama of 'clams' quite interesting,  He does it here by exciting our fear of the chase (not easy, .. with a clam), but I'm also wondering where he might then start with a script for Earth expansion, it being so old-hat already. What's that?  You didn't get it in school?  No, I'll bet not.  And won't either for another century either.  *That* is what I find interesting - what is it that leads the herd in one direction then another,  while all of them think (/know) that they are individuals.  Which way round is *that* domino? [1] [2]

Science is a particular case in point when it comes to interest and that wedge-edge.  Despite the hype about innovation and the flaunted desire to be "first to discover"  there is nevertheless an imperative to belong (consensus pages [1] [2]).  Here's what Gordon MacDonald ("the whizz-kid of geophysics"), once of the big ship but who got handed the black spot on behalf of the crew, had to say on the matter when cast away on the desert island of Coventry :-
"In all science there is a strong 'herd instinct.'  Members of the herd find congeniality in interacting with other members who hold the same view of the world.  They may argue vigorously about details, but they maintain solidarity when challenged or criticised by those outside their comfortable herd.  If individual scientists stray too far from the accepted dogma of the day, that of the herd, they are gently (or not so gently) ostracised..  The herd instinct is strengthened enormously if the paymasters are members of the herd.  Strays do not get funded and their work, sometimes highly innovative, is neglected as the herd rumbles along.  When leaders of the herd decide to strike out in a new direction, the herd often follows.  Before the 1950's the North American herd of geologists found it comforting and amusing to ridicule those foreign geologists who advocated continental drift. In the early 1960s, Harry Hess, Tuzo Wilson, and Bob Dietz, all respected leaders of the North American geologist herd, decided to shift directions [Link - and scroll down to "Harry realised it had to be" - d.f.] and the herd soon followed.  By contrast, if the innovators are not part of the herd it becomes very much more difficult, if not impossible, to change direction. Over the years I have seen many examples of the herd mentality in many fields of science."  [Gordon MacDonald in Oreskes, 2001, Plate Tectonics, an Insider's History of the Modern Theory of the Earth, p.125.)  ["Many examples of the herd mentality"]

Where were we?  Ah yes, about the crew not being interested in grave issues .

What the cook was trying to say before the crew got excited about dragons and the possibility of finding themselves sinking like stones and enmeshed in the seaweed ... was, .. that .. wherever we go in the world, and whether the land is mountainous or already flat, erosion is keep working towards making the Earth flatter than it used to be.  With time, and given enough of it, rugged lands get levelled. And by the same process that ensures our ghostly mariner crew is forever condemned to sail into the sunset or the sunrise or whichever star they care to follow, they never seem to be able to reach the horizon no matter how long or how far they keep sailing.  And likewise no matter how many nice sandy beaches they pass telling of material eroded from the land, or houses falling into the sea testifying to the speed of it, or maidens decorating them, somehow the land always seems to remain much the same.  It is always 'there'.  The continents never seem to become entirely a beach - raising the further question, "How old are the continental shelves?" - and sundry others regarding their distribution.
Erosion (and the speed of it - sometimes):-  mountains,  storms, rivers, sandy beaches.   Houses falling into the sea  
 ... all of them confirm the veracity of the cook's story (about the Earth keep trying to be flat(-er) than it used to be (=> Google Earth and fractures).

________________


Although the crew might not be inclined to mull over the question of beaches, it did occupy Arthur Holmes, who essentially begins his very influential textbook (Principles of Physical Geology, 532pps) with it, saying (paraphrasing here), .. "Why haven't the continents been eroded to what, essentially, is a great big beach? Why is there still land to speak of, .. to write home about, .. to go on holiday to (.. 'to the mountains' /rivers /seaside")?

This is also the same very same question (re. crustal elevation, erosion and flatness) that in considering the merest aspects of global deformation I find offers me the best leg-in to this story too.  It is rather gratifying to find this common ground.  There is no doubt that Holmes must have mulled over it too before choosing it as his 'thread-of-choice'.

But he wants to dismiss it - and get on to the reasons why there is still land (to be eroded).  I want to unravel and examine it.

If we didn't know about gravity being the force that keeps us attracted to the planet we might regard erosion in its various climatological /weather ways as being the most prosaic expression of gravity, whose hands, fingers and everything else is all over this story, much like the sun is all over the question of 'seeds' (and religion) (and global warming) (and people in Britain going on holiday to Mediterranean lands) - and so on (incl. 'babes on beaches').  To see the various connections however can be challenging, even verging on madness.  And in that comparison I find more than a little amusement in returning to undergraduate years when our geology professor would enjoy himself by smugly reminding us 'men-of-stone'] in his various ways, "You hard-rock fellows," (wowed by folds and faults and with no concern for the lie of the lovely land), .. "you return to geomorphology - eventually".

He's right.  A Welshman (of palaeontological and stratigraphic persuasion) whose interest in geology related more to planation surfaces and the development of landforms, river capture, erosion surfaces and the like as these affected simple vertical ('normal') adjustments of the land to gravity, he was entranced by the manner in which the sea could strip back the land flatter than a pancake [1] [2] (Dover or Suffolk and Hutton's unconformity], while we (men of stone) (being 'men' already) could only see in his fixations the more obvious attractions of beaches,  before soldiering on to the pub for more 'reality'.


Holmes puts the beach question as a statement):-
 "Just how it comes about that continental land exists at all is still an unsolved problem."
.. and a few pages later (p.26), a little differently :-
" It follows that there has been ample time, since land and sea came into existence, for Britain, and indeed for the highest land areas, to have been worn down to sea-level over and over again.  How then does it happen that every continent still has its highlands and mountain peaks?
We dwell on this for two reasons. Firstly because Holmes was an original thinker and therefore a good guy, and, with sixteen reprints of his book ("Principles ..") by the time Plate Tectonics began to get underway in America, he was far and away the foremost populariser of that model regardless of its (supposed) 'neglect' there (Oreskes intro)  and <"never thought to read"> (believe that one if you like).  So the concepts outlined in his book re. convection mark the point of departure we need to return to in order to progress this story. Secondly, because erosion leads inevitably to considerations of Earth expansion.

Given the wranglings over land bridges and mechanisms of continental displacements in Holmes's day this second reason may actually have very well been the reason why he steered away from examining further than he did the 'beaches' implications of such protracted erosion, preferring instead to address what he saw as the reason for the elevation of land in the first place.  This (beaches) is the route that we will go down.

Crustal compression (and folding) (and the upwards movement of the crust that accompanied both) already meshed with popularly accepted norms of crustal movements.  Crustal extension, erosion, or anything else that led to considering an Earth that was getting bigger was then .. well, .. just a bridge too far.  The pall of ridicule could easily extend to his first book, The Age of the Earth (1913) for which he was (and still is), lauded.

However it was a path that Holmes himself appears to express some misgivings about, even as his book "Principles .. "  had already (by1953) run to thirteen printings :-

"I have never succeeded in freeing myself from a nagging prejudice against continental drift; in my geological bones, so to speak, I feel the hypothesis as a fantastic one", adding however, "Yet there are weighty reasons enforcing us to recognize it as true". (Holmes 1953 in Cherry Lewis - reference needed).
It is not clear if this is a ploy or not.  Feigning prejudice towards his own stated views on the one hand in order to augment the argument of the other is certainly a way to soften up the opposition, but by proposing deformation by the dual behaviours of compression and extension arising from mantle convection he was (for the times) certainly providing a fair working solution to Wegener's intractable problem of mechanism that many were grappling with.

So, .. 'beaches' ( and erosion).  This is the point to which we must return in order to appreciate the proper role of gravity in crustal deformation, for just as weather in its various guises of ice and snow, wind and rain acts on fractured brittle rock, and gravity transports it to (wherever), so heat and pressure deep in the Earth's crust help to equilibrate gravitational inequalities arising from changes in the Earth's curvature as it gets bigger (link).  In just the same way as 'beaches' are derivatives of the action of weather on high ground transporting the detritus 'sideways', so folds deeper in the crust are expressions of gravitational slumping of the whole in response to curvature change.

Which is the point the cook was going to make before the storm blew itself out -  that erosion, "keep making the Earth flatter than it used to be" translates geologically (with time) into 'keep making it less round' (than it used to be).  And more round => less round means decreasing surface curvature.  Which means (in turn) increasing its radius.

                  Which means, .. (drum roll & shazamm) .. making the Earth bigger.
                 Time + Gravity =  'Roundness / Flatness'  => scale + erosion =  Bigger.

[Cop that one with yer Big Idea (spun like fluff from the navel), and yer scientific method of measuring, and yer experiment.] [And don't forget geological time as this is expressed as the eternal, day-after-day, uniformitarianismily nice sunny days on placid beaches (with babes on) and the storms and tsunamis that no-babes lighthouse keepers have to put up with.]

See?  If you just think about it, just the very fact that erosion is *still* happening taken in the context of what we know of erosion in the geological record) (Holmes quote above) and global deformation generally (particularly the universal fracturing of the crust), (and every connected thing to Earth's gravity and rotation (that 'sun-and-the-seed' - and everything in between - thing) tells us that the Earth must be getting bigger.

Or does it?  How flat is flat?  What is the scale at which flat becomes round?  Or is the flatness we're seeing always round?  And what if we do something exceedingly clever with 'the method' and the plate spinning and the number-juggling and consider the flatness as small increments in roundness and sum them all up (as flatness) to roundness?

Clever, huh?

Nope. Not allowed. You have to look at it in its wholeness - holistically.  That is, not in itself (reductively), nor even assocatively with its nearest conjunctive conbobulation, (yes, it is likely to be a con) but outwardly in relation to everything of which it is a part, i.e., where it fits in the geological picture as a whole.  That is, in as great a context as possible.

Fig. 3.  Rock, seriously fractured (and a very little bit round) being eroded on a not very sunny day.   Preikestolen cliff :-: fair youth, because it maketh thuth a nithe point - about nothieth, thcale and tentatively looking over the edge of a cliff. [and more , while paying attention to the ruggedness of the land in the foreground and ignoring the flatness of it in the background. (and no, flatness is not a trick of distance [1] [2].]
So, .. by three things (and thirteen printings of his book) Holmes leads us to considering :-
1.  Erosion (which can be considered a sort of 'granular' falling of the land.
2.  Uplifting land (by folding and /or epeirogenesis, i.e., continent-wide uplift of land by mantle 'geotumors'.
3.  Falling sea-level.  Impressively by isostatic rebound in polar climes by the supposed removal of ice sheets.
... and takes us to considering the connection between erosion and isostacy as a mechanism for establishing gravitational equilibrium and his later expression of doubt (Fig.4), reasons for which we shall attempt to clarify as we go.


Fig.4 "Mind the Gap".   Arthur Holmes, getting 30km of crustal inconvenience out of the way on p.33 so he can deal with isostacy and lay the groundwork for mountain building and folding for the next ~500 pages.  The zig-zaggy 'gap' of 30km is the bit we're interested in here, which is the zone of subcrustal brittle and ductile ('solid rock') dislocational equivalent of the 'denudation and depositional adjustment' happening higher up in the crust.

 But what he appears to be missing (i.m.o.) (and intentionally or not), is that just as erosion rubs the mountain away by cascading avalanches of rubble lubricated by ice and snow, rivers and rain (Fig.1), so the whole mountain and the crust may be constrained to move on its partially melted mantle substrate, or indeed on any lubricated interface in the stratigraphic pile, but especially between the crust and the mantle and between the lithosphere and the asthenosphere.  The Earth might be 'flat' (like a plate) but it is also round.  What is gravitationally happening 'upstairs' in the crusty bouldery gravelly sandy soil being transported to some faraway lake or sea, is (i.m.o.) also reasonably happening 'downstairs' in the nether regions in the crust as its entirety is made to recover gravitational equilibrium as its curvature changes.


All of which is a reminder about a 'flat Earth' becoming more round, and that it's a "scale thing", and that with the inclusion of time the whole space and all that is in it changes to reveal other things - in the same way that very nice picture by Sian Monument has captured the connection between the sun and the imperative and continuity yet the fragility of life, and the 'madness' that some would say accompanies seeing it.  As it surely is if there is no anchor to attach it to.  Seeing beauty /God in nature (and in life) is one thing, just seeing the Earth as getting bigger is no more than common sense - which is what science is all about, when we think about it - the destination of all enquiry (getting the dominoes round the right way, in the right order and at the right scale). 
"Everything's easy, .. when you know how."  (~my dad.)

(This concludes intro on grav. collapse (I think).   Goes to :-
1.  Holmes and folding and 60+ reasons why Plate Tectonics is wrong
2.  Segues to extended section on gravitational collapse. 

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