Posts Tagged ‘Geologie’

Leon Retief. Gedugte geoloë en gedigte Geologie

Monday, November 11th, 2013

 

Op die kruin van die Sunwapta-pas in die Rockies:

 my vrou Lesli kyk terug na die pad wat ons so pas gery het.

 

Gedugte geoloë en gedigte Geologie

 

 We find no vestige of a beginning – no prospect of an end. James Hutton (1726-1997)

 

The Geology of Norway

 

I have wanted there to be

no story. I have wanted

only facts. At any given point in time

there cannot be a story: time

except as now, does not exist.

A given point in space

is the compression of desire. The difference

between this point and some place else

is a matter of degree.

This is what compression is: a geologic epoch

rendered to a slice of rock you hold between

your finger and your thumb.

That is a fact.

Stories are merely theories. Theories

are dreams.

A dream is a carving knife

and the scar it opens in the world

is history.

The process of compression gives off thought.

I have wanted

the geology of light.

 

They tell me despair is a sin.

I believe them.

The hand moving is the hand thinking,

and despair says the body does not exist.

 Something to do with bellies and fingers

Pressing gut to ebony,

thumbs on keys. Even the hand

writing is the hand thinking. I wanted

speech like diamond because I knew

that music meant too much.

 

And the fact is, the earth is not a perfect sphere.

And the fact is, it is half-liquid.

And the fact is there are gravitational anomalies. The continents

congeal, and crack, and float like scum on cooling custard.

And the fact is,

the fact is,

and you might think the fact is

we will never get to the bottom of it,

but you would be wrong.

There is a solid inner core,

fifteen hundred miles across, iron alloy,

the pressure on each square inch of its heart

is nearly thirty thousand tons.

That’s what I wanted:

words made of that: language

that could bend light.

 

Evil is not darkness,

it is noise. It crowds out possibility,

which is to say

it crowds out silence.

History is full of it, it says

that no one listens.

 

The sound of wind in leaves,

that was what puzzled me, it took me years

to understand that it was music.

Into silence, a gesture.

A sentence: that it speaks.

This is the mystery: meaning.

Not that these folds of rock exist

but that their beauty, here,

now, nails us to the sky.

 

The afternoon blue light in the fjord.

Did I tell you

I can understand the villagers?

Being, I have come to think,

is music; or perhaps

it’s silence. I cannot say.

Love, I’m pretty sure,

is light.

                You know, it isn’t

what I came for, this bewilderment

by beauty. I came

to find a word, the perfect

syllable, to make it reach up,

grab meaning by the throat

and squeeze it till it spoke to me.

How else to anchor

memory? I wanted language

to hold me still, to be a rock,

I wanted to become a rock myself. I thought

if I could find, and say,

the perfect word, I’d nail

mind to the world, and find

release.

The hand moving is the hand thinking:

what I didn’t know: even the continents

have no place but earth.

 

These mountains: once higher

than the Himalayas. Formed in the pucker

of a supercontinental kiss, when Europe

floated south of the equator

and you could hike from Norway

down through Greenland to the peaks

of Appalachia. Before Iceland existed.

Before the Mediterranean

evaporated. Before it filled again.

Before the Rockies were dreamt of

And before these mountains,

The rocks raised in them

chewed by ice that snowed from water

in which no fish had swum. And before that ice,

the almost speechless stretch of the Precambrian:

two billion years, the planet

swathed in air that had no oxygen, the Baltic Shield

older, they think, than life.

 

So I was wrong.

This doesn’t mean

that meaning is a bluff.

History, that’s what

confuses us. Time

is not linear, but it’s real.

The rock beneath us drifts,

And will, until the slow cacophony of magma

cools and locks the continents in place.

Then weather, light,

and gravity

will be the only things that move.

 

And will they understand?

Will they have a name for us? – Those

perfect changeless plains,

those deserts,

the beach that was this mountain,

and the tide that rolls for miles across

its vacant slope.

 

         Jan Zwicky

 

Wanneer mens sekere wêrelddele besoek, en in Kanada veral veral Nova Scotia, die Rockies en Newfoundland kan mens nie help om te wonder oor die geologiese agtergrond van die tonele wat mens gadeslaan nie. Waarom lyk die landskappe soos hulle lyk? En as mens die vraag geografies verder voer: waarom lyk die oppervlak van die aardbol soos dit lyk? Waarom word sommige verwante gesteentes duisende kilometer uitmekaar aangetref? Wanneer mens dieper begin delf, nie net in die geologie op sig self nie maar ook in die geskiedenis van hoe ons tans weet wat ons weet dan kom mens af op ‘n fassinerende maar grootliks onbekende stukkie geskiedenis van die natuurwetenskappe, geskiedenis van dinge wat ons vandag as vanselfsprekend aanvaar maar wat destyds die onderwerp van hewige meningsverskil was.

 

Fjord in die Gros Morne National Park in Newfoundland.

Drie mense het ‘n reuse-bydrae gelewer op die gebiede van biogeografie en geologie: hulle het die fondament gelê vir een van die belangrikste begrippe in geologie, fundamenteel tot hierdie vakgebied en ons verstaan van die planeet waarop ons leef:  plaattektonika, oftewel sogenaamde kontinentale dryf. Die eerste was Alfred Russel Wallace, net een “l” in sy tweede naam as gevolg van ‘n spelfout toe sy geboorte geregistreer is. Meeste lesers van Versindaba is seker bewus  van sy bydrae tot die ontstaan van die evolusieteorie maar hy het ook op ‘n ander gebied diep spore getrap, te wete biogeografie, ‘n vakgebied wat nie net van integrale belang is vir die studie van evolusie nie maar wat ook jare na sy dood sterk bevestiging gelewer het vir plaattektonika.

Alfred Russel Wallace (1823-1913)

Wallace se naam leef vandag voort in ‘n denkbeeldige lyn wat Indonesië naastenby in die helfte verdeel. Eilande aan die weste van hierdie lyn sluit in Sumatra, Borneo, Java en Bali, aan die ooste lê onder andere Lombok, Sulawesi en Timor. Daar is sedertdien ook twee ander lyne in daardie gebied getrek maar dis nie nou nodig om daaroor uit te wei nie.

Die Wallace Lyn

Tydens sy omswerwinge het Wallace opgemerk dat die dierelewe in die eilande van die westelike deel van die argipel ooreenstem met die fauna in kontinentale Asië terwyl die eilande aan die oostekant weer diere het soos wat in Australië aangetref word. Die skeidslyn tussen hierdie twee groepe fauna is later na Wallace vernoem. Wat hom veral getref het was dat sommige van die eilande met ooreenstemmende dierelewe  ver van mekaar geleë was terwyl ander wat weer naby aan mekaar was geheel en al verskillende spesies bevat het. Dit was veral opmerklik in die eilande Bali en Lombok wat deur slegs 35 kilometer seewater geskei word. Sy bevindings is op 3 November 1859 in sy afwesigheid aan die Linnean Society voorgedra, sewentien maande na Darwin se voordrag oor evolusie. Terwyl hy nie ‘n duidelike verklaring vir hierdie verskynsel kon gee nie het hy wel gespekuleer: “Facts such as these can only be explained by a bold acceptance of vast changes in the surface of the earth”, en hy praat ook van ‘n “great Pacific continent (which) probably existed at a much earlier period.”

Dit het meer as ‘n eeu geneem voordat daar ‘n verklaring vir Wallace se lyn gevind is. Ek dink dat hy baie in sy noppies sou wees as hy kon weet watter noue ooreenstemming daar is tussen die lyn wat hy getrek het en die grense van die tektoniese plate soos later vasgestel. Eone gelede was die gebiede waar Wallace sy ekspedisies onderneem het se posisies heeltemal anders as vandag en kon diere vrylik migreer omdat sommige van die betrokke eilande deur landbrue verbind was. Daar was egter geen sodanige brue tussen die plate self nie. Met verloop van tyd het die bewegings wat deur die plate veroorsaak is tot gevolg gehad dat die eilande nader aan mekaar beweeg het om uiteindelik in die posisies te lande te kom waar ons hulle vandag vind.

Wallace was egter nie die eerste wat gewonder het oor “vast changes” nie. Francis Bacon het al in 1620 geskryf oor hoe die vastelande “pas” en die Comte de Buffon het in 1778 ook oor hierdie verskynsel gespekuleer. ‘n Jaar voor Wallace se voordrag het die Fransman Antonio Snider-Pellegrini  ook vermoed dat die kontinente eens op ‘n tyd saamgevoeg was in ‘n superkontinent wat hy Pangea genoem het, na die Grieks vir “totaal” en “Gaia’ vir moeder aarde. Wikipedia se stelling dat hierdie woord eers in 1927 geskep is tydens ‘n kongres waar Wegener se teorie bespreek is (meer oor hom en sy teorie later) is verkeerd. Dit was in elke geval nie rocket science om te sien dat die buitelyne van sommige kontinente pas nie en met verloop van tyd is uitgewerk hoe Pangea destyds daar uitgesien het. 

Pangea

Wallace se spekulasies ten spyt was die algemeen aanvaarde opinie destyds dat kontinente slegs in vaste vorms bestaan en dat hul morfologie alleen verander wanneer dele van vastelande of eilande onder die oppervlak van die see verdwyn of weer bo seevlak verskyn. Die eerste persone wat met meer as net spekulasies te voorskyn gekom het was Alfred Wegener en Alexander du Toit.

Alfred Lothar Wegener (1880-1930)

Alfred Wegener was ‘n weerkundige. Dat hy geen formele opleiding in geologie gehad het nie het heelwat weerstand uit geologiese geledere tot gevolg gehad maar ek vermoed dat die kopskuif om te kan aanvaar dat kontinente in werklikheid van posisie kan verander vir baie geoloë nie maklik was nie. Hy het opgemerk dat daar besliste diskontnuïteite bestaan (wat ek nie verder gaan bespreek nie) in die fossielrekords wat in verskillende kontinente aangetref word. Verdere oorweging sowel as sekere geologiese waarnemings het hom laat besluit dat hierdie probleem elegant opgelos kan word as die kontinente in die jaar toet as een groot superkontinent saamgevoeg was.

In 1915 publiseer hy “Der Entstehung der Kontinente und Ozeane”, oftewel, “Die Ontstaan van Kontinente en Oseane” waarin hy postuleer dat kontinente in die verre verlede met mekaar in kontak was as een groot vasteland. Die boek het fel kritiek ontlok, meestal omdat Wegener nie ‘n meganisme kon voorstel wat die verskuiwing van die vastelande kon verklaar nie. Hierdie kritiek het hom skynbaar nie veel gepla nie. Volgens wat ek oor Wegener kon uitvind was hy ‘n besonder aangename persoon en hy het maar net doodluiters voortgegaan met sy weerkundige navorsing. In 1930 was hy deel van ‘n ekspedisie in Groenland en op 1 November het hy en sy metgesel Rasmus Villumsen ‘n reis vanaf die binneland na die kus aangepak. Nie een van die twee is weer lewend gesien nie. In Mei die volgende jaar is ‘n ekspedisie gestuur om na hul lyke te soek. Wegener se liggaam is in ‘n tent gevind waar hy in sy slaapsak lê, waarskynlik is hy in sy slaap dood as gevolg van ‘n hartaanval. Villumsen, so word gedink, het op sy eie die kus probeer bereik maar hy is ook iewers dood en sy lyk is nooit gevind nie. Wegener se liggaam kon nie afgevoer word nie en die ekspedisie het ‘n kruis opgerig langs sy lyk, op die gletser waar hy gesterf het. Iewers in die 1950’s het nog ‘n ekspedisie weer daar verby gereis. Die gletser het teen daardie tyd alreeds verder beweeg, die kruis en Wegener se liggaam was nie meer te sien nie.

 

Alexander Logie du Toit (1878-1948)

 

 Alexander du Toit, ‘n Suid-Afrikaanse geoloog, het Wegener se teorie entoesiasties ondersteun in “Our Wandering Continents” wat in 1937 gepubliseer is. Anders as Wegener was hy bereid om in polemieke betrokke te raak en hy en die beroemde paleontoloog George Gaylord Simpson het hewige meningsverskille in wetenskaplike joernale gehad. Ten spyte van Wegener en du Toit se pogings is die teorie egter nie algemeen aanvaar nie alhoewel dit tog ‘n betekenisvolle groepie ondersteuners gehad het.

Die bevestiging van Wallace, Wegener en du Toit se werk het uit ‘n onverwagte oord gekom. Keith Runcorn (1922-1995) was ‘n geofisikus met ‘n belangstelling in geomagnetisme en wat graag wou weet of die aarde se magnetiese veld met verloop van tyd verander het. Dit was reeds bekend dat gesmelte rotse (basalt, die produk van vulkaniese aktiwiteit) tydens die proses van afkoeling die polariteit en rigting van die heersende magnetiese veld, dit wil sê van die aarde, tydens die afkoelingsproses aanneem. Hierdie verskynsel staan bekend as remanente magnetisme. Interessant genoeg was dit Pierre Curie, Marie se eggenoot, wat hierdie verskynsel beskryf het en die temperatuur waarby rotse (of enige ander geskikte materiaal) die karaktertrekke van die omringende magnetiese veld aanneem staan bekend as Curie punt of Curie temperatuur.

Runcorn en sy medewerkers het in 1954 hierdie paleomagnetisme bestudeer, onder andere met behulp van ‘n sfeer bestaande uit 18,7 kilogram suiwer goud (wat deur ‘n baie skeptiese Koninklike Britse Munt aan hulle geleen is) en verskeie gesteentes in Engeland ondersoek. Hulle het gevind dat daar inderdaad betekenisvolle variasies was in die magnetisme van rotse in verskillende geologiese eras en dat daar slegs een van twee verklarings kon wees: óf die aarde se magnetiese pole het met verloop van tyd van posisie verander óf die kontinente self het verskuif.

As die magnetiese pole inderdaad sou verskuif het sou dit een stel bevindings gelewer het, as die vastelande wel van posisie verander het sou geheel en ander data gevolg het. Die paleomagnetisme van ander kontinente is ondersoek en dit het ondubbelsinnig getoon dat ja, die kontinente HET bleddiewil beweeg!

Die volgende ooglopende vraag was: hoe op aarde kon die kontinente verskuif het? Watter meganisme was hiervoor verantwoordelik? Al manier waarop dit kon gebeur sou wees as die seebodem uitsprei, maar empiriese gegewens was nie beskikbaar nie.

Ron Mason van Caltech is die persoon wat die antwoord gevind het. Hy was bewus van geklassifiseerde inligting wat tot die beskikking was van die VSA se vloot – navorsing oor ondersese magnetisme wat die vloot wou gebruik om aan hul duikbote skuilplekke te verskaf. Hoe op aarde hy dit reggekry het weet ek nie, maar hy het daarin geslaag om aan te sluit by Project Magnet soos die vloot dit genoem het. Hulle het ingestem dat ‘n skip van die Kuswag, die Pioneer, Mason se magnetometer agteraan die skip sleep terwyl dit waarnemings doen.

Die Pioneer het sy opnames begin in die Noord-Atlantiese Oseaan, naby Vancouver Eiland in Kanada. Vir maande het die skippie heen en weer gevaar teen ‘n konstante vyf knope per uur en die resultate, daar en elders, was onbetwisbaar: die seebodem was besig om stadig uit t sprei, soos ‘n laken wat tussen twee aaneenpassende matrasse ingedruk is en stadig uiteen getrek word. Uiteindelik was daar ‘n antwoord vir Wallace se waarnemings, vir Wegener en du Toit se teorie.

Groot ondersese riwwe is besig om magma na die seebodem se oppervlak te stoot en dit veroorsaak dat sommige kontinente weg van mekaar beweeg en in ander gevalle weer nader aan mekaar. Dit gebeur natuurlik nie net onder die see nie maar ook op vastelande, die Rockies en die Himalayas is voorbeelde van kontinentale plate wat teen mekaar vasgedruk word en berge tot gevolg het. Dit was vir my nogal iets besonders om op Signal Hill in St. John’s, Newfoundland te staan en te weet dat hierdie rotse onder my voete eens op ‘n tyd deel was van gesteentes wat tans in Marokko aangetref word.

Sedertdien is die grense van die verskillende plate gekarteer .

Kontinentale plate

Die volgende paar verse is deur Don Mckay wat in 2007 die Griffin Poësieprys gewen het vir sy bundel Strike/Slip waaruit ek ‘n paar gedigte gaan plaas, maar eers sy voordrag by ‘n poësie voorlesing uit hierdie bundel:

http://www.youtube.com/watch?v=8XquE0jlUtU

Oor die term strike/slip, ek gaan dit maar verduidelik in die taal van die veroweraar (soos Engels in my prille jeug aan my beskryf is deur ‘n stok-horing ou omie wat in sy eie prille jeug aan die Anglo-Boere-oorlog deelgeneem het) want ek weet nie wat die Afrikaanse woorde is nie, indien dit bestaan: “ a strike/slip fault (in contrast to a thrust fault) is a high-angle fault along which rocks on one side move horizontally in relation to rocks on the other side with a shearing motion. Examples are the famous San Andreas Fault… the Great Glen Fault in Scotland and the Creek-Leach River Fault on Southern Vancouver Island.” Bogenoemde kom uit die notas wat Mckay hulpvaardig agter in sy bundel verskaf.

Resensente van Mckay se bundel skryf onder andere: “(he) walks us out to the uncertain ground between the known and the unknown, between names we have given things and things as they are… “ en” He walks the strike/slip fault between poetry and landscape, sticks its strange nose into the cols silence of geologic time, meditates on marble, quartz, and gneiss… “

 

DEVONIAN

 

Then someone says “four hundred million years” and the words

tap dance with their canes and boaters through

the spotlight right across the stage unspooling out the

stage door down the alley through the dark

depopulated avenues (for everyone is at the theatre) toward

the outskirts where our backyards bleed off into

motel

               rentall

                                stripmall

                                                       U-haul past willowscruff, past ancient

rusting mercuries along the lovers’ lanes the coyotes lure

our family pets down all those creekbanks where we

always did whatever anyway and left our bodies

blurring into brush the words slur into is it sand or

is it snow that blows its messages across

the highway through the headlight beam the dried-up

memories of water how the waves were how

the light that fell so softly through the depths was

intercepted by the lobe-finned fishes flickering among the

members of the audience still staring at the empty stage – four

hundred million years, yes, that’s a long

long time ago.

 

QUARTZ CRYSTAL

 

It rests among the other stones on my desk – small chunks of

granite, wafers of schist and slate – but it has clearly arrived

from another dimension. While the others call, in the various

dialects of gravity, to my fingers, the quartz crystal is poised to

take off and return to its native aether. Some act of pure atten-

tion – Bach’s D Minor concerto for instance – was hit by a

sudden cold snap and fell, like hail, into the present. Here it

lives in exile, a bit of locked Pythagorean air amid the pleasant

clutter of my study: simple, naked, perilously perfect.

 

Just the same, I can pick it up, I can number its faces, I can

hold its slim hexagonal columns in my fingers like empty

pencils. Who do I think I am, with my little dish of stones, my

ballpoint pen, my shelf of books full of notions, that I should

own this specimen of earth’s own artifice, this form before

mind or math, its axes reaching back to the Proterozoic, its

transparence the Zen before all Zen? It becomes clear that I

must destroy my watch, that false professor of time and free

its tiny slave. No problem – a few taps with a piece of Leech

River schist and the deed is done. But more is required. What?

Off with my clothes; how else but naked should we approach

the first of symmetries? Still insufficient, I can tell, although I

can also feel waves of dismay radiating from my reference

books, their mute embarrassments on my behalf. It is just the

sort of thing they feared might happen when the first stones

moved into the neighbourhood.

 

What next? Unfortunately, it appears I must set aside my

fingers and thumbs, those tricky manipulators who have so

busily converted rock to stone, who perpetrated the pyramids

and silicon valley: go clasp yourselves in the dark until you

learn to sit still and attend. More?

 

                          I give up baseball, with its derivative threes

                          and dreams of diamond.

                          I foreswear the elegant pairs and numbered runs

                          of minuet and cribbage.

                          I renounce the fugue. Dialectic,

                          I bid you adieu. And you,

                          my little poems, don’t imagine I can’t hear you

                          plotting under your covers, hoping to avoid

                          your imminent depublication.

 

While the crystal floats like a lotus on my palm, bending the

light from a dying star to dance upon my coffee cup this

fine bright Cenozoic morning.

 

‘n Varve (ek weet nie wat die Afrikaans is nie) is die jaarlikse neerlegging van sediment in gesteentes soos byvoorbeeld sandsteen.

 

VARVES

 

As I approach the high sandstone cliff with its stacked, individual,

terribly numerable varves, I think of George from group,

who was unable either to stop collecting newspapers or to

throw them out. He would describe – not without some pride,

or at least amazement at his own extremity – how his basement,

then living room, then bedroom had over the years

become filled in with stacks of the Globe and Mail, the Sun, and

the Glengarry News, all layered sequentially, until he was

reduced to living in the middle parts of his hallway and kitchen, his

life all but occluded by sedimented public time. Unlike George’s

collection (which of course I saw only in my mind’s eye), the

cliff’s is open to the eroding elements, so that bits have fallen

off to form a talus slope of flat, waferlike platelets at its base.

This one in my hand has been clearly imprinted by a leaf –

simple, lanceolate, probably an ancestor of our ash or elder.

Published but vestigial, gone like an anonymous oriental poet,

its image still floating on the coarse grains of summer.

           On the flip side, winter. Under the eyelid of the ice. How

often I thought of writing you, but the pen hung over the page.

All the details on the desk too shy to be inscribed. To settle, to

hesitate exquisitely, at last to lie, zero among zeroes. Much listening

then, but no audience. Rhetoric elsewhere. Language

itself has long since backed out of the room on tiptoe.

 

          Sometimes we believe that we must diagnose the perils of

the winter varve, and so do our talk-show hosts and shrinks,

who number its shades and phases as though it were pregnancy

renversé, with suicide at the end instead of a baby. As though

death were really death. As though the unspoken were failure.

Having misread even the newspapers. Having been deaf to the

music of the beech leaves, who will cling to their branches until

spring, their copper fading to transparency, making a faint

metallic clatter.

 

GNEISS

On the Isle of Lewis, be sure to stop at Callanish and spend some time

at the circle of standing stones erected by our neolithic ancestors.

          Touring Scotland by Automobile

 

There is not much raw rock in that sentence, with its persuasive

sibilants, not much scarp or grunt to remember the penalties

paid – the load of it, the drag, the strained backs, smashed

hands, and other proto-industrial injuries. It was not so long

before this, not one whole afternoon as measured in the life-

times of those upright slabs, that our ancestors had themselves

achieved the perpendicular. Now they required that some of the

rocks that comprised their island should stand up with them

against the levelling wind and eroding rain. And further, that

they should form lines leading to the most common and

hopeful of human signs – the circle of connection, of return.

They insisted that rock be stone.

 

           From across the heath it appears – and perhaps this testifies

to the brilliance of our ancestors as landscape artists – that

the amiable rocks have taken this on themselves, getting up as

you or I might do, as a sign of respect. By presenting themselves

in a rough circle they are simply performing a courtesy,

 like ships flying the flag of a country they are passing though.

They arrange themselves into an image of the eternity we

crave rather that the brute infinity we fear.

 

            But close up it is more likely to be the commotion of stress

lines swirling within each slab that clutches at the heart – each

stone a pent rage, an agon. None of the uniform grey of limestone,

that prehistoric version of ready-mix concrete, in which

each laid-down layer adds to the accumulated weight that

homogenizes its predecessors. Think instead of Münch’s The

Scream with its contour lines of terror; then subtract the face.

Or you could turn on the weather channel to observe those

irresponsible isobars scrawling across the planet. Imagine our

Ancestors tracing these surfaces, whorled fingertips to gnarled

rock, reading the earth-energy they had levered into the air.

They had locked the fury into the fugue and the car crash into

the high-school prom. They engineered this dangerous dance.

Better stop here. Better spend some time.