At the bottom (oldest) is the high grade metamorphic rocks. The conventional appraisal (not "God created with apparent age") is that these rocks were originally sediments that were deeply buried and subjected to quite high temperatures and pressures. High pressure means deep burial - The pressure is the pile of material on top.
Oh I completely agree. And as you say, of course they were originally sedimentary, which is indicated by the sedimentary strata of the Supergroup for one thing. And all those rocks were buried under three miles of strata from Cambrian to Holocene, that's pretty deep, and that pressure generated heat along with the heat from the volcano whose magma fingers are seen in the cross sections extending up into the schist, and which was obviously also the source of the granite alongside the schist, also formed by the pressure of the weight of the stack above. Yes, we agree absolutely, isn't this fun?
Now I don't know the metamorphic grade of these rocks (nor am I a metamorphic petrologist) , but I must think that the burial depth was of the order of many miles.
Oh so do I, and the strata above were laid to at least three miles.
Then this many miles was eroded off (lots of time) to expose the metamorphics to being at the surface. This surface would become the non-conformity.
Well, sadly, now we must disagree, because I believe the Great Unconformity was formed beneath the stack of strata that we see still in place in the Grand Canyon, and the "erosion" is the evidence of friction between those rocks and the underside of the Tapeats when a tectonic force came low from the side and rammed into the then-sedimentary rocks, pushing them up against the Tapeats, which is evidenced by the uplift just above the Supergroup that extends all the way to the Kaibab into which the canyon was cut, also causing the whole shebang to slide for a quarter of a mile at that contact, causing the erosion, and causing the quartzite boulder to move that distance embedded in the Tapeats sandstone {abe: Actually it was the lower rock, not the boulder, that moved}. The only part of the rocks beneath the Tapeats that isn't confined completely beneath the Tapeats is the extra hard Shinumo quartzite which was apparently hard enough to penetrate through the Tapeats while all the other sediments weren't hard enough to do that and so remained confined below. Where the Shinumo is exposed above the Tapeats perhaps it should be understood as the cause of the disappearance of the strata above the Tapeats at those locations.
At the same time all this was going on the pressure and the heat turned most of the sedimentary rock beneath the Great Unconformity into schist and granite. This makes a LOT more sense than the idea that those hard rocks were eroded down to near horizontality.
The metamorphics were then re-covered by the supergroup sediments, which were in turn folded/tilted and faulted, and then eroded. Again, much time needed. This surface that would become the angular unconformity (and it isn't a fault).
The problem with this idea that the Supergroup re-covered the metamorphics is that the actual Supergroup is only present beneath the Great Unconformity in a very limited area while the great majority of the rock beneath the GU is granite and schist. The schist had to have been the result of the heat and pressure transforming the rest of the Supergroup type strata into metamorphic rock, and then there was the magma from the volcano beneath it all that was released by the tectonic force and whose heat contributed to the formation of the schist and rose up to form the granite also seen all over the Grand Canyon beneath the Great Unconformity, and for that matter all over the continent as well and even the world. That all this happened after the strata were in place is shown by the magma that spills out over the exposed layers above, in the Grand Canyon but also at the far north end of the Grand Staircase where the exposed surface is way up at the top of the Claron.
And then you've got the Supergroup being tilted and faulted, but you don't offer an explanation for what caused that. Just a local event of some sort? Don't you think my theory is so much more elegant and explanatory? Then what you explain as surface erosion taking a Looooong long time, a major tectonic event explains easily as friction caused by an enormous jolt from the side pushing it upward while sliding it under the Tapeats, and tilting and faulting it all at the same time, pushing up the entire stack of strata above it all into the Kaibab Uplift, taking a lot less time, while also at the same time releasing the magma from beneath which metamorphosed much of the strata once part of the Supergroup, into schist, and forming the granite as well.
Isn't it lovely?
The supergroup was then covered by Paleozoic and later sediments, of a wide range of depositional environments. More time taken.
Not just the Supergroup, which really doesn't cover much territory, but also the granite and the schist, which somehow or other got planed off to near horizontality by mere surface erosion? But in the conventional paradigm time is magic.
Na, the whole column of Phanerozoic strata was already there when the tectonic force hit, causing not only all the goings on beneath just described but also shaking things up in the upper reaches of the strata, breaking them up down to the Kaibab as the Flood was receding, which washed them all away, much of it into cracks that became the Grand Canyon, and also removing huge amounts in the Grand Staircase area, leaving only the cliffs known as the stairs.
SO elegant, SO explanatory, SO comprehensive. No "depositional environments" and relatively brief time.
The big picture - The Earth's continental crust is a 3 dimensional mosaic of sedimentary, igneous, and metamorphic rocks, all to some lesser or greater degree deformed or otherwise modified by folding, faulting, metamorphism, and other processes.
I agree.
To attribute this vastly complex 3 dimensional mosaic to being entirely the result of a single flood event is silly.
The Big Picture based on the Flood is that there was a lot more to the Flood event than a lot of water. The entire Earth and even the cosmos were all undergoing massive trauma. Events on the sea floor occurred along with the prodigious rain that began the eventful year, the water rose and all life on the land died along with much in the oceans, and was buried in the sediments scoured off the land and churned up from the depths, and at or toward the end of it all the continents split, the plates started moving, volcanoes were released by the movement, the water started receding, mountains started being pushed up by the continental resistance to the movement of the plates deforming much of the just-laid sedimentary strata and so on and so forth.
ALL THE STRATA of the Geologic Column were already in place when this massive upheaval started to occur at the end of the Flood. So much of it was broken up and washed away leaving partial stacks that you misread those areas as caused by different events. Salts in the layers over time collected at the bottom, causing the whole stack of strata to sag into hammock shape, and when enough salt had accumulated it began rising as salt domes up through those strata -- the timing since the Flood is right for that to happen, but millions of years not. There are other places where you can see the whole range of rocks from Cambrian to at least Permian all tilted as a block. Angular unconformities HAD to have been formed at this time too, just had to, and the later tectonic force that pushed up the Supergroup forming the Kaibab Uplift is the best explanation for all of them, buckling part of the strata beneath a weak spot in the stack, often leaving part of the upper stack still horizontally in place. The worldwide extent of the Great Unconformity fits perfectly into this picture.
Yes, the Grand Canyon stratigraphy IS representative of the Earth as a whole.
Edited by Faith, : No reason given.
Edited by Faith, : No reason given.
Edited by Faith, : No reason given.
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