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Author Topic:   Geologic Column
NosyNed
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Posts: 8595
From: Canada
Joined: 04-04-2003
Member Rating: 2.2


Message 1 of 43 (38531)
05-01-2003 2:34 AM


There are a number of claims made by creationists about the geologic column.

Let's look at them one at at time.

Also, I didn't get the idea you knew this already (though I may be misunderstanding your first comment) but they DO NOT date fossils by radiometric decay--fossils are dated based on what layer of rock they are found in

from www.evcforum.net/cgi-bin/dm.cgi?action=msg&f=5&t=228&m=15#15 -->www.evcforum.net/cgi-bin/dm.cgi?action=msg&f=5&t=228&m=15#15">http://www.evcforum.net/cgi-bin/dm.cgi?action=msg&f=5&t=228&m=15#15

in reply
You're caught in a misconception about dating with index fossils.

quote:
--------------------------------------------------------------------------------
Also, I didn't get the idea you knew this already (though I may be misunderstanding your first comment) but they DO NOT date fossils by radiometric decay--fossils are dated based on what layer of rock they are found in
--------------------------------------------------------------------------------

That's true but misleading. The fossils are part of the characteristics of rocks which were recognized centuries ago. They helped to sort out the layering. Some fossils are very restricted to what layers they are found it and make this easier but other characteristics of rocks help. This produced the geologic column with relative ages. Only relative.

A long time after that various methods became available to date the layers directly. This put absolute dates on the layers.

Now since the geologic column had already been sorted out and the fossils which could be used as index fossils for a layer already been determined it is easy to date a layer by looking the fossils. In any case where there is doubt about a date a direct dating can be done. The fossils help tell what layer you are looking at. The index fossils anyway. These layers are dated separately. Any other non-index fossils in the same layer can then be assigned the same date.
Got that?

Links:
http://earthsci.org/teacher/basicgeol/geotim/geotim.html
http://www.geol.umd.edu/~tholtz/G104/104Y2K/104Lec04.htm

I'll leave this for further posts with one note for the creationists to answer:

Historically the geologic column was worked out (starting with creation scientists) and the relative ages were assigned. Much, much later the absolute ages were determined with different radiometric methods.
Why did the absolute ages correlate with the relative ages previously worked out?


  
Minnemooseus
Member
Posts: 3256
From: Duluth, Minnesota, U.S. (West end of Lake Superior)
Joined: 11-11-2001


Message 2 of 43 (50721)
08-16-2003 3:35 PM


I happened to rediscover this topic. Right now, I don't have time to pursue it further, but I thought I'd give it a bump.

quote:
Links:
http://earthsci.org/teacher/basicgeol/geotim/geotim.html
http://www.geol.umd.edu/~tholtz/G104/104Y2K/104Lec04.htm

The above are both nice introductions to geologic study methodology etc.

Perhaps Edge would be up to the task of re-outlining the difference between the textbook version of the geologic column, and the real world version of the geologic column. I know we've had some discussion of this in the past. In short, the textbook version is a timeline, which really says nothing about rocks. This is why there is a lot of truth to the statement "The geologic column only exists in textbooks".

Gotta go,
Moose


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edge
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Posts: 2539
From: Colorado, USA
Joined: 01-09-2002
Member Rating: 1.5


Message 3 of 43 (50728)
08-16-2003 4:16 PM
Reply to: Message 2 by Minnemooseus
08-16-2003 3:35 PM


Well...
...perhaps a quick treatment...

quote:
Perhaps Edge would be up to the task of re-outlining the difference between the textbook version of the geologic column,...

Actually, I have a text in front of me that shows 15 different geological columns for the Cambrian alone... I think what you mean here is the 'geological column as most YECs see it'. This is actually the Geological Time Scale as your first site points out quite well. There is basically one time scale. How it got filled with rocks is a different story. Every location on earth has its own geological column.

quote:
... and the real world version of the geologic column.

Yes, this (these) are the real story. They represent the actual rocks occurring at a given location, in order of occurrence. They essentially fill in the time scale 'trays' with rocks. In most cases, not all periods of the time scale are represented. This is not unexpected or a violation of some geological precept.

In fact, we expect gaps, some of them quite large. This is because of erosion or non-deposition of rocks in those gaps which we generalize as 'unconformities'. We know unconformities are real, because we live on one. There have been no significant sedimentary rocks deposited on the Canadian shield (for instance) for as long as anyone can remember.

quote:
I know we've had some discussion of this in the past. In short, the textbook version is a timeline, which really says nothing about rocks. This is why there is a lot of truth to the statement "The geologic column only exists in textbooks".

IF one equates the geological column with geological time scale, yes. However, that is only done by YECs as far as I know.


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NosyNed
Member
Posts: 8595
From: Canada
Joined: 04-04-2003
Member Rating: 2.2


Message 4 of 43 (86127)
02-13-2004 1:44 PM
Reply to: Message 3 by edge
08-16-2003 4:16 PM


A 60 second geologic primer
This is a bump for lunkhead.

I will try a quick summary.

In any one place in the world there may be a series of strata. These have particular kinds of rocks one a top the other.

Sometimes the layers are obviously "screwed up" as when a mountain range has risen and the layers are twisted and bent. However, even then the relationships may be intact. That is which layer is next to what layer.

When comparing layers from different places sometimes you find that a few of the layers from one place match up with layers from another. The nature of the rocks, the relationship between them, the kind of fossils in them and perhaps even some degree of thickness are the same. However, this new place may add (above or below) additional layers not found somewhere else.

If site after site (many 1,000's) are examined it becomes possible to find a clear pattern. Even without one place with all the layers it is clear what the sum of all strata would look like. (though there are places with all or a lot of it in one place).

All of this was done around two centuries ago.

Much, much later the technology became available to give absolute, rather than relative, dates to the layers.

Lo and behold, now pay attention, this part is important: The dates corresponded to the already determined order from deep down in the geologic column being old to high up being newer.

If anyone can doubt the validity of the overall result after that they have some serious information processing deficits.

Now the geolgists can please correct any big booboos I have made.

[This message has been edited by NosyNed, 02-13-2004]


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Bill Birkeland
Member (Idle past 44 days)
Posts: 165
From: Louisiana
Joined: 01-30-2003


Message 5 of 43 (92923)
03-17-2004 1:10 PM
Reply to: Message 4 by NosyNed
02-13-2004 1:44 PM


Re: A 60 second geologic primer
NosyNed wrote:

"When comparing layers from different places sometimes
you find that a few of the layers from one place match
up with layers from another. The nature of the rocks,
the relationship between them, the kind of fossils in
them and perhaps even some degree of thickness are the
same. However, this new place may add (above or below)
additional layers not found somewhere else.

If site after site (many 1,000's) are examined it
becomes possible to find a clear pattern. Even without
one place with all the layers it is clear what the
sum of all strata would look like. (though there are
places with all or a lot of it in one place).

All of this was done around two centuries ago."

This is a very true and important point. Some Young Earth creationists, i.e. Kent Hovind, don't understand that the concept of a Geologic Column was developed and the vast majority of its individual components were named before Darwin publicly presented his theory of evolution. This completely refutes the claims that the geologic column was constructed either based upon or assuming the validity evolution.

It is also important to note that the geologic column was constructed long before any methods of radiometric dating were developed. Thus, the development of the geologic column occurred independent of either evolutionary theory or radiometric dating. The use of fossils to date strata was practiced long before the possibility of radiometric dating was even conceived, Thus, the claim that radiometric dating and biostratigraphy are somehow circular reasoning is nothing more than sloppy, illogical, and illiterate reasoning on the part of Young Earth creationists. The relationship between radiometric dating, biostratigraphy, and the geologic column is discussed by Andrew MacRae in "Radiometric Dating and the Geological Time Scale" at http://www.talkorigins.org/faqs/dating.html .

The details about the how the geologic column was constructed can be found in:

Berry, W. B. N., 1968, Growth of the Prehistoric Time
Scale. W. H. Freeman and Company, San Francisco. 158 pp.

The history has been summarized in some posts to talk.origins, including "Re: Did GOD create man? - (Geologic Column, Polystrate Trees, etc.)" by Keith Littleton and posted on 2002-02-25 16:45:40 PST. The timeline for the development of the geologic column given in this talk.origins post is:

"1669 - Steno publishes on principle of superposition

1760 - Professor Antonio Vallisnieri first developed and
described and named the Tertiary and Quaternary Periods.

1795 - Alexander von Humboldt recognizes the "Jura-Kalkstein"
(Jurrasic) as a distinctive rock unit.

1815 - William "strata" Smith publishes "The Geological Map
of England and Wales." Based entirely on his own extensive
field work, this map combines the principle of faunal
succession and principle of superposition to correlate
outcrops of sedimentary strata."

(NOTE: William Smith's research is described in "The Map That Changed the World: William Smith and the Birth of Modern Geology" (HarperCollins) by Simon Winchester.)

"1822 - d'Omalius d'Halloy, reviewing extensive field studies
of others divides the Secondary rocks of the Paris Basin
into five groups. The uppermost of these he calls "Terrain
Cretace."

1822 - Conybeare and Phillips publish the "Outlines of Geology
of England and Wales. The Carboniferous and Cretaceous Periods
are first formally named.

1833 - H. P. I. Reboul publishes research that points out the
Quaternary Period as being typified by fossils of animals and
plants like those now living.

1833 - Lyell, on the basis of relative percentages of living
versus extinct fossils subdivides the Tertiary into Newer
Pliocene, Older Pliocene, Miocene, and Eocene. He examined
40,000 specimens from each of these units to determine the
relative percentage of living to extinct in each.

1834 - Friedrich August von Alberti after an intensive study
of rocks that constitute the salt deposits of Germany
publishes articles that establish the Triassic period as
having a distinctive fossil assemblage with a relative time
significance.

1835 - Adam Sedgwick and Roderick Murchison publish "On the
Silurian and Cambrian Systems, exhibiting the order in which
the older sedimentary strata succeed each other in England
and Wales. This publication, based upon years of field
work, by them officially names the Cambrian and Silurian
Periods.

1838 - Adam Sedgwick first introduces the concept of the
Paleozoic Era at a talk before the Geological Society of
London.

1839 - Leopold von Buch, based on field work going back to
1795, publishes "Uber den Jura in Deutschland." This
publication officially defines the Jurrasic Period and
divides it into upper, middle, and lower subdivisions.

1839 - Lyell renames "Newer Pliocene" as the "Pleistocene"
Epoch.

1839 - Adam Sedgwick and Roderick Murchison jointly propose
the Devonian Period based upon it unique fossil faunas and
principle of superposition which shows that it lies between
previously recognized periods. Contrary to false claims
made by Young Earth creationists, the recognition of this
period, as with the other periods, and its placement has
nothing to do with the relative complexity of fossils.

1840 - John Phillips first uses the terms "Mesozoic Era"
and "Kainozoic (Cenozoic) Era" in an article in the
"Penny Encyclopedia."

1841 - Roderick Murchison publishes paper which defines the
Permian Period. Again, age of this period is based upon
the relative position of these strata between Triassic and
Carboniferous Rocks. This publication is the direct result
of field studies in the Urals near Perm in Russia.

1854 - Heinrich Ernst von Beyrich recognizes and defines the
Oligocene Epoch.

++ (1858 - Darwin's first public presentation on his theory
of evolution) ++

1874 - W. P. Schimper recognizes and names the Paloecene Epoch.

1879 - Lapworth defines the Ordovician Period based upon
his studies of graptolite fossils in North and South Wales."

Of the major subdivisions of the geologic column, the Paleocene and Ordovician are the main significant subdivisions of the geologic column that were named after Darwin published his ideas about evolution as the Pennsylvanian and Mississippian are only North American subdivisions of the Carboniferous. Although individual subdivisions of the geologic column were first recognized mainly in Europe, geologists and paleotologists then went all over the world and studied outcrops to determine whether or not the fossils occurred within the same sequence elsewhere in the world as in Europe. As a result of this research and reconfirmed by innumerable later studies, these scientists found that they did as illustrated by Glenn Morton in "The Geologic Column and Its Implications to the Flood" at:
http://home.entouch.net/dmd/geo.htm

Finally, Kurt Wise, a well-respected Young Earth creationist paleontologist, had some quite interesting comments on the geologic column in:

Wise, Kurt P. (1986) The Way Geologists Date! in Proceedings of
the First International Conference on Creationism, Section 1, Vol. 2,
Walsh, R.E.; C.L. Brooks; and R.S. Crowell (eds.), Creation Science
Fellowship, Pittsburgh, PA.

On pp. 135-136, Dr. Kurt Wise stated:

"Years before Darwin published the "Origin of Species", geologists
had constructed a geologic column very similar to that used
today. As early as the late eighteenth century it began to be
recognized that fossils found below others in one area would be
found beneath the same ones in another area. By the late 1820's
Georges Cuvier had convinced most of the scientific world that
there was a certain inviolable order to the fossils of the world.
Although the types of rock did not always occur in the same
order, the fossils contained within them always would. It became
common to give names to suites of fossils which were always
ound together. Thus arose the names Cambrian, Ordovician,
Silurian, etc., that are found on the current geologic column.

When the theory of evolution was introduced, the order of the
geologic column was not affected appreciably. Since it is not
possible to predict the path of evolution, no change in the column
SHOULD have occurred with the acceptance of evolution -- and no
change did occur. The column also preceded by at least a century
any means of affixing absolute ages. The only methods of "dating"
available in the nineteenth century were those of superpositional
stratigraphy and biostratigraphy. Each of these methods yielded
only relative ages-- that is, younger, older, or the same age as
some reference rock or fossil. When radiometry was introduced a
method of assigning absolute ages had finally arrived. With it,
any defects in the column should have been quickly recognised. No
significant contradictions occurred between the column and
radiometry. Although this may be due to wholesale dishonesty in the
interpretation of radiometric dates, no systematic study has been
done to establish this. As a result, the radiometric dates must be
taken as strong evidence in support of the correctness of the
geologic column."

Progressive creationists, i.e. Dr. Georges Cuvier, accept the existence of the geologic column. Some of them explain it in terms of multiple periods of catastrophic extinctions and supernatural creation of new life forms by divine intervention, a view intensely disliked and considered heretical by many Young Earth creationists.

Yours

Bill

P.S. the editing done is to correct spelling, links, grammer, and so forth.

P.S.S. Someone needs to point out to Dr. Morris that "Sedgwick" isn't spelled "Sedgewick" as he does in his Acts and Facts article on the geologic column.

[This message has been edited by Bill Birkeland, 03-17-2004]


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Arkansas Banana Boy
Inactive Member


Message 6 of 43 (191848)
03-16-2005 12:12 AM


For Faith on Geologic column...
Perhaps instead of a new thread, a reborn old one with nifty links that speaks to the GC, where the old thread on "Evo Time Strata" was meandering before closure.

Also a link http://gpc.edu/~pgore/geology/geo102/intro.htm that outlines modern geologic concepts not too overburdening.

I'm off to work on the quality of my geologic puns.

ABB


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Faith
Member
Posts: 16985
Joined: 10-06-2001
Member Rating: 1.5


Message 7 of 43 (192164)
03-17-2005 4:53 PM
Reply to: Message 6 by Arkansas Banana Boy
03-16-2005 12:12 AM


Re: For Faith on Geologic column...
Thank you for bumping this. I love it. Back when I have more time.
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roxrkool
Member
Posts: 1491
From: Nevada
Joined: 03-23-2003


Message 8 of 43 (195249)
03-29-2005 4:42 PM


Something that has not been mentioned are intrusions. Intrusions are very much a part of geologic columns worldwide.

One can often determine whether the country rock (e.g., sedimentary rock) was lithified or not, was saturated with water or not, how deep the rocks were, etc., when intruded simply by examining the mineralogy and their associated textures, as well as the cross-cutting relationships.

Simply put, the priciple of cross-cutting relationships says that younger rocks cut older rocks, either via intrusion, faulting, or erosion; and by studying these relationships, we can extract depositional and intrusive histories of an area. Additionally, this principle is used to study vein systems, dike swarms, alteration history, etc.

Basically then, igneous rocks, because they intrude other rocks (i.e., country rocks), are therefore younger than the country rocks.

However, igneous intrusions can evolve over a period of time through fractionation, these magmatic changes can be reflected in associated and chemically-related dike swarm systems. The earliest magmatic composition might be more mafic rich and dikes reflect this. Younger and younger dikes might become progressively silica rich and again, dikes can reflect this. The oldest mafic dikes cut only country rock. The youngest silica-rich dikes cut everything else including dikes that are more mafic in composition.

How can one tell if unconsolidated and/or water-saturated sediments were intruded?

Peperites and hyaloclastites.

Peperites are rocks with brecciated textures that are the result of interaction between hot igneous material and wet or dry sedimentary material (which can include volcaniclastic sediments as well).


Image above: A peperite interbedded between Columbia River Basalt flows. Dark spots are basaltic fragments and lighter material is sandy sediment. [SOURCE FOR PEPERITE IMAGE - see more]

Hyaloclastites are formed as a result of magma intruding and/or lava flowing into ice, water, or water-saturated sediments and the subsequent formation and shattering of volcanic glass into smaller fragments.

Image above: Dark volcanic glass fragments supported in calcite matrix. Ocean Drilling Project near Hawaii observatory. [SOURCE FOR HYALOCLASTITE IMAGE - SEE FIG. 15]

|

Long time' is suggested and strongly supported by these relationships, because as I stated above, one can determine whether the rocks were 'soft' or 'hard' when intruded, when faulted, or when eroded. Additionally, the igneous rocks themselves (though not necessarily the dikes) exhibit evidence of slow cooling.

This message has been edited by roxrkool, 03-31-2005 01:05 PM


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crashfrog
Inactive Member


Message 9 of 43 (195266)
03-29-2005 5:30 PM
Reply to: Message 8 by roxrkool
03-29-2005 4:42 PM


Additionally, the igneous rocks themselves (though not necessarily the dikes) exhibit evidence of slow cooling.

Stupid question - when you say "slow", how slow do you mean?


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roxrkool
Member
Posts: 1491
From: Nevada
Joined: 03-23-2003


Message 10 of 43 (195431)
03-30-2005 12:29 PM
Reply to: Message 9 by crashfrog
03-29-2005 5:30 PM


Not a stupid question, Crash.

Slow in the sense that it can take several thousand to perhaps as much as several million years for a large intrusion to cool. I think it's entirely plausible, however, for large intrusions to cool more 'quickly' than previously thought, but even so, the time scale would still be several tens to several hundred thousand years. Mainstream geoscientists have a mountain of data to support this.

In addition to cooling rates, we also have to consider the amount of time required to emplace these large igneous bodies. Rapid emplacement (much higher pressures) affects the surrounding country much differently and would form different minerals, than gradual emplacement.

Rapid emplacement and cooling at the scale YECs require would effectively pulverize the crust and quench the magma. Quenched magma plutons would not exhibit exsolved mineral textures, would not contain large crystals, and would not result in massive hydrothermal systems like the world class deposits at Butte, MT, the Motherlode in California, or the Carline Trend, or hundreds of others scatter across the globe.

And neither would quenching result in layered intrusions (generally enriched in platinum group elements, gold, copper, nickel) such as the massive Bushveld Igneous Complex (S. Africa), Dufek Complex (Antartica), the Stillwater Complex (Montana), the Great Dyke (Zimbabwe).

Layered intrusions are the result of prolonged fractionation of a mafic/ultramafic parent magma (along with few to numerous subsequent magma injections into the same chamber) to a felsic magma. These fractionation trends and magmatic injections leave traces in the mineralogy, mineralogical textures, and geochmemistry of the complexes.

This differentiation pattern is clearly visibly in the pattern of rocks which are layered just like sedimentary rocks. The most mafic rocks occur at the bottom of the chamber, which are generally more enriched in Mg, Fe, Ca, as well as in Cu- and Ni-sulfides. With stratigraphic height, we get gabbroic rocks in the middle with felsic rocks up top.

The image below is an idealized cross-section through a layered igneous intrusion showing lithologic zones associated with mineral deposits.

This message has been edited by roxrkool, 03-31-2005 01:10 PM


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Jazzns
Member (Idle past 436 days)
Posts: 2657
From: A Better America
Joined: 07-23-2004


Message 11 of 43 (195443)
03-30-2005 1:04 PM
Reply to: Message 10 by roxrkool
03-30-2005 12:29 PM


I had totally forgotten
What a great point that I had totally fogotten about since I last had a geology course. Why are there large crystals in ANY igneous formation if the earth is less than 10000 years old? This really is a big deal because how the heck to you even begin to propose a different type of crystalization process other than cooling over long periods of time?

What a fantastic stake in the heart of YECism. Not that their are not others but this one really gets down to the basic properties of elements as we know it. I would like to see the mental contortions and complete redefinion of physics necessary for YECs to make this one fit into one of their armchair speculations.


FOX has a pretty good system they have cooked up. 10 mil people watch the show on the network, FOX. Then 5 mil, different people, tune into FOX News to get outraged by it. I just hope that those good, God fearing people at FOX continue to battle those morally bankrupt people at FOX.
-- Lewis Black, The Daily Show
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roxrkool
Member
Posts: 1491
From: Nevada
Joined: 03-23-2003


Message 12 of 43 (195506)
03-30-2005 3:56 PM
Reply to: Message 11 by Jazzns
03-30-2005 1:04 PM


Re: I had totally forgotten
For the most part, it would be safe to say igneous rocks with larger crystals likely cooled more slowly than igneous rocks with small crystals, but really, that sort of assertion needs to be backed up by other evidence as well. Many YECs like to bring up pegmatites to refute the large xls = slow cooling statement.

Pegmatite melts are exceedingly rich in incompatible elements, such as the rare earths, and they result from the residua of granitic/silicate melts. They typically contain the same mineral species as granite (e.g., K-spar, quartz), but in addition, are water-rich and gaseous. These two things directly affect crystallization rates as well as mineralogy. However, I would be hard-pressed to believe an 18 meter beryl can form in 2,000 - 3,000 years...
The Largest Crystals - American Mineralogist

This message has been edited by roxrkool, 03-30-2005 05:46 PM


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Jazzns
Member (Idle past 436 days)
Posts: 2657
From: A Better America
Joined: 07-23-2004


Message 13 of 43 (195521)
03-30-2005 4:37 PM
Reply to: Message 12 by roxrkool
03-30-2005 3:56 PM


Re: I had totally forgotten
Thanks. That is good info to know. Would hate to be confronted with the whole, "it does/doesn't work in this particular case over young/old timeframe therefore it does/doesn't work at all" argument without knowing the facts.

The gist is that you can get certain crystals from certain magmas over "decently short" periods of time but in the general case you better have lots of time or a complete rewrite of little things such as physics.

In laymens terms, does that sum it up?


FOX has a pretty good system they have cooked up. 10 mil people watch the show on the network, FOX. Then 5 mil, different people, tune into FOX News to get outraged by it. I just hope that those good, God fearing people at FOX continue to battle those morally bankrupt people at FOX.
-- Lewis Black, The Daily Show
This message is a reply to:
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roxrkool
Member
Posts: 1491
From: Nevada
Joined: 03-23-2003


Message 14 of 43 (195533)
03-30-2005 5:53 PM
Reply to: Message 13 by Jazzns
03-30-2005 4:37 PM


Re: I had totally forgotten
Yep. Under the right conditions, large crystals can form in 'short' periods of time. But like you said, any discussion of rapidly cooled granitic or gabbroic melts would require a whole lot more research and supporting evidence than "I don't see why it would take that long" or "Labs can form large crystals from silicate melts in a short time, so all melts must be able to cool rapidly and form large crystals as well."
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Nighttrain
Member (Idle past 518 days)
Posts: 1512
From: brisbane,australia
Joined: 06-08-2004


Message 15 of 43 (195540)
03-30-2005 7:55 PM
Reply to: Message 13 by Jazzns
03-30-2005 4:37 PM


Re: I had totally forgotten
Hi, Jazz, I was thinking about metamorphic rocks, esp. the formation of shale->slate->shist and I wondered if you could pin Faith,etc., to what depth they thought the Flood dumped sediments. Did it scour bedrock? Or add to existing sediments? If so, where is the dividing line? And how do they explain metamorphics on today`s surface?

edited for clarity

This message has been edited by Nighttrain, 03-30-2005 07:55 PM


This message is a reply to:
 Message 13 by Jazzns, posted 03-30-2005 4:37 PM Jazzns has not yet responded

    
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