I see that, once again, TB has decided to enter the realm of sedimentology where he has been thoroughly trounced several times on this board. Sure doesn’t say much for his being a quick learner. I think the gist of what TB is saying is that since it is possible that sediments can be deposited rapidly, then the entire geological record should be reinterpreted to reflect a global, one year flood. He further states that the understanding of rapid sedimentation is somehow ‘new’ and was previously misunderstood by geologists. How those geologists missed storm deposits and turbidites and mass wasting deposits, is beyond me, but since TB is so certain and SO well-versed in mainstream geology, I will just accept that for now.
However, TB has touched upon one of my pet peeves of creationist ‘geology’ in pointing out that some laminations can form rapidly. This is not a great mystery. But, just how we get from laminations that can form in seconds to the Navajo Sandstone being deposited in a matter of days is quite a reach. It is as though creationists have found some minor factoid of geology that
appears to support their position, then promptly put on blinders to every other fact of geology. This is an egregious case of selective data presentation. Perhaps a few question would be in order.
1.Do any of the empirical data you are fond of quoting, suggest exactly how long the time interval is between catastrophic lamination-producing events?
2.Do they have any suggestions how long it takes to produce a set of laminae? How about a bed of laminated sands? How about an entire formation of laminated sands? If not, why not? And do you think this just
might be important?
3.Do you have any idea how to account for the rapidly produced laminations that have been formed and then destroyed by erosion? How many seconds do you think are represented by those lost laminae?
4.If we have laminated sediments forming today, under non-flood conditions, why is the presence of rapidly formed laminations considered to be evidence of a global flood? Does this really make sense to you?
You quote Blatt, Middleton and Murray as saying:
p132 "Many strata must have been deposited very rapidly. In terms of geological time, they represent essentially instantaneous events, usch as floods, that had durations ranging from a few seconds to several days."
I agree.
Many strata are deposited rapidly, but it is a logical leap to then suggest that all, or even most, layers are rapidly deposited. Do you understand that if even one formation in the thousands of meters of ‘flood sediments’ does not form rapidly, that your entire scenario of a one-year flood is gone?
So far, you have succeeded in telling us that turbidites and some sandstones are rapidly deposited. What about limestones? What about coral reefs? What about evaporates? What about chemical sediments? What about pelagic sediments? These are scattered throughout the geological record. Do you propose that we just ignor them?
You go on to quote Blatt and others:
p135 "In the past there has been a tendancy to interpret each lamina as produced by a separate sedimentation event - for example, a tidal cycle, the swash and backwash of a single wave, or a single bed load avalanche. It is now clear, however, that laminae may also be produced by strong flow, particularly during traction on a plane bed in the upper flow regime."
What do you suppose they mean by ‘a tendency? Do you realize that they are talking about short events here in both cases: an avalanche, a wave backwash, etc.? If you actually read the text you would see that they are talking about some sand deposits. They are not talking about an entire formation, system or group. This does not indicate any support for your position. You go on to quote Joplin:
"It is reasonable to postulate a very rapid rate of deposition; that is a single lamina [or layer] would probably be deposited in a period of seconds or minutes rather than in a period of hours....
Yes it is reasonable to postulate a rapid rate for [I][b]a[/i][/b] lamination. Does anyone else but you believe that it is reasonable for postulate a rapid for a series of laminated formations? There is nothing surprising in finding that some laminations form rapidly, and nothing inconsistent with an overall slow rate of deposition for the geological record. Remember, we are talking about average rates for the entire geological record.
There is factual evidence from both field observation and experiment that laminae composed of bed material are commonly deposited by current action within a period of seconds or minutes.'
Yes, commonly. However, this again refers to an individual occurrence of laminations and is not a universal statement. My impression is that usually these statements refer to sand deposits. I see nothing here that requires rapid deposition of all laminations.
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TB: There is no reason why the majority of the geological column cannot be interpreted in this way.
Wrong. According to your references, there is no reason that SOME of the geological column cannot be interpreted in this way. You are taking the specific and applying it to the general. This is a common logical fallacy among creationists. In fact, some of the geological column IS interpreted this way.
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There is a lot of sorting by grain size.
Yep, lots of it occurs in the geological column.
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Paleocurrents can be measured all throughout the geo-col.
Well, I don’t know if I’d say throughout, but certainly they are common.
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Turbidite deposits make up about half the geo-col.
I challenge this statement. I believe you have been asked to document this. Please do so. However, I still don't see the relevance.
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These things are not emphasized in 99.99% of mainstream geology.
Unadulterated, BS. In sedimentology, sorting is emphasized. You would know this if you ever took a college course. Paleocurrents are discussed commonly even in freshman classes, and some studies are referred to throughout the literature. You simply do not like the mainstream interpretation. Turbidites are practically their own chapter in even the earliest of geology courses. However, turbidites are not as common as you have been misled to believe.
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Paleocurrents do not rate a mention in the index of most university geology texts.
Well, paleocurrents are a fairly specialized sedimentology subject. I guess I wouldn’t expect much to occur in general intro textbooks.
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You get it by borrowing actual monographs on sedimentology and stratigrapy. How many of these monogpahs have you read? I've read a dozen or so from cover to cover.
Good for you. Bu this is a problem. You have not covered the basic, introductory texts. You should do that so you understand what the monographs are talking about. It is clear that you do not.
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Paleocurrents are the trade secret of geology.
Your opinion. But I suppose we had to have at least one reference to the geological conspiracy. I’m sure that after reading your posts, the universities will change their curricula for you.
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I appreciate your other evidence but the overwhelming evidence argues for rapidity (yes, with breaks in between surges).
Yes, for some units, and some very long breaks. In fact, some breaks represent periods of erosion and mountain building.
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Here's a quote I posted a while back here from last (S-hemisphere)summer's mainstream readings:
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Pettijohn, p520-521
"The stability or persistence of a particular paleocurrent system through time is indeed one of the most astonishing results of paleocurrent measurements. Cross-bedding in a 12,000 foot (3,660m) sequence in the Moine series of Scotland displays a uniformity of orientation throughout which was described by Sir Edward Bailey as 'the most surprising single phenomenon' displayed by these strata." (Wilson et al Geol Mag 90,377-387 (1953)
Astonishing, perhaps, but really only in a framework that lacks a geotectonic perspective. You will note that this was written well before plate tectonics was formulated into a viable theory. You also neglect to point out that this ‘mystery’ has an explanation. Perhaps you should have read a little further into Pettijohn...
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I do not claim that I can prove that all of the strata formed rapidly.
But you have to. If not, then there are some layers that formed slowly. Your model cannot handle this. You have only a year to complete all of your processes. This is one problem of taking an absolutist position. They are exceedingly difficult to defend.
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But there is no real reason why each bounded sequence was not rapidly formed.
Individual units, to be sure, but not the entire geological history of any area. You have presented no evidence to support this.
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I do not quote them out of context. these mainstream researchers are poiinting out that what was once thought was eons is, in some cases, rapid. We of course wonder why not all continuous sequences?
But you are implying that they might think the entire geological column was laid down rapidly. Their work does not support your scenario.
Now, since you have quoted Blatt, and others, I thought I might just check and see how many entries there are for 'paleocurrents'. Hmm, it looks like there are about 15 pages with reference to 'paleocurrents.' Not really much of a secret is it?
Moving on, the text says:
"On the largest scale, mapping of directional sedimentary structures in many rock units has revealed that despite much local variability the average paleocurrent directions remain almost constant over very large areas and persist with only slight changes through long periods of geological time. This observation has given rise to the concept that the basic regional control of paleocurrents was the paleoslope."
Now, why do you find Blatt and others so authoritative on rapid depostion but ignore what they say about paleoslopes? I can see why you might not want to present us with this quotation.
Moving on, we find that
"The (rapidly deposited) bed may, of course, represent the final stage of a long period of reworking"
And:
Probably most beds are removed by erosion before they can be buried and thus preserved in the geological record.
And:
"The importance of the unusual event can, however, be overstressed. For example, spectacular changes in beaches may be produced by a few days of violent storms but profiling frequently reveals that many of the storm deposits are reworked by wave action during the much longer periods of calm weather."
Now, just what is this business about 'much longer periods of calm weather?' And what about eroded beds? And 'long periods of reworking?' Is there some reason that these facts are missing from your selection of quotes from a mainstream geology text?
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