From: Joel Moore (jxm957@psu.edu)
Date: Tue Apr 08 2003 - 21:54:33 EDT
See my responses below.
>Hi Joel,
>
>On Wed, 2 Apr 2003 10:12:22 -0500 Joel Moore
><<mailto:jxm957@psu.edu>jxm957@psu.edu> writes:
>
>1) The Muav and Redwall limestones are not in direct contact in many
>or most parts of the Grand Canyon. In the eastern part of the
>canyon, the sequence (from oldest to youngest) is the Cambrian Muav
>limestone, Devonian Temple Butte limestone, and the Mississippian
>Redwall limestone.
>
>That being the case, then the paraconformity (time gap) isn't as
>large as I'd thought. In the eastern part of the canyon the entire
>Ordovician and Silurian are missing, which is only 100 million
>years.
>
>For the western canyon, the sequence (from oldest to youngest) is
>the Cambrian Muav limestone, unclassified dolomites, Devonian Temple
>Butte Formation, and the Mississippian Redwall limestone.
>
>Here again, the Ordovician and Silurian are missing. The only thing
>the Devonian Temple Butte does, where it exists, is reduce the time
>gap by about 1/3 - assuming that the Temple Butte represents the
>entire Devonian of 50 million years.
>
>2) In the places where the Redwall is in contact with the Muav, the
>Redwall fills in surfaces that have been eroded through the Temple
>Butte and into part of the Muav limestone.
>
>First of all, you're assuming that the Temple Butte was actually
>deposited in the areas where it is now missing. I understand the
>correlation you're making of the Temple Butte from west to east, but
>working with a bunch of engineers as I do, we are careful to
>separate hard data from inference. It doesn't affect much in the
>world of academia, but for consultants there is a huge liability
>issue there.
>
>Second, whether the Temple Butte was ever continuous or not, what
>you've presented above is not inconsistent with a short timeframe of
>deposition. Given that the Ordovician and Silurian are missing,
>there is a 100-million-year time gap on top of the Muav, yet only
>limited erosion into the Muav. Steve Austin, in his book _Grand
>Canyon_ (1994), says "about 30 feet of channeling of Muav can be
>seen in excellent expoures in Marble Canyon, but this disconformity
>has been interpreted to include erosion of the Ordovician and
>Silurian Systems supposedly accumulated and eroded over a period of
>100 million years!" (p 70) Thirty feet of channeling is nothing on
>a surface above which two entire systems were eroded (if they were
>ever deposited in the first place). The weight of these
>observations favors a short timeframe.
>
RESPONSE
The Temple Butte was there in places where channels because there is
clear physical evidence for erosion. I don't think any geologist
would say that "the Ordovician and Silurian Systems" had been
deposited. First of all, Ordovician and Silurian are time periods,
not systems. The names refer to type-localities that were established
by 19th century geologists, many of whom were evangelical Christians.
Also, the conclusion that these observations favor a short time frame
does not follow from the few observations mentioned above. The
deposition of marine limestones occurs in a fairly narrow range of
environmental conditions, which do not seem likely to be present in
the event of the Flood.
Because I'm feeling frisky, I'll say something about engineers. Hard
data is a rather loaded term. It implies that one has the complete
picture from the "objective" facts and everything outsides that is
subjective. Any "real" data set (i.e., that is outside of laboratory
and controlled conditions) is incomplete and so the investigator must
make educated guesses or inferences about things (historians operate
a similar way). Those educated guesses can be more or less correct,
though the rightness of the guess may not be verified until years
later. For example, one geologist postulated in the 1920s that the
Scablands of eastern Washington were caused by a large flood. His
fellow geologists thought he was crazy until another geologist
presented evidence for Glacial Lake Missoula.
>3) It's important to remember that the Muav limestone was not
>deposited at the same time over the whole extent of the formation
>(i.e., a cake-layer model is not correct). The lower Muav limestone
>is the same age in the western part of the canyon as the Tapeats
>sandstone (an older Cambrian sandstone) is in the eastern part of
>the formation.
>
>
>Agreed. Austin diagrams this facies relationship in his GC book on page 69.
>
>Thus there are several millions years difference between the age of
>the bottom of the Muav limestone in the eastern and western parts of
>the canyon because the sediments are part of a trangressive sequence
>
>Your "several millions years" is inference, based upon something
>besides "because the sediments are part of a trangressive sequence."
>Transgression can happen slowly or quickly and there is certainly
>little limit on the speed of deposition of sandstone and shale.
>Lime mud may take a little longer, but not 'millions of years.'
RESPONSE
Do you have any evidence or time frame for what is "slow" or "quick?"
Don't forget that "quick" in geologic time is just about anything
below 50,000 years for the Phanerozoic.
>
>Another thing to keep in mind about paraconformities is that they're
>viewed with skepticism by some in the geologic community. Also from
>my textbook, "Some authors doubt the need for the paraconformity
>category, arguing that most reputed paraconformities, if traced
>laterally, eventually exhibit some physical evidence of erosion and
>thus prove actually to be disconformities (Davis, 1983)."
>
>To turn the argument of Davis, 1983 (can you give the rest of the
>reference?) around, we could also say that disconformities, if
>traced laterally, eventually exhibit some lack of physical evidence
>of erosion and thus prove actually to be paraconformities. I agree
>with Darryl here, who said (post 2 Apr 2003): "Ok, I will admit some
>things are indeterminant at a particular point and you have to look
>around a bit. Maybe the geologists who hold this view are saying you
>should follow it a few feet instead of the miles or so that I
>immediately thought of when I read the comment." Davis is simply
>toying with sematics in order to avoid the issue.
>
>My sense is that the number of people who are in favor of the
>paraconformity category has been declining over the last couple of
>decades.
>
>This sounds like the reason is because the concept of
>paraconformities is inconsistent with millions of years. As I said
>before, one or the other has to go; the two are mutually exculsive.
>
>Regarding sheet flow erosion, I can't claim any strength in physics,
>but my understanding of fluid flow is that flowing water cuts
>channels. Sheet flow is definitely the exception rather than the
>rule.
>
>Noah's Flood was the exception rather than the rule. We do see
>those nice flat plateaus above the GC. Austin comments: "However,
>the King James II Version of [Genesis] 8:3a, 5a, is: 'And the waters
>retreated from the earth, going and retreating,...And the waters wre
>going and falling until the tenth month.' The phrase 'going and
>retreating' involves a Hebrew construction similar to that of the
>raven's motion (8:7), indicating that the waters were rushing back
>and forth with an action resembling tidal movement, as the overall
>level of water progressively declined." (p 77) "The present erosion
>surface [plateau] on top of the Kaibab Limestone, whiach forms many
>of the plateaus in the Grand Canyon area, was caused by sheet-flood
>erosion, as northern Arizona became exposed later in the Flood." (p
>78)
RESPONSE
What might have caused the waters to slosh or rush back and forth like tides?
>
>If I remember correctly, I've seen channelized flow in some wave
>wash on beaches in Cape Cod (so low slopes and small water supply).
>The more water you have and the faster the water is flowing, the
>more likely the water is to channelize.
>
>I would think if you have a flooded condition and moving water,
>especially on relatively plane, sloping land, it could not
>channelize. I agree that with your "small water supply" we would
>see channeling, but on the beaches I've seen, such as the Carolina
>and Gulf coasts, waves retreat in sheet flow.
>
>Bill
RESPONSE
Flood geology needs to have a coherent model (one that is physically
possible - thus runaway plate tectonics does not count). Though not
likely in my estimation, flood geology may have some explanatory
power for a single outcrop or region but it completely falls apart
when it is applied to the global scale. Appealing to the small scale
really doesn't work.
I won't be able to respond to any future emails on this topic for a
while because I have too much to do with end of the semester work and
upcoming field work.
Joel
-- Joel Moore 315 Hosler Department of Geosciences Pennsylvania State University University Park, PA 16802(814) 863-8055
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