From: Don Winterstein (dfwinterstein@msn.com)
Date: Wed Mar 26 2003 - 05:44:50 EST
David Campbell wrote with respect to plate tectonic spreading zones:
> The rigidity of the upwelling rock is not especially important.
Perhaps; and I acknowledge that the model in my head was a
bit fuzzy as I wrote. But if the upwelling rock were much hotter (well beyond the melting point) than usual and thus
under correspondingly higher pressure than usual, at some point the liquid
rock would break through the rigid rock surface, spew out as a volcano and reduce
any horizontal force from the fluid pressure--similar to what would happen to the pressure at
the walls of a boiler if you poked a hole in one end. In other words, if
rock rigidity all the way to the surface went to zero, horizontal force on
the plates from the liquid rock would be reduced.
What I don't know, and maybe you do, is what fraction of the total horizontal force on the plates comes from pressure generated by upwelling rock. Perhaps it's negligible to begin with, or perhaps no one knows: You can deal with this kind of thing only through modeling, not measuring.
[Actually, I'm mildly embarrassed about that post. It was a first draft kind
of thing where you let your feelings hang out, and I was going to clean it up later when my head had reasserted itself. Instead, I apparently pushed "send" instead of "save."]
> There is the irony that the second law of thermodynamics is routinely
>wrongly invoked against evolution, when in fact it is a major obstacle to a
>global flood and catastrophic plate tectonics. Additional energy to speed
>up the process requires the production of lots of extra heat.
Points well taken. However, if you're in the ad hoc ballgame, as Creation
Research people seem to be, it seems you can almost always get a desired result. What if God had laced the asthenosphere and upper mantle with lots of radioactive isotopes that just happened to build up their heating effect to a maximum about the time of the Flood, triggering instability?
But I don't see how YECs can in any way explain the Devonian reefs in Alberta in a young-Earth frame. It's not that those reefs are really so special. Oil company geophysicists and geologists around the world have thousands of similar examples of sedimentary columns that equally defy a young-Earth explanation. No doubt that's why the few YECs I knew in the industry before long became either OECs or A/As (Atheists/Agnostics). It's just that the Devonian reefs of Alberta make the case so clearly and compellingly.
For anyone who may be interested, I recently composed the following notes on those reefs (from memory, so an occasional detail or two may not be strictly accurate):
I worked two years in Alberta for an oil company. I worked on the Devonian reefs myself and had lengthy discussions of the reefs with people who'd spent their entire careers on them. The experts indicated the reefs were essentially perfectly preserved specimens, apart from, of course, the diagenesis that had occurred since burial. These reefs are the primary source of Alberta's oil and thus have been studied in excruciating detail for many decades. Thousands of wells penetrate the reefs, and there are very large numbers of core samples of fore reef, back reef and reef rim facies stored in Calgary in government facilities. The Canadian government requires all cores to be turned over to a central facility, so they're open to the public for study. I've seen lots of fossils in the cores myself.
Reefs have very peculiar features, including consistent patterns in the kinds of marine life supported in various parts of the reef. Geologists study both modern and ancient reefs to learn what these are. Reefs are laid out in ways unlike any other sedimentary feature, and especially when they cover hundreds of square kilometers, as they do in Alberta, an educated geologist with lots of core samples absolutely would not confuse them with anything else. The pattern of fore reef, reef rim and back reef repeats world-wide in both modern and ancient reefs. The reefs themselves as well as their whole, well-known extensive environment embody the very epitome of stability and the very antithesis of cataclysm, either global or local. By studying the cores and the seismic data geologists can monitor how the reefs grew and evolved over long periods of time.
Reefs grow in shallow, warm seas. Because of their need for water of a certain depth, in relatively flat-lying areas they therefore usually form at a relatively consistent distance from shore. From maps of the reefs in Alberta and other places where reefs are extensive, geologists usually can figure out pretty well where the ancient shorelines were, and where the water got deeper. A typical plan view of a reef would show a long, serpentine structure. In the case of the Swan Hills reef in Alberta (if I remember correctly), the structure curves back on itself, indicating it grew in a very large bay. A recent target for oil companies has been "pinnacle" reefs: small reefs separated from the main reef complexes. The belief is that such reefs got their start in deeper water on sea-floor mounds that provided a suitable environment. Basically, geoscientists have every reason to believe all these reef structures grew in place as we find them today.
From cores, well logs and reflection seismic data we know the geologic structures around the Alberta reefs extremely well. These sedimentary rocks today are as flat-lying and featureless as any you'll find anywhere, indicative of an absence of major tectonic activity since burial. The seismic expression of the reefs--often barely detectable by eye--is typically the only structural feature evident in the area. The overall picture is one that strongly supports the idea of very slow, uniform burial to depths that are now (if memory serves) around 12000 ft.
If anyone can explain these in a young-Earth framework, I'd like to hear it.
Don
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