Wednesday, November 09, 2005

Grand Canyon's Great Unconformity



Well, I've just gotten my hands on the latest newsletter from the Midwest Creation Fellowship. In it, they list the winners of their 2005 essay contest for junior and senior high school children. The winner? Beth Conway of Alliance, OH. And her essay was about, you guessed it, the Grand Canyon.

Essentially, she argues that one of the best evidences of the Genesis Flood comes from the Great Unconformity. This is a very visible line where angled sedimentary layers suddenly meet perfectly horizontal sedimentary layers. It looks almost as if someone took a kilometer-sized power sander and leveled off everything before more deposits were layed down on top. A picture of the unconformity is shown here, situated behind the portable commode we used while on the NCSE rafting trip. (This way we could contemplate the wonders of nature while, well, answering the call of nature.)

Beth Conway thinks that since the Great Unconformity was caused by the rushing waters of Noah's flood planing off rugged mountainous edges, before the currents settled down and layed down new sediments. But even the biggest amount of rushing water wouldn't level things off in such a perfect way. Waves pounding into a shallow oestuary could level off any jagged edges, but that wouldn't fit perfectly either, plus it would take millions of years, and that doesn't fit the creation model very well. What could have leveled the angled mountaintops before they were buried? What could have caused this pattern?

The best explanation seems to be that it was a glacier which did this. Only a glacier can plane off rugged, jagged mountaintops with such level precision. A massive enough glacier can literally bulldoze over rock, leveling off everything in its path. Also, the rock immediately below the unconformity dates to about 825 million years, while the rock immediately above it dates to about 570 million years, thus making a 255 million year gap in time between the two. Precisely during that gap in time, we know from other geologic evidence that the world was virtually covered in glaciers in the largest ice age the planet had ever seen. It makes perfect sense that a glacier planed off the angled, mountainous layers over 250 million years, before the earth warmed, oceans rose, and sedimentary deposits began to accumulate once again. Certainly, this makes much more sense than claiming that a global flood did it.

Eric

13 Comments:

At 10:47 AM, Anonymous Anonymous said...

Then what about the formation of the "little grand canyon" by the eruption of Mt.St. Helen in 1980 - 1981? Here we know the cause as a lot of water (liquid form) over a short amount of time. It would seam that if we didn't witness such an action in progress, then your means of explaining away the global flood mentioned in the Bible with this same reasoning. Furthermore This post touches on the formation of the canyon, but speaks nothing of the great paraconformity known by the Muav and Redwall limestones.

 
At 2:45 PM, Blogger SaganJr said...

My co-rafter, Dr. Alan Gishlick, has visited the "Little Grand Canyon" site in the St. Helens area. (I plan on visiting there myself.) He was very disappointed in the condition he found it in. The "canyon" walls have collapsed, and there is now nothing there but gentle hills. That's because this canyon wasn't carved out of rock the way the Grand Canyon was.

 
At 10:52 PM, Anonymous Anonymous said...

As far as I know, the Great Unconformity is still unexplained, so everything you mention is speculation. Aliens could have come and shaved off 500 million years of rock just to screw with us as far as you know.

I suppose you'll try to explain polonium radiohalos next. IMO, these are far more interesting. Their existence indicates that the rocks they inhabit were formed in less than a few microseconds (the half life of a form of polonium). This must be true, if radioactive dating is to be believed.

 
At 9:05 AM, Anonymous Anonymous said...

no, that doesn't make sense. there were no glaciers in the grand canyon. if you research this a little more, you'll find that a) during the most extensive ice ages, glaciers only extended as far south as Nebraska, Illinios, Wisconsin, and Kansas during the Pleistocene. b) the erosion was caused by water, though certainly not by a "great flood" that encompassed the earth. Before the deposition of the Tapeats Sandstone there was what's called an epicontinental sea (actually there were several that rose and receded over millions of years that are recorded geologically in the sedimentary layers of the grand canyon.)
so, she is wrong, but you are pretty far off target as well. no, the great unconformity is not evidence of the great flood (esp. since this part of the unconformity actually represents something more like 1.2 billion years), but it was not worn down by glaciers since those create u-shaped valleys, which the grand canyon most certainly is not and there is no other evidence of glaciers having been there.

 
At 1:43 PM, Blogger SaganJr said...

The Pliestocene? Man, that's in the Cenozoic Era, essentially near-modern times. We're talking Pre-Paleozoic, Pre-Cambrian times, here. And there is outstanding evidence for a "Snowball Earth" which glaciated much of Laurentia (which would later become the North American Continent due to plate-tectonic activity.

Yes, small alpine glaciers do form U-shaped valleys. But we're talking one hell of a glacier here! Probably one the size of 2 states. This isn't unheard of. I'm from Wisconsin, so I can see first hand how the Pliestocene glacier known as the Green Bay Lobe leveled much of the area from Waupaca to Madison to Green Bay and nearly to Milwaukee. No, the glacier idea isn't scientifically proven, but it's very plausible. I'm thinking of making it my senior thesis at the University of Wisconsin Milwaukee.

Nice to see someone's been reading this. Maybe I should start posting again.

 
At 3:16 PM, Anonymous Anonymous said...

I was looking up "The Great Unconformity", and found very little explanation. Your posts have helped to shed light on the subject.
It must have been the aliens!
Although the snowball earth is more plausible.
Thanks for the info, now I can sleep at night, instead of contemplating the causes for "The Great Unconformity".

 
At 4:21 PM, Blogger Terry said...

Some advise: for those of you who theorize on the creation of the earth, keep it theoretical because the second it becomes belief it becomes a belief system and then mere mankind is WAY out of its league for understanding the Creator's recipe for creation.

 
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At 5:11 PM, Blogger SaganJr said...

You certainly may. Thanks for asking!

 
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At 5:43 AM, Blogger SaganJr said...

I don't understand. If the link is down, how can you post a commment to it?

 
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