Saturday, August 22, 2009

Grand Canyon's Great Unconformity

Well, I once got my hands on a newsletter from the Midwest Creation Fellowship a few years ago. 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.

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