Unconformities and the age of the Earth: Challenge to Anti-Climacus and other YECs

They certainly are. I have got to say this is a thread that deserves a POTM. Now if only I can get it proposed before the Queen beats me to it?

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Aslan is not a Tame Lion

A bit of a minor correction for the very first post of this thread. The Great Unconformity of the Grand Canyon is not always an angular unconformity. When the tilted layers run out, it is directly on the Vishnu Schist bedrock and thus becomes a nonconformity. In other words when horizontal Tapeats Sandstone is directly on top of the tilted strata of the Grand Canyon Supergroup, it is an angular unconformity and then it is directly on top of the Vishnu Schist which is not layered rock, it is a nonconformity. It is the same unconformity since it is one erosional surface, what changes is what is the rocks below that surface.The Great Unconformity is not only exposed at the Grand Canyon, it is also exposed near Los Vegas at a place Frenchman Mountain. Thus one can visit the unconformity without going deep into the canyon. I recommend taking a look at the Frenchman Mountain Great Unconformity site which is rather nice. The last page of the site has an interesting image (which I shrink here):I think we can add a few more steps in the formation of the geology in the area! I know this is pushing topic: someone might want to start a thread on faults. But this is where the subject of faults and unconformities overlap a bit since both are involved.Until tomorrow when I plan to boldly take this thread quite a bit farther from home with an angular unconformity that is out of this world.This message has been edited by Harlequin, 01-11-2005 15:38 AM

I agree with Jar and Asgara, great posts. Thanks!Those sorts of decollements are found all over the Basin and Range Province. The Snake Range in Nevada is another one. Also, I believe decollements are also responsible for metamorphic core complexes. But yes, that's a whole other thread.

Today I have an angular unconformity that different from what I have presented before in this thread. The left image shows an angular unconformity on ice. (The right image is something else and would be a subject of another thread.) So basically we have layers of ice instead of strata or volcanic material which the previously discussed unconformities in this thread. The image was taken by an orbiting satellite.Source: Mars Global Surveyor: Unconformities and Deformation in the North Polar Layered DepositsAnd I bet people did not take my comment that I was going to present an out-of-this-world image of an angular unconformity literally...There are angular unconformities in rock on Mars as well. The next image came from Spirit which is exploring the Columbia Hills in Gusev Crater on Mars:


Source and larger images: Press Release Images: 04-Nov-2004: Spirit Adds Clues About History of Rocks in Martian HillsScientists would have liked to have taken a closer look, but the target was poorly placed since it would have required being on a hill which would tilted the solar panels away from the Sun which is a serious problem during the Martian winter.This message has been edited by Harlequin, 01-11-2005 18:37 AM