Nick Barnes said he found the GC disappointing after Utah. So did I the first time I saw it, in ~1978, so I'd warned James that it wasn't really up to much. Naturally with such low expectations, he was delighted and thought it was thoroughly grand. I enjoyed it more this time too, as I made the effort to appreciate the geology. The Colorado plateau rose up, and the Colorado river cut down (although quite how it did it on such a grand scale is not at all clear). In only 6 million years the river cut through layers of rock going back half the age of the earth. Wow! And here are all the layers. What a lot of different colours! The tilted red rocks near the river are special - they are the Grand Canyon Supergroup, and are not visible in very many places.
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Posted By jules to jules' pics at 7/01/2011 01:48:00 PM
3 comments:
The depositional age of the Grand Canyon Supergroup is one of geochronology's more embarrasing mysteries.
Tourist says: gosh, how old are those tiled rocks.
It turns out there's about 300 million years years of wiggle room for the neoproterozoic part, unless you're willing to hang your hat on some very tenuous data- people look for things like 2% abundance detrital populations.
James and/or Jules, are either of you taking a punt on the sea ice extent this year?
Well that's better dated than most of the paleodata we use in climate modelling :-)
Done the sea ice now.
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