Nicholas ([info]nwhyte) wrote,
@ 2007-10-07 08:10:00
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Entry tags:cool links

Two fascinating links
Ancestral rivers of the world

What if the Ice Ages had been less icy?

(Hat-tip to [info]tsm_in_toronto commenting in reply to [info]james_nicoll.)



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[info]communicator
2007-10-07 09:58 am UTC (link)
I love the big-time of geology; it stretches my brain like SF and cosmology do.

I love the 'creek running north' blog timeline of the grand canyon

~1,200,000,000: During the Stenian period, as the supercontinent Rodinia is assembling, a layer of dolomite sediments out atop the Vishnu schist and Zoroaster granite. This will be called the Bass Limestone. After a relatively brief period of time, perhaps only a few million years, the sea from which the Bass Limestone was deposited recedes, and river deltas along the advancing shore lay down mud, silt, and sand that will become the Hakatai shale. These wetlands are home to stromatolites, large reef-like structures made by colonial cyanobacteria. The Hakatai emerges above sea level, is eroded away in part along with any overlying layers, and then re-submerged, after which sands are deposited —these will become the Shinumo Quartzite — and then tidal flat sediments upon the sands, which become the Dox Formation

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[info]jdigital
2007-10-07 05:12 pm UTC (link)
I give it at most a week before someone puts up a competing hypothesis blaming the ancestral rivers somehow on the Great Flood.

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[info]pwilkinson
2007-10-08 07:35 pm UTC (link)
Fascinating indeed - though I notice that the first of your two links somehow misses the mechanism for getting rivers through mountain ranges featured in the second link - and the European map in the second link somehow misses out on the Goring Gap, which is a beautiful if somewhat minor example of what is being talked about.

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