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Thursday, 15 November 2012

Meltwater conduits

In the light of the comments about that snow tunnel, here are a couple of pictures of tunnels in glacier ice, for comparison.  The one above is a conduit (actually, it looks like a moulin) on a glacier in New Zealand.  Note the very strong scalloping -- indicating very turbulent meltwater flow but not, I think, a situation in which the "pipe" was completely filled with water.  In contrast, look at the one below.  This photo comes from a glacier in Peru.  It's a magnificent conduit which has clearly carried vast amounts of meltwater under very high pressure, with the tunnel filled with water for a limited period while a glacial lake was being drained catastrophically. There are signs that there might have been a sort of spiral flow.  The walls of this tunnel look VERY different...

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