Freitag, 4. September 2009

Geologists Who Say "Nye"

Roches moutonnées of the last glacial maximum seen by the "Geotope Fischbach" (Bavaria) with Nye channels (after a British physicist) - subglacial channels eroded by meltwater under high pressure in the limestone formation of the "Wettersteinkalk".


In warm-based glaciers, also called temperate glaciers - with the bottom near or slightly above the freezing temperature, water flows in or on the bottom of the glacier forming subglacial streams in channels, that finally join at the snout, forming a glacier outlet.

There are three types of subglacial channels, depending on such factors like glacier movement, bedrock topography and lithology:

N-channel or Nye-channel: incised in the underlying bedrock.

R-channel or Röthlisberger-channel: incised in the ice (and so not found in "fossil" form).

C-channel or Clarke-channel: partly incised in the bedrock and ice, a combination of the formerly mentioned types.

Kommentare:

Lockwood hat gesagt…

I had never heard of this phenomenon before... That's cool.

Silver Fox hat gesagt…

Very neat, and I hadn't heard of Nye channels before, either.

David Bressan hat gesagt…

I updated the post with a short explanation of the three types of subglacial channels.

Most time even in glacier textbooks these channels were only mentioned - I think they are not well studied because difficult to reach, to enter directly is impossible or dangerous - when they are filled by water.

Some researches tried to explore the channels by cameras, but is a very tough environment for the sensible technology.