Monday, February 20, 2017
Glacier Terminology
Before we delve into Alaska's Flora and Fauna...I found this fascinating.
It seems Alaska's Rivers of Ice have a language (terminology) all their own.
Who knew, right?
Arete: Sharp narrow ridges formed on a mountain by a glacier.
Bergschrund: The crevasse that separates the stagnant headwall ice from the flowing ice of the glacier.
Calving: When an iceberg breaks away from the glacier.
Crevasse: An open crack in the glacier's surface.
Erratic: A boulder swept down a glacier and deposited elsewhere. Some erratics can weigh tons.
Firn or Neve: The area of a glacier covered with snow throughout the entire year.
Ice Fall: The Jumbled and broken ice which occurs when the glacier flows over a steep drop-off.
Kettle: A huge block of ice left behind as a glacier receded. Filling an area with water it sometimes becomes a lake. Mirror Lake in Alaska is what remains of an enormous Kettle.
Mirror Lake
and an example of a smaller Kettle.
Nunatak: Mountain tops or ridges poking through the glacier and forming small islands.
Seracs: jutting blocks of ice from the surface of the glacier...sometimes hundreds of feet tall.
The areas between the seracs are also crevasses.
Outburst Flood or Joklhlaup: A tremendous release or flood of water that was trapped beneath or behind a glacier.
Glacial Flour and Glacial Silt: The finely ground rock that is left behind where a glacier has passed over an area.
Glacial Flour
The coloration of this lake due to Glacial Silt.
Ice Geyster or Bubbling Pond: Glacial meltwater that comes up through the surface of the glacier. Usually liquid. Some refreezes like this example.
Ice Quake: The sound of muted thunder. Sounds like it is miles away. Ice shifting and grumbling within the glacier itself.
https://youtu.be/-1cciMTWKHA
The Sounds of an Ice Quake.
(yeah...my ass would be outta there)
And another Interesting Ice Sound
https://youtu.be/b6AZZtpJc7M
Ice Sizzle: As an iceberg melts there is a sizzling or popping sound like Rice Krispies. This is caused by the release of the trapped gasses inside.
Example
https://youtu.be/Ny2LBXWs_P0
Ice Worm: 3 mm long and brownish-black. These are the only worms known to inhabit ice. They feed off the red algae that grows on glaciers.
Moulin (or Glacial Mill): Channels of water that plunge through channels and down holes deep into the middle of the glacial ice. Known for their sound.
Example
https://youtu.be/isqqFlt4Lvc
Glacial slide: A short period when meltwater causes a glaicer to move 100x faster than it normally would. Results in Calving at the edge.
Example with Sound
https://youtu.be/ElvSYfGMGvM
Sun Cup: The short textured cupping on the surface of the glacial from sun and wind erosion.
Sun Cups.
A nice side adventure...and proof that you can learn something new every day!
More Anon...