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Medial Moraine and Deformation Crevasses


Medial Moraine and Deformation Crevasses
Photo Information
Copyright: James Parker (Jamesp) Gold Star Critiquer/Gold Note Writer [C: 1252 W: 0 N: 4842] (14380)
Genre: Landscapes
Medium: Color
Date Taken: 1994-08
Categories: Mountain
Photo Version: Original Version
Date Submitted: 2007-11-06 23:26
Viewed: 593
Points: 32
[Note Guidelines] Photographer's Note
I took this shot on the Canadian - US border. To get there I drove my hire car - a Thunderbird - up miles of dirt track (well I did wash it before I returned it ;) ).

This is scanned slide taken with a Pentax Z1.

The shot shows medial moraines and deformation crevasses quite well.

Moraine refers to any glacially formed accumulation of unconsolidated debris which can occur in currently glaciated and formerly glaciated regions, such as those areas acted upon by a past ice age. This debris may have been plucked off the valley floor as a glacier advanced or fallen off the valley walls as a result of frost wedging. Moraines may be composed of silt like glacial flour to large boulders. The debris is typically angular. Moraines may be on the glacier’s surface or deposited as piles or sheets of debris where the glacier has melted. Moraines may also occur when glacier or iceberg transported rocks fall into the sea as the ice melts.

LATERAL MORAINES are parallel ridges of till deposited along the sides of an alpine glacier 9can be seen here but not as obvious as the medial moraines). The unconsolidated debris is deposited on top of the glacier by frost shattering of the valley walls and from tributary streams flowing into the valley. The till is carried along the glacial margin until the glacier melts. Because lateral moraines are deposited on top of the glacier, they do not experience the postglacial erosion of the valley floor and therefore, as the glacier melts, lateral moraines are usually preserved as high ridges. Lateral moraines stand high because they protect the ice under them from the elements, which causes it to melt or sublime less than the uncovered parts of the glacier. Multiple lateral moraines may develop as the glacier advances and retreats.

MEDIAL MORAINES - when two glaciers meet, their lateral moraines merge forming medial moraines - here the glacier has been joined by two smaller tributary glaciers - it has two medial moraines.

DEFORMATION CREVASSES - The lower layers of glacial ice flow and deform plastically under the pressure, allowing the glacier as a whole to move slowly like a viscous fluid. Glaciers usually flow downslope, although they do not need a surface slope to flow, as they can be driven by the continuing accumulation of new snow at their source, creating thicker ice and a surface slope. The upper layers of glaciers are more brittle, and often form deep cracks known as crevasses or bergschrunds as they move. This is especially evident when they go round sharp corners (here) or over a steep change of slope.

Crevasses form due to internal differences in glacier velocity between two quasi-rigid parts above the deeper more plastic substrate far below. As the parts move at different speeds and directions, shear forces cause the two sections to break apart opening the crack of a crevasse all along the disconnecting faces. Projected in effect over three dimensions, one may settle and tip, the other upthrust or twist, or all such combinations due to the effects of each floating on the plastic layers below and any contact with rock and such. Hence the distance between the two separated parts while touching and rubbing deep down, frequently widens significantly towards the surface layers, many times creating a wide chasm.
Bufo, ramthakur, uleko, gracious, Alex99, earthtraveler, angybone, hester, anel, oscarromulus, Adanac, XOTAELE has marked this note useful
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Critiques [Translate]

  • Great 
  • Bufo Gold Star Critiquer/Gold Star Workshop Editor/Gold Note Writer [C: 422 W: 71 N: 984] (4241)
  • [2007-11-07 0:12]

Hello James,
it must have been a long stay claening your rental car :-)
I am a great of these type of landscapes. Glaciers are impressive from when seen nearby but also from a distance. You can really see the huge size of them.
A fine composition. THe quality of the picture didn't really suffer from scanning the slide.

Greets, Jacob

  • Great 
  • jesst Gold Star Critiquer/Gold Note Writer [C: 361 W: 0 N: 164] (2200)
  • [2007-11-07 0:38]

Nice shot. The eyes go along the road and beyond. Composition is good, nice color and detail.

Hello James,
Amazing lines in the composition!
Good point of view resulting in a well composed frame, impressive colours and details in this "aging" image!
Greetings,
Pablo -

  • Great 
  • PaulH Gold Star Critiquer/Silver Workshop Editor/Gold Note Writer [C: 1033 W: 26 N: 2998] (10820)
  • [2007-11-07 3:07]

Hi James,
amazing to see this kind of landscape, love it. The power of nature at it's biggest, and slowest. Good exposure and a great POV, i wonder how much it's retreated in 13 years...
Paul

Wow, looks like a highway made from ice, James!
The scanned slide is sharp and crisp even though 13 years old.
The shadows and contrasts make it a great mountain shot.
Thanks for sharing it and best regards.
Ram

  • Great 
  • uleko Gold Star Critiquer/Gold Star Workshop Editor/Gold Note Writer [C: 2468 W: 168 N: 7464] (23588)
  • [2007-11-07 5:58]

Hello James,
It's a pity it's so hard to get to these places as they're so fascinating and beautiful. Excellent composition, very sharp details in beautiful light. Interesting note too.
Many thanks, Ulla

Hello James,
Thank you for your effort in sharing this wonderful landscape with us!
good pov with perfect sharpness, vivid colour and so much details in Moraine!
quality composition with a most useful notes
TFS
all the best
Tony

  • Great 
  • Alex99 Gold Star Critiquer/Gold Star Workshop Editor/Gold Note Writer [C: 3043 W: 148 N: 4547] (14679)
  • [2007-11-07 8:48]

Hi James.
I like your choice for of shooting subject and superb POV and framing. Very impressive curve of road, terrific combination f lights and shadows, perfect colours and sharpness of the entire image. My compliments and TFS.
Alexei.

Hi James,
Wonderful composition of this glacier and mountains
good focus details and POV
interesting how there are dark bands on each side of glacier
TFS
Richard

  •      
  • Evelynn Gold Star Critiquer/Gold Star Workshop Editor/Gold Note Writer [C: 1978 W: 690 N: 2807] (12531)
  • [2007-11-08 0:08]

We have been to Hyder several times and often wondered just what was up that road. I had no idea one could drive that high. We had only our camper... not good for that road. This looks like a classic glacier. I wonder just how much of it is left today. I remember when that glacier on the way into Stewart hung over the road. Now it has receded far back on the other side.

TFS
Evelynn : )

Wonderful composition. What a beautiful place. Love the contrasts and shadows. Very pleasing and interesting.

  • Great 
  • hester Gold Star Critiquer/Silver Workshop Editor/Gold Note Writer [C: 1471 W: 18 N: 2981] (10944)
  • [2007-11-10 9:09]

Hi James

This is stunning. I love that sweep of ice. Perfect exposure and a stunning composition

TFS

Karan

  • Great 
  • anel Gold Star Critiquer/Gold Note Writer [C: 1174 W: 0 N: 1980] (8393)
  • [2007-11-11 8:47]

hello James,
Very interesting image. I have seen that you have taken it in 1994. I wonder how it would look today. In my countries almost every glacier lost 1oo of meters since the ninties.Excellent, very didactic note.
Thanks also for your hello from California. I hope you enjoy your stay.
best regards
Anne

James,
What an education AGAIN.
When I first "saw" this image I wondered what it was.
After reading your notes I learnt. THANKS A LOT MY FRIEND.
A lovely composition, indeed.
Greetings from Calgary.
Mario.
P.S. Please correct this:"...deposited along the sides of an alpine glacier 9can be seen..." Delete 9 and replace with "("

  • Great 
  • arfer Gold Star Critiquer [C: 2731 W: 0 N: 0] (0)
  • [2007-11-11 19:12]

Hello James

A wonderful shot of this wilderness area of the continent.
The lighting is favourable and producing some nice colours.
Well focused with sharp details.
Glad you decided to take a few shots while you were there.
TFS

Rob

  • Great 
  • Adanac Gold Star Critiquer/Gold Note Writer [C: 1049 W: 1 N: 4160] (13980)
  • [2007-11-13 20:49]

Hello James,
A nice shot of the Salmon Glacier, The drive up to here is very scenic and the view of the glacier very awe inspiring. Your capture and note are both excellemt James.
Rick

Excelente imagen.
Se aprecia muy claramente como la tierra se pliega ante el impulso del glaciar, que poco a poco la constriñe..
Saludos y tfs, JL.

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