GeoLog

glacier

Imaggeo on Mondays: Trapped air

Can you imagine walking into the depths of an icy, white, long and cavernous channel within a thick glacier? That is exactly what Kay Helfricht did in 2012 to obtain this week’s Imaggeo on Mondays photograph.

Tellbreen Glacier is a small glacier (3.5Km long) in the vicinity of the Longyearbyen valley in the Svalbard region of Norway. Despite its limited size, it is an important glacier. One of the key parameters scientist use to understand how glaciers are affect by a warming climate is how the melt water is transported through to the front of the glacier. The majority of models utilise data from temperate or polythermal glaciers, i.e., glaciers which have free water within the icy matrix. Tellbreen is a cold glacier, meaning the basal layers of ice are frozen to the glacier bed; despite the traditional view that cold glaciers are not able to store, transport and release water, Baelun and Benn, 2011 found Tellbreen does this year round.

Trapped air. (Credit: Kay Helfricht via imaggeo.egu.eu)

Trapped air. (Credit: Kay Helfricht via imaggeo.egu.eu)

Kay visited Tellbreen whilst at the Artic Glaciology course at the University Centre in Svalbard. ‘Each weak one excursion led us to glaciers in the vicinity of Longyearbyen’ says Kay, ‘this day we visited the glacier Tellbreen. Near the tongue of the glacier the outlet of an englacial channel enabled us to explore the inside of the glacier. We went for some tens of meters into the channel.’

What the group found were that the walls of ice either side of the channel contained impurities, from stones to gravel, as well as mud and also water. The image above shows ‘air trapped in the ice-walls of the conduit at a time when the conduit would have been filled with meltwater of the glacier’ explains Kay. Air accumulated in bubbles at the roof of the conduit. When the water in the conduit started to refreeze along the side-walls, these smooth lenticular bubbles were trapped and stored in the ice. Studying the bubbles and other impurities in the ice can give hints on the history of the glaciers ice flow and its thermal regime over several decades.

References

Baelum. K., Benn. D.I.: Thermal structure and drainage system of a small valley glacier (Tellbreen, Svalbard), investigated by ground penetrating radar, The Cyosphere, 5, 139-149, 2011

Naegeli. K., Lovell. H., Zemp. M., Benn, I. The hydrological system of Tellbreen, a cold-based valley glacier on Svalbard, investigated by using a systematic glacio-speleologicalapproach, Geophysical Research Abstracts, 16, EGU2014-6149, 2014 (conference abstract)

 

Imaggeo is the EGU’s open access geosciences image repository. Photos uploaded to Imaggeo can be used by scientists, the press and the public provided the original author is credited. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. You can submit your photos here.

Imaggeo on Mondays: Beneath a star-studded sky

Marco Matteucci captured this image of the night sky on the slopes of Mount Rosa, the second tallest peak in Alps. Mount Rosa straddles the border between southern Switzerland and Italy the pink mountain’s name comes from the Franco-Provençal word rouése, meaning glacier. Much off the Swiss side of the mountain is enveloped in the ice of Gorner Glacier, the second largest glacier in the Alps. On the Italian side, lies Belvedere Glacier, which is fed by the snow that falls on Mount Rosa.

Mount Rosa ridge, Valle d'Aosta, Italy. (Credit: Marco Matteucci via imaggeo.egu.eu)

Mount Rosa ridge, Valle d’Aosta, Italy. (Credit: Marco Matteucci via imaggeo.egu.eu)

Wish you could capture images like this yourself? You can! Take a look at this brief guide to space photography for some hints and tips. 

Imaggeo is the EGU’s open access geosciences image repository. Photos uploaded to Imaggeo can be used by scientists, the press and the public provided the original author is credited. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. You can submit your photos here.

Imaggeo on Mondays: Moulding Malaspina’s moraines

There are many different types of glaciers, each defined by where they’re located and how they terminate. Piedmont glaciers are those that flow out from a confining valley and spill out into the open, forming wide lobes. This one is Malaspina Glacier, which spreads out over the Seward Ice Field.

“Mt St Elias and Malaspina” by Jean-Daniel Champagnac, distributed by the EGU under a Creative Commons licence.

“Mt St Elias and Malaspina” by Jean-Daniel Champagnac, distributed by the EGU under a Creative Commons licence.

Stretching 45 kilometres over the lowlands towards the sea, and spanning some 65 kilometres across, Malaspina is the world’s largest piedmont glacier and the classic example of its kind. Here’s how it would look face on:

Malaspina Glacier is created by the junction of several powerful glaciers from the North including Agassiz Glacier (left) and Seward Glacier (right). (Credit: SRTM Team NASA/JPL/NIMA)

Malaspina Glacier is created by the junction of several powerful glaciers from the North including Agassiz Glacier (left) and Seward Glacier (right). (Credit: SRTM Team NASA/JPL/NIMA)

Ahead of the glacier are a number of folded moraines. Moraines are piles of unconsolidated sediment and rocky debris that have been eroded from the glacier valley walls and deposited by the glacier. Malaspina’s moraines have been folded by the force of ice pressing in from behind.

The striations in Champagnac’s photo are the remnants of glacier moraines. A number of tributary glaciers coalesce to form Malaspina, and as they enter the flow of this glacier, their debris is folded into the moving mass of ice. As this glacier flows, the debris flows with it, producing the striking striations on the glacier surface.

References:

National Snow and Ice Data Center (NSIDC): What types of glaciers are there?, accessed December 2013

NASA Earth Observatory, accessed December 2013

The EGU’s open access geoscience image repository has a new and improved home at http://imaggeo.egu.eu! We’ve redesigned the website to give the database a more modern, image-based layout and have implemented a fully responsive page design. This means the new website adapts to the visitor’s screen size and looks good whether you’re using a smartphone, tablet or laptop.

Photos uploaded to Imaggeo are licensed under Creative Commons, meaning they can be used by scientists, the public, and even the press, provided the original author is credited. Further, you can now choose how you would like to licence your work. Users can also connect to Imaggeo through their social media accounts too! Find out more about the relaunch on the EGU website. 

Imaggeo on Mondays: Carving polar canyons

This week Ian Joughin, a research scientist from the Polar Science Center at the University of Washington, takes us on the polar express to put glacial processes into perspective and find out what makes a moulin…

“Water filled canyon” by Ian Joughin, distributed by the EGU under a Creative Commons licence.

“Water filled canyon” by Ian Joughin, distributed by the EGU under a Creative Commons licence.

This canyon formed when a melt lake on the surface of the Greenland Ice Sheet overflowed and created a stream that extended out toward a crevasse field. This outflow stream filled a crevasse, causing it to fracture under the pressure of the liquid, creating a hydrofracture that ran through the full thickness of the ice sheet. This fracture created a conduit to the base of the ice sheet, known as a moulin, through which the surface water drained to the bed.

Surface water entering a moulin on Athabasca Glacier (a much smaller Moulin than the one what would have drained the Greenland lake). (Credit: Wikimedia Commons user China Crisis)

Surface water entering a moulin on Athabasca Glacier. (Credit: Wikimedia Commons user China Crisis)

Over the course of several years, the turbulent overflow stream melted the ice down to create this canyon. By the time this photo was taken, snow had dammed canyon near the lake outlet, meaning it no longer actively drained the lake.

Most of the water in the photo is from melt at the sides of the canyon. The ice is flowing at approximately 100 m/yr, slowly moving the stream outlet toward higher ground so it is unlikely that the lake will overflow at this location again. And instead, we have found a new canyon forming in a lower part of the lake basin.

By Ian Joughin, University of Washington

The EGU’s open access geoscience image repository has a new and improved home at http://imaggeo.egu.eu! We’ve redesigned the website to give the database a more modern, image-based layout and have implemented a fully responsive page design. This means the new website adapts to the visitor’s screen size and looks good whether you’re using a smartphone, tablet or laptop.

Photos uploaded to Imaggeo are licensed under Creative Commons, meaning they can be used by scientists, the public, and even the press, provided the original author is credited. Further, you can now choose how you would like to licence your work. Users can also connect to Imaggeo through their social media accounts too! Find out more about the relaunch on the EGU website.