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Imaggeo on Mondays: A massive slump

1 Sep

One of the regions that has experienced most warming over the second half of the 20th century is the Potter Peninsula on King George Island in Antartica. It is here that Marc Oliva and his collaborators are studying what the effects of the warming conditions on the geomorphological processes prevailing in these environments.

“Permafrost is present almost down to sea level in the South Shetland Islands, in Maritime Antarctica” says Marc, “in some recent deglaciated environments in this archipelago, the presence of permafrost favours very active paraglacial processes”.

Permafrost is defined as the ground that remains frozen for periods longer than two consecutive years and constitutes a key component of the Cryosphere. However, it is not fully understood how it reacts to climate variability. In this sense, there is an on-going effort to improve our knowledge on these topics by carrying out long–term monitoring of permafrost, as well as of geomorphological processes, in order to better understand the response of the terrestrial ecosystems to recent warming trends.

This weeks’ Imaggeo on Mondays picture shows a massive slump and the exposed permafrost in the shoreline of a lake in Potter Peninsula (King George Island, Maritime Antarctica). Following the deglaciation of this ice-free area paraglacial processes are very active transferring unconsolidated sediments down-slope to the lake.

Slump-permafrost, Potter Peninsula, Antarctica. (Credit: Marc Oliva via imaggeo.egu.eu)

Slump-permafrost, Potter Peninsula, Antarctica. (Credit: Marc Oliva via imaggeo.egu.eu)

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: The Valley of the Souls

25 Aug

Simon Gascoin captured this image of the badlands of the Palca canyon. The Palca canyon is located near the city of La Paz, Bolivia. Like much of the geology in the vicinity of La Paz, the canyon comprises mainly unconsolidated glacial formations, which are highly susceptible to wind and water erosion. The imposing spires, which can reach up to 200m in height, are fluvioglacial deposits that resulted from differential erosion of the sediments by water flow.

The canyon is 8 Km long, with a wide plain flanked on either side by the magnificent pinnacles seen in the photograph below. Bolivia’s second highest mountain, Illimani, towers over the Valley of the Souls (Valle de las Ánimas), adding to the magic of the site.

“Palca Canyon” by Simon Gascoin.  The image is distributed by the EGU under a Creative Commons licence.

“Palca Canyon” by Simon Gascoin. The image is distributed by the EGU under a Creative Commons licence.

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: Loch Leven

18 Aug

Over hundreds and thousands of years, glaciers reshape the landscape beneath them. As they creep forward, the combined weight of the glacier and the perpetual forward movement means the ice continuously erodes away the rock below, permanently changing the terrain.

During the last Ice Age much of Scotland and northern Britain were covered by a thick sheet of ice. Where there might have been once a stream, impenetrable masses of ice pushed their way downwards, widening and carving. As the climate warmed, 10 000 years ago, the ice slowly melted away to reveal broad U-shaped valleys.

David Tanner photographed Loch* Leven, which lies at the bottom of a beautiful U-shaped valley carved out by glaciers during the last Ice Age.

“Loch Leven” by David Tanner. This picture shows a view west along Loch Leven and is distributed by the EGU under a Creative Commons licence.

“Loch Leven” by David Tanner. This picture shows a view west along Loch Leven and is distributed by the EGU under a Creative Commons licence.

“The geology of the valley is very complex” describes David, “There are a series of metamorphosed sediments called the Dalradian (the Celtic name of the area is Dál Riata), which were intensely folded and deformed during the Caledonian Orogeny (in the Devonian)”. The aim of David’s work was to unravel the folding history of the rocks, because, as David explains “the deformation history of the Dalradian, compared to the rest of Scotland, is still poorly understood”. Detailed mapping revealed four different folding episodes.

*(the Celtic word for lake).

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: The most powerful waterfall in Europe

14 Jul

On the menu this Monday is the opportunity to indulge in some incredible Icelandic geology. Take a look at a tremendous waterfall and the beautiful basalt it cuts through…

Iceland is famous for its striking landscapes, from fiery volcanoes and fields of basalt to violent geysers and pools of the most fantastic blue. One of the country’s many geological gems is Dettifoss waterfall – a 100-metre-high mass of white, tumbling water within Vatnajökull National Park.

With about 200 cubic metres of water falling each second, Dettifoss is widely reported to be the most powerful waterfall in Europe. It certainly looks the part.

Dettifoss waterfall, Iceland (Credit: Neil Davies, via imaggeo.egu.eu)

Dettifoss waterfall, Iceland (Credit: Neil Davies, via imaggeo.egu.eu)

Dettifoss is fed by melt from the Vatna Glacier (Vatnajökull), and the spring spike in meltwater means the fall’s flow can reach some 1500 cubic metres per second. By putting your hand to the rocks beside the fall you can feel the thundering torrents as the basalt vibrates beneath your fingertips.

The Jökulsá river snakes through the park’s volcanic canyons, which are constantly being cut by the erosive force of the fall. Dettifoss isn’t the only great feature in this photo though: the canyon walls are layered with lava flows that – even at a glance – reveal when they were deposited. The relatively smooth deposit at the base of the wall and the thinner skin of smooth basalt in the middle are the product of interglacial eruptions. The two rough, blocky-looking layers are columnar basalt deposits – a feature that forms when lava meets ice and cools so rapidly that it fractures into long, hexagonal columns.

Dettifoss up close. (Credit: Roger McLassus)

Dettifoss up close. (Credit: Roger McLassus)

For many geoscientists, Iceland is the top spot on the geological destination list. If you went to Iceland, where would you go? Been before? Tell the tale. We’d love to hear from you.

By Sara Mynott, EGU Communications Officer

Reference:

Bamlett, M., and Potter, J. F.: Icelandic geology: an explanatory excursion guide based on a 1986 Field Meeting. Proceedings of the Geologists’ Association 99.3, 221-248, 1988.

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.

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