GeoLog

This week’s Imaggeo on Mondays is brought to you by the photographer herself, Jana Eichel, who tells us about her expedition to the Mingsha Mountains and the stunning aeolian landforms that characterise the landscape.

“Star dune in the Gobi desert, Dunhuang, China” by Jana Eichel, distributed by the the EGU under a Creative Commons licence.

This photo was taken during a journey through Asia in spring 2012, which took me across Bangladesh, India and Nepal through to Western China and into the Gobi Desert. This journey allowed me to appreciate the enormous variety of landscapes in Asia as well as  the different cultures. To experience ‘the desert’, which has fascinated me for quite a while, I joined  four others on an (ever so slightly touristy) overnight camel trek to the borders of the Mingsha Mountains, where this photo was taken. This megadune field is located south of Dunhuang (Gansu province, China) in the Gobi Desert. The dunes, which are aeolian depositional landforms, are between 60 and 170 m heigh and are formed mostly by westerly and southerly winds. In the neighborhood of this dunefield, the World Cultural Heritage of the Mogao Caves is located, which house a large collection of Buddhist art. There is a fear that they will be overrun by the Mingsha Mountains (megadunes) in the future, which are slowly advancing in this direction.

The Gobi Desert (source).

The image was taken from near the top of one of the large pyramid dunes at the northeastern border of the dunefield. From here you can see the foothills of the Mingsha Mountains with various dune types, which are determined by a multitude of influencing factors, including wind direction variability and sand supply. Our camp in the lower left of the picture puts these huge landforms into perspective.

Most prominently in the foreground next to the camp is a star-shaped dune. These dunes are generally formed by multidirectional winds when there is a large sand supply. These conditionscreate a set of slip faces that project out in  multiple directions, such that the dune represents a star – hence the name! Transverse dunes and barchanoid ridges can be seen in the background, where they phase out towards the plains, likely dues to a decreasing sand supply. Dunefields such as this, with a variety of dune types highlight the complexity of geomorphic systems, Aeolian systems, such as the one here are thought to be strongly driven by self-organisation. This means the complex non-linear dynamics of the system do not result in chaos but instead in order: the smallest elements in the system, such as the sand grains, assemble into larger scale objects, such as the dune patterns shown (Dikau, 2006). This emergent behaviour cannot be predicted even if all processes fundamental for the evolution of these dunes are known.

To account for the impressive landscape with its large-scale geomorphic forms, I used a high aperture to give the picture a greater depth. This was amplified by the sunset light, which  created long shadows behind the dunes and gave a better impression of the contours of the dunes, which are partly obscured during the day.

By Jana Eichel, University of Bonn  

References:

Dikau, R. (2006): Complex systems in geomorphology. Mitteilungen der Österreichischen Geographischen Gesellschaft 148, 125-150.

Jianjun, Q., Ning, H., Guangrong, D. and Weimin, Z. (2001): The role and significance of the Gobi Desert pavement in controlling sand movement on the cliff top near the Dunhuang Magao Grottoes. Journal of Arid Environments 48, 3, 357-371.

Kocurek, G. and R.C. Ewing (2005): Aeolian dune field self-organization – implications for the formation of simple versus complex dune-field patterns. Geomorphology 72, 94-105.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their images to this repository and since it is open access, these photos can be used by scientists for their presentations or publications as well as by the press and public for educational purposes and otherwise. If you submit your images to Imaggeo, you retain full rights of use, since they are licensed and distributed by EGU under a Creative Commons licence.

Nothing captures beauty of Arizona’s landscape better than the Grand Canyon and its steeply-sided cliffs that have been carved by the Colorado River. This photo by Lukas Hoertnagl shows this stunning landscape as seen from Lipan Point in the Grand Canyon National Park.

“The Grand Canyon Symphony” by Lukas Hoertnagl. Distributed by the EGU under a Creative Commons licence.

The early geological history of America is preserved in the strata that make up the Grand Canyon’s famed banded landscape, which is composed of nearly 40 clear strata and over 100 rock units – from a 2 billion year-old metamorphic/igneous basement to the park’s dusty surface. Much of the canyon’s strata weren’t exposed until the Colorado River began to snake its way across the landscape.

Lipan Point (A) in the Grand Canyon National Park. Source: Google Maps.

After more than 150 years of study, though, Geologists are still working to understand the processes leading to the canyon’s formation. The biggest question? How the Colorado River came to take this course and start slicing the canyon cake.

The Colorado River as we know it, formed approximately 6 million years ago, following a change in the direction of many streams, which directed water towards a lower region of the Colorado Plateau. The confluence of these streams led to the formation of a large, down cutting river, which since then has sliced through over 1,800 metres of rock. The Colorado River did not have significant erosive power until it was integrated over the Great Welsh Cliffs and it while it flows from the Rockies in the East out West towards the Gulf of California today, this was not always the case.

This is where it starts to get hazy: what caused the course of the river to change? Was it rifting? Sinking of the Colorado Plateaux? A drastic change in the drainage patterns of the Colorado basin? Or was there something else contributing to the change in river flow? For now at least, the jury is out.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their images to this repository and since it is open access, these photos can be used by scientists for their presentations or publications as well as by the press and public for educational purposes and otherwise. If you submit your images to Imaggeo, you retain full rights of use, since they are licensed and distributed by EGU under a Creative Commons licence.

Short Courses

Open Access (OA)

Demystifying Open Access – an open discussion for early career researchers tackling how OA can benefit young scientists without compromising their careers. From what it costs to publish an open access paper to how we can measure its impact, all interested scientists are invited to drop in and join us over drinks in a marketplace of discussion.

How to apply for a job. It’s a topic rarely addressed in postgraduate courses, but in this session, career training experts will help you make the most of your strengths and show them off to a potential employer. Pick up some tips about finding the right job for you, preparing a good CV, and writing a targeted cover letter.

The Blogs and social media in scientific research session explores the ways in which scientists can use blogs and social media to communicate their work. Why should scientists blog or use Twitter?  How do they find the time? And what are the benefits? A panel of blog and social media-savvy scientists will talk about their experience before opening the discussion to the audience.

Last year’s communicate your science workshop

If you’re a Geomorphologist, you’ll be set for the week as the Geomorphology division has loads on offer! Pickup skills on dating techniques, project supervision, open access publishing  and you can also meet the master for tips from seasoned academics.

If you’re a Hydrologist, there’s also the opportunity to meet experts in the field in a round-table discussion with established scientists. You can also pick up pointers on writing the perfect hydrology paper.

See the session programme for more short courses at EGU 2013.

Meeting other Geoscientists during the tweet up at last year’s General Assembly.

Networking

The opening reception on Sunday, 7 April is a great opportunity to meet people, network, get to know the Assembly venue. There is free food and drink as well as specific places for Young Scientists to meet up on the Green Level. Tall signs will tell you where to go, so stop by to meet fellow early career researchers, division presidents and the Young Scientist representatives for the EGU (Jennifer Holden and Sara Mynott).

Earlier in the day, there will also be an opportunity for women in the geosciences to attend a networking event run by the Earth Science Women’s Network, for more information and how to register, see here.

Check this post for more details on networking opportunities at the General Assembly.

Have your say!

What would you like us to do for you? Join us over lunch (food provided!) to find out what the EGU can do to for Young Scientists and let us know what you’d like more of. These will take place on Tuesday 9 April and Thursday 11 April.

Other Sessions

The Medal Lectures, which highlight the work of brilliant scientists. Head on over to the lectures on the Arne Richter Award for Outstanding Young Scientists (ML4-ML7) and be inspired!

You can also join in a conference call for Young Researchers in Earth Sciences, which aims to promote interdisciplinary research efforts among early career researchers.

These are the outwash plains for the Icelandic volcano, Katla:

“Sandstorm, Myrdalssandur outwash plain, Iceland” by Ragnar Th Sigurdsson. This image is distributed by the European Geosciences Union under a Creative Commons licence.

An outwash plain (or sandur) is a broad, shallowly sloping region ahead of a glacial front. They are made up of material that has been deposited by glacial meltwater, released either by geothermal heating or a subglacial eruption. The extensive volcanism and abundance of ice-capped volcanoes in southern Iceland means that the outwash plains are particularly well developed here.

The Mýrdalssandur outwash plain in relation to the volcano Katla (Mýrdasljökull) [source: Jóhannesdóttir and Gísladóttir, 2010].

Between flooding events, some vegetation takes hold, but much of the soil is loose and easily transported by wind. Indeed, the soil islands you see in the photo are formed by wind-blown soil and if they were to erode, the area would be a desert consisting of glacial alluvial sediments alone. Sandstorms, such as the one above, carry fine particulate matter (clays and glacial till) from the outwash plains to other areas and even contribute to the particulate pollution in Reykjavík, some 110 km away!

References:

Jóhannesdóttir, G. and Gísladóttir, G.: People living under threat of volcanic hazard in southern Iceland: vulnerability and risk perception, Natural Hazards Earth System Science, 10, 407-420, doi:10.5194/nhess-10-407-2010, 2010.

Thorsteinsson, T., Gísladóttir, G., Bullard, J. and McTainsh, G.: Dust storm contributions to airbourne particulate matter in Reykjavík, Iceland, Atmospheric Environment, 45, 5924-5933.

Warner, N.H.: Catastrophic outwash plains on Earth and Mars: comparisons from Iceland and Chasma Boreale, Mars. PhD thesis, Arisona State University, December, 2008.

You can find more Arctic images from Ragnar Th Sigurdsson here, and more from the Imaggeo open access database here.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their images to this repository and since it is open access, these photos can be used by scientists for their presentations or publications as well as by the press and public for educational purposes and otherwise. If you submit your images to Imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

Picture yourself in the Himalaya mountain belt: millions of years of continental uplift have produced a vast kingdom of towering monoliths, and they continue to grow as the Indian plate pushes further north into the heart of Asia. These dramatic, breath-taking and downright enormous geological structures can be simplified into the following tectonic units: the Leugogranites, the Transhimalaya, the Suture Zone, the Tethys Himalaya, the High Himalayan Crystalline Sequence and the Lesser Himalaya.

Himalayan geology, showing exactly where you can find the view below! [modified after O'Brien, 2011]

“Ladakh” by Franziska Wilke. The Indus River feeds the agricultural oasis in Franziska’s photo, a vivid contrast to the surrounding geology! Distributed by the EGU under a Creative Commons licence.

This view is to the south, where the Tethyan Sedimentary Zone overlies the Higher Himalayan Crystalline (HHC). The HHC has been thrust southward onto the Lesser Himalaya through the northward progression of the Indian plate and the resulting stacked sequence forms a barrier to rainfall so that regions to the north are only marginally affected by the monsoon. One such area is the Tso Morari. The Tso Morari Crystallines contain large eclogite bodies (up to a metre across!). Eclogites are very dense bodies of rock that form under pressures far greater than those at the Earth’s crust (over 1.2 Giga Pascales). The eclogites found here contain a mineral assemblage that reflects this: garnet, rutlie, coesite and quartz to name just a few!

Franziska studied Kaghan eclogites, sampled during a former field campaign in Pakistan by her supervisor, Professor  Patrick O’Brien. Since travelling in Pakistan was, and is, quite dangerous these days, she decided to attend the Himalaya-Karakoram-Tibet Workshop in northern India rather than going to Pakistan herself, because she wanted to see the Himalayan eclogites and their relation to their host rocks. Besides having fun sampling rocks, she also enjoyed the breath-taking landscape and the opportunity to take marvellous pictures.

O’Brien, P. (2011) Subduction followed by collision: Alpine and Himalyan examples. Physics of the Earth and Planetary Interiors 127, 277-291.

P. Dèzes (1999). Tectonic and Metamorphic Evolution of the Central Himalayan Domain in Southeast Zanskar (Kashmir, India). PhD Thesis. Institut de Mineralogie et Petrographie, Université de Lausanne. No. 32, ISSN 1015-3578

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

After studying ‘Applied Environmental Sciences’ I decided to go with a friend for six months to New Zealand for the southern hemisphere winter. Leaving as soon as my diploma thesis (on epiphytic lichens) was written, we set off into the distance to work and travel. We chose New Zealand as our dream destination because these two islands have so many different landscapes to offer – and this is how I was able to capture this picture:

“Honeycomb Weathering” by Stefanie Boltersdorf (University of Trier, Germany), taken on the Kaikoura Peninsula, New Zealand. This photo is distributed by the European Geosciences Union under a Creative Commons License.

The photo shows honeycomb weathering on the Kaikoura Peninsula, with extends from the East coast of the South Island. Composed of mudstone and limestone, the terraces were once wave-cut platforms and have since been uplifted and deformed (during the Quaternary). The peninsula extends into the sea and encounters the relatively shallow Chatham Rise, an area of ocean floor to the east of New Zealand that was largely dry during the Cretaceous period, but now lies nearly 1000 metres underwater. This area is also one of the region’s most productive fishing grounds, a consequence of the nutrient-rich water that upwells along the coast. At low tide, the ocean gives way to a rocky floor, which is easily navigable by foot for quite some distance – and from there you can have a better view of the local seals and seabirds. At this spot, a branch of the Southern Alps, the so-called Seaward Kaikoura Range, comes close to the sea.

Very early in the morning, after sleeping next to the sea and having breakfast in our small van, ‘Berty’, the tide was very low and we took the opportunity to go for a walk. It was on this adventure we found this stunning structure, peppered with small molluscs that were sheltering in the eroded depressions. These depressions are a consequence of honeycomb weathering – a process initiated when salt meets porous rock. Sea spray delivers salt to the rocks, which, after the water has evaporated, is deposited in the pore spaces. Over time, the salt crystals push the minerals apart and weaken the rock. Small pockets collect seawater and erode into ever-larger depressions, eventually creating this marvellous honeycomb structure.

Although I have been dealing with epiphytic lichens during my diploma thesis, I remained true to them, even after my trip. After my return, and inspired by my trip to the highly lichen-rich New Zealand, I started my PhD thesis – investigating a method of quantitatively and qualitatively assessing nitrogen deposition in lichens, with the help of stable isotopes.

By Stefanie Boltersdorf, with Geo-facts from Sara Mynott

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

“Kalalau Valley” by Martin Mergili, taken from Kalalau Lookout on the island of Kauai, distributed by the European Geosciences Union under a Creative Commons License.

At over 5 million years old, the island of Kauai is the oldest island in the Hawaiian Achipelago. Hawaii, Maui and Oahu are all younger and lie further to the southeast. This island chronology is no coincidence – the Archipelago formed as a result of intra-plate volcanic activity.

Intra-plate volcanism occurs where an upwelling magma plume or ‘hot spot’ lies beneath a continental plate. In this case, the Pacific Plate has moved over a hot spot in the northwestern direction, so that the younger and more active islands are located in the southeast, and the older islands are further north. As the plate passes further from the hotspot, the crust cools, becoming less buoyant and causing the oldest islands in the chain to sink and form atolls when fully submerged.

Volcanic has ceased on Kauai and now erosive forces are those that shape the island, resulting in deep gullies and canyons cut into the highlands. In the north and northwest of Kauai the roaring waves of the Pacific Ocean hit the island after travelling for thousands of kilometres undisturbed. These waves meet a steep and rugged coastline with swells that can reach 10 m high on the Na Pali Coast. Running water has cut spectacular valleys into these cliffs, forming the Nualolo and Awaawapuhi, and Kalalau (above) Valleys. During the summer, carbonate sands fringe the island – you can just about see them here, but they are washed away by heavy wave action in the winter months.

This view of the Kalalau Valley was captured by Martin Mergili (Geologist from BOKU, University of Natural Resources and Life Sciences, and keen photographer), who explains that he took “this photo on a holiday trip to Hawaii in August 2010 (as far as a geoscientist can spend a “real” holiday in Hawaii). The viewpoint is called Kalalau Lookout, located in the humid highlands of Kauai, close to the misty Alakai Swamps and Mount Waialeale, one of the wettest places on Earth”.

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

“Rainbow in stone” by Marina Manea, distributed by the European Geosciences Union under a Creative Commons licence.

Nothing better characterises the wild US West than endless landscapes of red hoodoos, spires of rock protruding from the bottom of an arid drainage basin or badland. Found mainly in desert and dry, hot areas, hoodoos are distinctive from similarly-shaped formations, such as spires or pinnacles, because their profiles vary in thickness throughout their length. Their distinctive colour bands are the product of erosional patterns differentially affecting layers of harder and softer minerals.

Nowhere in the world are hoodoos as abundant as in the northern section of Bryce Canyon National Park in Utah, USA. There, these formations, also known as goblins or in French as demoiselles coiffées (“ladies with hairdos”), dominate the landscape.

At Bryce Canyon, hoodoos are formed by two continuously operating weathering processes. The first, frost wedging, occurs as a result of Bryce’s over 200 annual freeze/thaw cycles. In the same way potholes are formed on a paved road, water breaks open the rock when it seeps into cracks, freezes, and expands. Secondly, the hoodoos are also sculpted by rainfall, both physically, because it removes debris, and chemically, because its slightly acidic pH dissolves the limestone.

Marina Manea, who works in the Computational Geodynamics department of the Universidad Nacional Autonoma de Mexico, took this early-morning picture from a helicopter whilst on holiday in Utah in August 2010. She explains, “Bryce Canyon has a unique geology, with deposits from the late Cretaceous and early Cenozoic eras. It is not a classical canyon but, rather, a collection of amphitheaters modelled by the erosional force of frost-wedging and the dissolving power of rainwater acting on the colorful limestone rock of the Claron Formation. In this way, the spires, or ‘hoodoos,’ are formed. The rocks forming the hoodoos are limestone (sedimentary rocks) exhibiting beautiful colours (red, orange, or white). The entire geology of the Bryce Canyon is related to the geology of the Grand Staircase region and Black Mountains volcanic complex. It rained just before this picture was taken, which explains the exceptionally vivid colours on display here.”

The area around Bryce Canyon was originally settled by Native Americans and later by Mormon pioneers. The national park was established in 1928 and today around 1.3 million (2011) people annually travel to witness its wild terrain and spectacular sunset colours.

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

“Ellesmere Island” by Jean-Daniel Champagnac, distributed by the European Geosciences Union under a Creative Commons licence.

Located within the Canadian Arctic Archipelago, Ellesmere Island is the world’s tenth largest island and features Canada’s most northerly point but little else apart from vast landscapes of pristine natural habitat. It is separated from Greenland only by the Nares Strait, a major pathway for sea ice flushing out of the High Arctic.

Belonging to the Canadian territory of Nunavut, Ellesmere’s permanent population is under 200, most of whom endure the hostile weather found at Grise Ford, where the annual temperature is a staggering -16.5°C.

It comes as no surprise, then, that this mosaic of colours was captured from high above Ellesmere’s unforgiving environment. Jean-Daniel Champagnac, of the Geological Institute of the Swiss Federal Institute of Technology, Zurich, explains, “This picture was taken through the window of an airplane cruising at around 10,000m en route between Frankfurt, Germany and Anchorage, Alaska. Here you can see the bare rock of Ellesmere Island, with presumably folded sedimentary rocks, and a frozen fjord being unglaciated. This picture, taken in June 2011, has been quite substantially modified from the raw initial picture.”

As with many untouched Arctic environments, it is thought Ellesmere may be rich in natural resources, specifically in thermal coal deposits used to produce heat and electricity. If confirmed, this finding could be pivotal for the future of Nunavut. Canada’s mostly-aboriginal territory (83.6% Inuit, according to the 2006 census) is currently experiencing an energy crisis.

About his picture, Champagnac concludes, “It is always worth having a camera along when you fly, especially on a clear day.” We couldn’t agree more and we encourage you to submit more of your aerial shots to Imaggeo.net.

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

“Trees of time” by Pedro Machado, distributed by the European Geosciences Union under a Creative Commons license.

The Namib-Nauklufy National Park in Namibia is a stunning ecoregion that encompasses part of the Namib Desert and the Nauklufy mountain range. With an area of almost 50,000 square kilometres, the park covers a wide range of landscapes, including gravel plains, tall sand dunes, and an ephemeral river. The park also includes one of the main visitor attractions of Namibia, the Sossusvlei, a large dry lake or pan – surrounded by giant dunes – that only fills with water on the rare occasions that it rains in this part of the Namib-Nauklufy National Park.

It was there that Pedro Machado, a researcher at the Centre for Astronomy and Astrophysics of the University of Lisbon in Portugal, captured this interesting, if alien, scenario of dead trees and bright, contrasting colours. “More precisely, the picture was taken in Deadvlei, an awe-inspiring white clay pan situated in the salt pan of Sossusvlei,” he explains. “The old acacias (commonly known as Camel Thorn trees) died 500-1000 years ago, but as there is no humidity in this place, they did not rot, forming a beautiful fossilized forest.”

The vast Namib Desert streches over 2,000 km along coastal Angola, Namibia, and South Africa. It is the world’s oldest desert, having endured arid or semi-arid conditions for at least 55 million years. Pedro says, “For me, the Namib Desert is one of the most beautiful deserts. It has incredible colour gradients on the ground that produce colourful kaleidoscopes when the sun is low on the horizon.”

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.