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Field Work

Imaggeo on Mondays: Probing the Pliocene

Imaggeo on Mondays: Probing the Pliocene

The heights we go to for science…

This photograph shows a member of our team preparing to abseil down a cliff in the Charyn Canyon, in the Ili River basin of southeast Kazakhstan. The Charyn River and its tributaries, a branch of the Ili River north of the Tien Shan Mountains, have cut canyons up to 300 metres deep, carving through rocks of different geologic ages, some as old as 540 million years.

The name “Charyn” may derive from local Uighur or Turkic words for “ash tree” or “precipice” respectively, both of which are common in the area.

Charyn Canyon is presently characterized by a cold semi-arid climate, with dry summers and cold winters. However, these conditions are likely to have varied through time, becoming wetter, drier, warmer and cooler in response to major climate systems’ changing intensity and influence over the region.

Our research team investigates the past and present climate systems of the Cenozoic era, our current geological era which began 66 million years ago; the most recent 2.6 million years have been characterised by alternating ice ages and warmer so-called “interglacial” phases, and saw the evolution of humans. More specifically, we study climate systems in one of the most remote regions of Central Asia, known as the Eurasian Continental Pole of Inaccessibility. The area is a challenging place for climate research since it has no marine or ice core records, the most common calendars of ancient climate.

This region is poorly understood yet important within the global climate system, since it lies at the boundaries of the major northern hemispheric climate systems. These systems, such as the Siberian high pressure system and Asian monsoons, are likely to have shifted, expanded and contracted over time. These changes occur in response to factors like mountain uplift, and changes in the Earth’s orbital patterns and incoming solar radiation.

The aim of our study is to reconstruct climatic change over this period. By analysing various chemical and physical characteristics of the sediments, such as their age, magnetism, grain size and chemistry, we can reconstruct quantitative palaeoclimatic variability through time.

Here we focus on an 80-metre thick layer of sediment, which alternates between layers of river-transported gravels and wind-blown dust deposits, known as loess. Younger sedimentary layers have thicker dust deposits, reflecting a long-term aridification trend in the Ili Basin and, more broadly, Central Asia.

Our preliminary results from our fieldwork indicate that the canyon’s sediments represent an uninterrupted representation of the region’s climate from the Pliocene to early Pleistocene (from approximately 4.5 to 1 million years ago).

Achieving a comprehensive geological sampling of the Charyn Canyon was only possible by abseil. Our fieldwork, undertaken from May to June 2017, was a hot and dusty business, but ultimately a lot of fun. Definitely not for those with a fear of heights!

By Kathryn Fitzsimmons, Max Planck Institute for Chemistry, Germany and Giancarlo Scardia, São Paulo State University, Brazil

Imaggeo on Mondays: Iceland’s original birch forest

Imaggeo on Mondays: Iceland’s original birch forest

Iceland is a country of dramatically rugged landscapes. The region is home to sweeping valleys and mountain ranges, dotted with lava fields, large glaciers, hot springs and impressive waterfalls.

The territory is also notoriously treeless. As of 2016, forests only made up 1.9 percent of Iceland, according to the Icelandic Forest Service. However, about a thousand years ago the country’s landscape was far more vegetated, and remnants of Iceland’s original woodlands still exist today.

It is a common misconception that Iceland is too cold to sustain a forest. “On the contrary, it has been observed that, at the time of human settlement, birch woods and scrubs have covered large parts of Iceland,” said Marco Cavalli, a researcher at the Research Institute for Geo-Hydrological Protection in Italy and the photographer of today’s featured image. In fact, Iceland’s fossil evidence suggests that, before human settlement, 25-40 percent of the island was dominated by woodlands and thickets.

When humans migrated to the island about 1100 years ago, much of Iceland’s natural forests were chopped down to make way for fields and pastures. In the centuries following human settlement, intensive sheep grazing and volcanic eruptions prevented forests from regenerating. By 1950, less than one percent of the country was covered by trees.

Iceland’s vegetation-devoid state presents an environmental problem to local Icelanders, since the lack of trees, combined with the island’s volcanic activity, has left the land vulnerable to severe soil erosion. Since the soil conditions prevent vegetation from taking root, erosion has limited farming and grazing efforts. Iceland’s loose soil and strong winds are also responsible for damaging sandstorms.

Soil conservation and forestry services have made substantial efforts to repopulate the Icelandic environment with trees, just about doubling Iceland’s tree cover since the mid-20th century. However, there is still a long road ahead to reach the Icelandic Forest Service’s goal to see 12 percent of Iceland afforested by 2100.

This picture was taken by Cavalli while on a field trip in Rangárvellir, a southern region of Iceland near Gunnarsholt, the headquarters of the Soil Conservation Service of Iceland (SCSI). The workshop focused on the area’s severe degradation from both human activities and natural causes, and efforts to restore the ecosystem.

During the workshop he spotted this particular grove of dwarf birch trees. “I was impressed to see a small remnant patch of the Icelandic original birch forest resisting all these adverse conditions,” said Cavalli. “I would say this is a good example of nature fighting to survive.”

References

Forestry in a Treeless Land, Icelandic Forest Service

Changes in vegetation cover from the time of Iceland’s settlement, Icelandic Institute of Natural History

Vikings Razed the Forests. Can Iceland Regrow Them?, The New York Times

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Announcing the winners of the EGU Photo Competition 2018!

The selection committee received over 600 photos for this year’s EGU Photo Contest, covering fields across the geosciences. Participants at the 2018 General Assembly have been voting for their favourites throughout the week  of the conference and there are three clear winners. Congratulations to 2018’s fantastic photographers!

 

Foehn clouds in Patagonia,’ by Christoph Mayr (distributed via imaggeo.egu.eu). A stationary cloud formed on the lee side of Mount Fitzroy. It evolved from a lenticular cloud (Altocumulus lenticularis) and turned into a funnel-shaped cloud during sunset when the photo was taken.

 

Jebel Bayda (White Mountain),’ by Luigi Vigliotti (distributed via imaggeo.egu.eu). An aerial view of the Jebel Bayda, a white volcano created by silica-rich lava (comendite) in the Khaybar region. The flank of the volcano was shaped by rain in the region during the first half of the Holocene.

 

Remains of a former ocean floor,’ by Jana Eichel (distributed via imaggeo.egu.eu). These limestone boulders characterise the landscape of Castle Hill Basin in New Zealand’s Southern Alps. The Pacific Plate collided with the Australian Plate during the Kaikoura Orogeny 25 million years ago, giving birth not only to the Southern Alps but also lifting up thick limestone beds formed in shallow ocean water.

 

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submittheir photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Photo Competition finalists 2018 – who will you vote for?

The selection committee received over 600 photos for this year’s EGU Photo Competition, covering fields across the geosciences. The fantastic finalist photos are below and they are being exhibited in Hall X2 (basement, Brown Level) of the Austria Center Vienna – see for yourself!

Do you have a favourite? Vote for it! There is a voting terminal (also in Hall X2), just next to the exhibit. The results will be announced on Friday 13 April during the lunch break (at 12:15).

Remains of a former ocean floor.’ Credit: Jana Eichel (distributed via imaggeo.egu.eu). These limestone boulders characterise the landscape of Castle Hill Basin in New Zealand’s Southern Alps. The Pacific Plate collided with the Australian Plate during the Kaikoura Orogeny 25 million years ago, giving birth not only to the Southern Alps but also lifting up thick limestone beds formed in shallow ocean water.

 

Foehn clouds in Patagonia.’ Credit: Christoph Mayr (distributed via imaggeo.egu.eu). A stationary cloud formed on the lee side of Mount Fitzroy. It evolved from a lenticular cloud (Altocumulus lenticularis) and turned into a funnel-shaped cloud during sunset when the photo was taken.

 

Jebel Bayda (White Mountain).’ Credit: Luigi Vigliotti (distributed via imaggeo.egu.eu). An aerial view of the Jebel Bayda, a white volcano created by silica-rich lava (comendite) in the Khaybar region. The flank of the volcano was shaped by rain in the region during the first half of the Holocene.

 

Mother-of-pearl cloud.’ Credit: Thomas Kuhn (distributed via imaggeo.egu.eu). These clouds are a special type of polar stratospheric clouds that only occur during the polar winter. The tiny ice crystals that form in these clouds must be uniform in size so that diffraction can create their shining colours.

 

Patagonian rainforest.’ Credit: Carsten W. Mueller (distributed via imaggeo.egu.eu). The magic light in the Patagonian rain forest is dominated by Southern beech (Nothofagus). The high precipitation in Southern Patagonia sustains biodiverse rainforests on peaty soils.

 

The beauty of shells.’ Credit: Rene Hoffmann (distributed via imaggeo.egu.eu). A thin section of a belemnite (Gonioteuthis, Upper Cretaceous, NW-Germany) under crossed polarizers. Belemnites are the backbone of Jurassic-Cretaceous reconstruction as they able to determine former seawater properties, such as temperature.

 

50 shades of grey.’ Credit: Paolo Paron (distributed via imaggeo.egu.eu). The dry sandy river bed of the Limpopo River. This picture was taken at the end of January, in the middle of the rainy season, and shows the devastating effects of the prolonged drought. The surrounding floodplain that is used extensively by farmers would normally be inundated.

 

Pinnacles in Nambug National Park at sunset.’ Credit: Stefan Doerr (distributed via imaggeo.egu.eu). The spectacular pinnacle karst in Western Australia. This landscape contains thousands of pinnacles up to 5 m high and 2 m wide. The pinnacles have formed in the Pleistocene Tamala Limestone, which comprises cyclic sequences of aeolian calcarenite, calcrete / microbialite and palaeosol.

 

Closer look at the deglaciation history of Lago Belgrano.’ Credit: Monika Mendelova (distributed via imaggeo.egu.eu). The Lago Belgrano valley was once occupied by a glacier, which drained part of the Patagonian Ice Sheet. The retreating glacier allowed a large palaeo-lake to form, a predecessor of modern Lago Belgrano. Spot the shoreline!

 

Poetry of water shaped formations.’ Credit: Raphael Knevels (distributed via imaggeo.egu.eu). This karst cave was discovered in 2005 and named Paradise Cave because of its exceptionally beautiful stalactites and stalagmites. The cave is located in the Phong Nha-Kẻ Bàng National Park, Vietnam.

 

The EGU General Assembly is taking place in Vienna, Austria from 8 to 13 April. Check out the full session programme on the General Assembly website and follow the Assembly’s online conversation on Twitter at #EGU18.