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Mountains

Imaggeo on Mondays: Life between the arid mountains of Gansu, China

Imaggeo on Mondays: Life between the arid mountains of Gansu, China

Even within Earth’s more arid environments, you can find life!

This featured photo was taken near the Lanzhou Zhongchuan Airport, about 50 km away from Lanzhou city, the capital of Gansu province in Western China. The area lies in a region between the Qinghai-Tibet Plateau and the Loess Plateau, with an elevation ranging from 1,500 m to 2,200 m. The landscape is dominated by a network of ridges and valleys; the Loess Plateau in particular is known for its highly erodible soil.

The region is a typical temperate or semi-arid area receiving just 260-290 mm of precipitation annually with a potential evapotranspiration of about 1660 mm each year, according to the Gaolan and Yongdeng National Meteorological Stations. However, even in these dry conditions, you can still find pockets of agricultural plots nestled between the winding mountain ridges. Farmers in this region commonly rely on an agricultural method called terrace farming, where crops are grown on graduated platforms, resembling wide steps. Often used in dry mountainous environments, the practice not only creates a flat surface for farming, but also reduces soil erosion and efficiently conserves water. The terraced farms in this area are mainly distributed in the valley where lands are irrigated for wheat and maize production.

By Olivia Trani, Communications Officer, and Xiaoming Wang, State Key Laboratory of Cryospheric Science, Chinese Academy of Science, Lanzhou, China

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/.

Imaggeo on Mondays: How erosion creates natural clay walls

Imaggeo on Mondays: How erosion creates natural clay walls

The badlands valley of Civita di Bagnoregio is a hidden natural gem in the province of Viterbo, Italy, just 100 kilometres from Rome. Pictured here is the ‘wall,’ one of the valley’s most peculiar features, where you can even find the wooden structural remains of a trail used for agricultural purposes in the 19th and 20th centuries.

The photograph was taken by Chiara Arrighi, a post-doc research assistant at the University of Florence (Italy), in May last year after climbing roughly 200 metres from the bottom of the Chiaro creek valley. Trails in this region are not well traced or maintained, so she had to find her own way up among the chestnut woods. Once at the top, the trail becomes narrow and unprotected. “The inhabitants of the area still do not exploit this natural beauty as a tourist attraction,” said Arrighi. “In fact, nobody was on the trail, and the silence [was] unreal.”

Badlands are a typical geological formation, where grains of sand, silt and clay are clumped together with sedimentary rock to form layers, which are then weathered down by wind and water. The terrain is characterised by erosive valleys with steep slopes, without vegetation, separated by thin ridges.

Due to the slope’s steep angle and the clay’s low permeability, little water is able enter the soil. Instead water quickly flows across the surface, removing surface clay and carving into the slopes as it does so.

The morphological evolution of the clay slopes can be very rapid (for example, rock falls can occur quite suddenly after heavy rainfall) and occurs as a result of several physical mechanisms, such as mud flows, solifluction (slow movement of wet soil towards the bottom of the valley) and sliding.

During the evolution of the badlands, peripheral portions of the terrain made up of volcanic deposits (tuff cliffs) rose up from the landscape, bordered by nearly vertical slopes (called scarps). Many towns have been built on these erected hilltops, such as Civita di Bagnoregio.

By Chiara Arrighi and Olivia Trani

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/.

Imaggeo on Mondays: The Henry Mountains, living textbook of modern geomorphology

Imaggeo on Mondays: The Henry Mountains, living textbook of modern geomorphology

In 1877, the United States Geological Survey published a report “On the Geology of the Henry Mountains”, on the small range of peaks in southern Utah, pictured here. Up to that point, little scientific study had been made of the unassuming peaks, but the author of the report, one Grove Karl Gilbert, not only detailed the structure and mineralogy of the landscape, but in doing so also laid the foundations for much of modern geomorphology.

While beautiful, the range is isolated and of limited economic value; Gilbert himself notably wrote that “No one but a geologist will ever profitably seek out the Henry Mountains”, while the name given to the range by the Navajo Nation is Dził Bizhiʼ Ádiní, literally meaning “mountain whose name is missing”. And yet, the wildness of the range is sufficient attraction for some!

by Robert Emberson

Robert Emberson is a Postdoctoral Fellow at NASA Goddard Space Flight Center, and a science writer when possible. He can be contacted either on Twitter (@RobertEmberson) or via his website (www.robertemberson.com)

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/.

Imaggeo on Mondays: The ancient guard of Altai

Imaggeo on Mondays: The ancient guard of Altai

In the heart of Eurasia, an ancient stone statue overlooks the expanse of the Kurai Valley and the Altai Mountains in Russia. This relic was crafted more than a thousand years ago, sometime during the 6th or 7th century. A Turkish clan that inhabited the region, known as the First Turkic Khaganat, would often erect stones as monuments of funeral rituals.

Natalia Rudaya, who took this photograph, is a senior researcher at the Institute of Archeology and Ethnography of the Siberian Branch of the Russian Academy of Sciences. She and her research team were taking sediment cores from the bottom of Lake Teletskoye, the largest lake in the Altai Mountains, in southeastern West Siberia, close to the photograph’s location.

The lake samples give clues on how the local environment has shifted over the last couple thousand years, and how these changes might have influenced the human societies that inhabited the Altai Mountains. Investigating palaeoclimates and past vegetation shifts are also important for understanding how current climate change will affect Earth’s ecosystems.

By analysing sediment cores, Rudaya and her colleagues were able to reconstruct the region’s environmental and climatic history. Their results showed that in the beginning of the mid- to late- Holocene (roughly 4,250 years ago), the region exhibited a relatively cool and dry climate, and the land surface was dominated by Siberian pine and Siberian fir forests. However, starting around 3,900 years ago, plant populations faced significant deforestation for roughly three centuries. Then 3,600 years ago, dark coniferous mountain taiga began to extend across the territory; the sediment samples also show that this forest expansion coincided with slight increases in temperature and humidity. This climate persisted for roughly 2,000 years, then the mountainous environment faced cooler temperatures once again.

References

Rudaya, N. et al.: Quantitative reconstructions of mid- to late holocene climate and vegetation in the north-eastern altai mountains recorded in lake teletskoye, Global and Planetary Change., 141, 12-24, 2016

Huang, X. et al.: Holocene Vegetation and Climate Dynamics in the Altai Mountains and Surrounding Areas, Geophysical Research Letters, 45, 6628-6636, 2018.

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/.