GeoLog

Mountains

Imaggeo On Mondays: Reservoir in the Italian Alps

Imaggeo On Mondays: Reservoir in the Italian Alps

Mountain natural streams and reservoirs have a relevant hydrological and ecological importance since they represent reliable sources of freshwater supply to lowland regions and high-quality habitats for fish and cold-water communities. Moreover, streams in mountain environments are of significant importance for users in several socio-economic sectors, such as agriculture, tourism and hydropower.

Given the vulnerability of mountain streams and catchments to the impact of climate changes and the increasing concern about water supply in mountain regions, there is the urgent need for scientists to face integrated, multidisciplinary catchment-scale studies addressing implications of climate change on water resources management and flow regimes.

Description by Daniele Penna, as it first appeared on imaggeo.egu.eu

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: Cordillera de la Sal

Imaggeo on Mondays: Cordillera de la Sal

The photograph shows the Valle de la Luna, part of the amazing Cordillera de la Sal mountain range in northern Chile. Rising only 200 metres above the basin of the Salar de Atacama salt flat, the ridges of the Cordillera de la Sal represent a strongly folded sequence of clastic sediments and evapourites (salt can be seen in the left portion of the image), with interspersed volcanic material.

This formation evolved when the depression between the Cordillera Domeyko mountain range and the main Andean mountain ranges, filled by an ancient salt flat, was squeezed together over the last 10-15 million years, leaving behind the folded belt of hills seen today. Sand brought along from adjacent areas by the winds was caught between the ridges of the Cordillera de la Sal, accumulating to form the impressive dune shown in the foreground of the image.

Under normal conditions, the perfectly shaped Licancabur Volcano, forming the border between Chile and Argentina, would appear in the background of this sunset scene. However, the image was taken during the Invierno Boliviano (Bolivian winter), when humid air from the eastern side of the Andes travels west across the Andean Plateau, Altiplano. The air masses journey all the way to the otherwise extremely arid Atacama Desert, bringing clouds, rain and occasionally even hail.

I have been to this area three times: first for vacation, then two times for excursions with students, most recently in February this year. Interestingly, the weather was as to be expected for the Atacama Desert only one time. For the two other times, the weather was looking like this photograph, so it is hard for me to believe that the Atacama would be as arid as people always say. However, indeed, the pieces of geological and geomorphological evidence, such as the folded layers of the Cordillera de la Sal, clearly indicate its extreme aridity, prevailing for tens of millions of years!

By Martin Mergili, University of Vienna

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: Mola de Lord

Imaggeo on Mondays: Mola de Lord

From the easterly Atlantic waters of the Bay of Biscay to the Catalan wild coast (Costa Brava) in the west, the Spanish Pyrenees stretch 430 km across the north of the country. At the foothills of the Catalan Pyrenees you’ll find the Pre-Pyrenees. Despite not reaching the soaring heights of the peaks of the Pyrenees, they nonetheless offer important insights into the geology of the range and stunning panoramas, such as the one featured as today’s Imaggeo on Mondays image. In today’s post, Sarah Weick, a researcher at the Georg August University in Göttingen, explains why the foothills of the mountain belt are a structural geologist’s playground.

The picture was taken from the top of the flat-topped mountain ‘Mola de Lord’, with a beautiful view over the turquoise-blue water of the river Cardener and growth folds, characterised by a significant increase in throw with depth, caused by their syn-sedimentary development The over 1000 m-high mountain belongs to Vall de Lord, close to the Sant Llorenc Growth Structure, formed of folded sedimentary rocks of marine and continental origin that developed from Eocene to Oligocene and display local angular unconformities (where horizontally parallel sedimentary rocks are deposited atop previously tilted layers). Moreover, it is excellently preserved as a structure in the footwall of the Pyrenees and helps to understand how sedimentary deposits are reorganized during the development of a syn-sedimentary growth structure and how they may distribute between the foreland basin and the mountain belt. Outcrops on the mountain top are of conglomeratic composition with clasts and fossilized nummulites – lense-shaped single-celled sea creatures with shells that lived from Paleocene to Oligocene.

As a geologist, Mola de Lord is not the only remarkable location in Catalonia. On a greater scale, the table mountain belongs to the Spanish Pyrenees. There, hikers can experience parts of untouched nature, and witness the mountain’s geological past: from eroded carbonate karsts with unique shapes to the Ebro basin.

The Pyrenees are located in southwest Europe on the border between France and Spain. The Upper Cretaceous to Miocene collision and subduction of the Iberian microplate under the European plate initiated the orogeny, which went through two main phases. The tectonic changes during the Alpine Orogeny that started 66 Ma ago and some earlier Jurassic activity, caused a compressive regime and thus produced a lot of pressure that caused folding on different scales and the continuing orogenic growth. Deformation occurred also after the collision. The orogenic basement can be described by inherited folded formations over a granitic basement.

 By Sarah Weick, researcher at the Georg August University in Göttingen.

 

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: Mountains, rivers and agriculture

This week’s Imaggeo on Mondays image blends a range of geoscience disciplines. The post, by Irene Marzolff, a researcher at Johann Wolfgang Goethe-Universitaet, explores how the mountains, rivers and soils of the High Atlas in Morocco are intrinsically linked to the agriculture of the region.

High Atlas landscape. Credit: Irene Marzolff (distributed via imaggeo.egu.eu)

High Atlas landscape. Credit: Irene Marzolff (distributed via imaggeo.egu.eu)

The image was taken in the southern slopes of the Western High Atlas, north of the city of Taroudannt. The snow of these mountains, which in April is still prevailing on the highest ranges in the background of the photo, is a significant water resource for the region. The high interannual variability of precipitation and its changing patterns associated to climate change present a serious challenge for natural environment and for the sustainable use of water as a resource in agriculture and tourism, the two major economic sectors in the area.

A characteristic open cover of Argan trees (Argania spinosa) can be seen on the lower mountain slopes in the middle distance of the photo: an endemic species with small, oil-rich fruits resembling olives that yield high-quality oil used in medicine, food and cosmetics. The species is a relic of the Tertiary (66 to 2.8 million years ago) but has been under threat from human exploitation for centuries, by excessive grazing, fire-wood cutting, charcoal making and changes to the groundwater table. The area is part of the UNESCO-MAB Biosphere Reserve “Arganeraie” committed to the preservation and sustainable use of the trees.

The river bed in the foreground is formed by fluvial processes typical for this high-mountain region, with highly variable seasonal discharges controlled both by rainfall and snowmelt. It will in the near future drain into the Sidi Abdellah Reservoir that is currently being constructed near Tamaloukt. This reservoir will add to the 10 already existing water storage lakes in the region of Souss Massa Drâa, which is in urgent need of additional water resources: The Souss Valley to the South of the High Atlas is one of Morocco’s most intensely farmed agricultural regions, with agro-industrial production of bananas, vegetables and citrus fruit. Much of this, including 90% of Morocco’s tomato production, is exported to the European market.

By Irene Marzolff, researcher at the Institut fuer Physische Geographie, Johann Wolfgang Goethe-Universitaet, Frankfurt.

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/.