GeoLog

imaggeo on mondays

Imaggeo on Mondays: A modern cliff hides ancient dunes

Imaggeo on Mondays: A modern cliff hides ancient dunes

Ancient sand dunes exposed off a cliff face on the shoreline of Nova Scotia at the Islands Provincial Park. The juxtaposition of the high angled strata and flat lying layers above revels the drastic change in climate in Nova Scotia’s history; from vast sand dunes to a calm lake system, and presently the western coastline of the Atlantic Ocean.

Description by Robert Wu, 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: 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: Cumulonimbus, king of clouds

Imaggeo on Mondays: Cumulonimbus, king of clouds

This wonderful mature thunderstorm cell was observed near the German Aerospace Center (DLR) Oberpfaffenhofen. A distinct anvil can be seen in the background meanwhile a new storm cell is growing in the foreground of the cumulonimbus structure. Mature storm cells like this are common in Southern Germany during the summer season. Strong heat, enough moisture, and a labile stratification of the atmosphere enables the development of this exciting weather phenomenon.

Description by Martin Köhler, 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/.