GeoLog

Field Rucksack

Imaggeo on Mondays: A lava layer cake

Imaggeo on Mondays: A lava layer cake

Brekkuselslækur, a small river, carves its way across Iceland’s ancient volcanic landscape. At Hengifoss, Iceland’s third-highest waterfall, it tumbles fiercely down thick, dark layers of lavas erupted from volcanoes some 18 to 2.58 million years ago, during a period of geological time known as the Tertiary.

Eruptions are rarely continuous; during hiatuses in the extrusion of lavas, ash is able to settle atop the smoldering layers. If the pauses are long enough and the conditions just right (a warm and humid climate is needed) the ashes, through the addition of clay and iron minerals, slowly turn to soil . When new lavas are layered over the top of the ash-rich soils, a chemical reaction takes place between the iron trapped in the soil and the oxygen transported by the lavas, to form iron oxide. In essence, the soils rust and turn a distinctive red colour.

As the process is repeated time and time again, layers of alternating black lavas and red soils are built up to form a giant ‘mille feuilles’ cake.

In the summer months, tourists flock to this popular site. An unspoilt view of the 188m high torrent means an early morning hike to beat the crowds. For a bird’s eye view of Hengifoss, the adventurous can even scarmble to the cliff tops too.

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 Contest 2017!

The selection committee received over 300 photos for this year’s EGU Photo Contest, covering fields across the geosciences. Participants at the 2017 General Assembly have been voting for their favourites throughout the week  of the conference and there are three clear winners. Congratulations to 2017’s fantastic photographers!

Penitentes in the Andes by Christoph Schmidt (distributed by imaggeo.egu.eu). This photo was taken in the Bolivian Andes at an altitude of around 4400 m. The climatic conditions favour the formation of so-called penitents, i.e. long and pointed remains of a formerly comprehensive snow field.

Symbiosis of fire, ice and water by Michael Grund (distributed by imaggeo.egu.eu). This picture was taken at Storforsen, an impressive rapid in the Pite River in northern Sweden.

Movement of the ancient sand by Elizaveta Kovaleva (distributed by imaggeo.egu.eu). In the Zion National Park you can literally touch and see the dynamic of the ancient sand dunes.

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: Gole dell‘ Alcantara

Imaggeo on Mondays: Gole dell‘ Alcantara

On account of Mount Etna (Europe’s largest volcano), the island of Sicily is peppered with geological wonders. Starting with the summit craters of the volcano itself, right through to over 200 caves formed within lava tubes, the island is packed with volcanic sights.Chief among them is Gole dell ‘Alcantara, a system of gorges formed 8,000 years ago in the course of the river Alcantara in eastern Sicily.

The network of gorges have a maximum depth of 40 m and a width of up to 5 m. They are the result of intense, deep erosion,  of 300,000 year old basaltic rocks, by flowing water. The lavas were once thought to originate from the nearby Monte Moio; an unusual crater not linked to the main Etna volcanic plumbing system. More recent research, including detailed petrographic studies, points towards the craters of Monte Dolce, in the medium-low side of Etna, as being the source of the lavas exposed in the Gole dell ‘Alcantara.

As today’s featured image shows, the lavas exposed throughout the gorge walls are remarkable. Erupting in river waters meant that the lavas cooled faster than they would have done otherwise, giving rise to fractures which formed prismatic structures. Some are chaotic, but others are arranged horizontally (locally known as the woodpile), slightly arching (the harp) and in a radial configuration known as the rosette. The most common configuration is the ‘organ pile’ where vertical fractures form, up to 30m high.

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/.

What is in your field rucksack? Backpacking in the wilderness

When hiking to altitudes above 2000 m packing light is crucial! Credit: Alexa Van Eaton

When hiking to altitudes above 2000 m packing light is crucial! Credit: Alexa Van Eaton

Inspired by a post on Lifehacker on what your average geologist carries in their rucksack/backpack, we’ve put together a few blog posts showcasing what a range of our EGU members carry in their bags whilst in the field!

This bag belongs to: Alexa Van Eaton

Field Work location: Glacier Peak volcano, Washington, USA

Duration of field work: 12 days

What was the aim of the research?: Glacier Peak is an ice-clad stratovolcano in Washington State, USA. Even though it is the second most explosive volcano in the Cascade Range (behind Mount St. Helens), it is so remote that most people haven’t even heard of it. Unlike Mount St. Helens, Hood or Rainier, the volcano can’t be seen from any of the major cities in the Pacific Northwest. This summer, we spent 12 days backpacking through the Glacier Peak Wilderness area to investigate the volcano’s eruptive history.

Fuel is important during field work too! Credit: Alexa Van Eaton (click to enlarge)

Fuel is important during field work too! Credit: Alexa Van Eaton

One specific aim was to document the deposits from two large, explosive eruptions that occurred about 13.5 thousand years ago. These eruptions transported volcanic ash all the way out to the east coast of the USA, and likely beyond. But the detailed story of what really happened during those eruptions—and why they occurred in the first place—is best recorded in the thick deposits close to the volcano. Getting to these sites high on Glacier Peak meant backpacking to about 7,000 ft [over 2000 m ] elevation through dense forest.

Roughly half the time we would set up a base camp and coordinate day hikes for the mapping and stratigraphic work. Other times we would traverse with our gear to cover more ground. That made the backpack situation pretty crucial. During last year’s fieldwork my backpack was way too heavy (maybe ~40 pounds?), so this time I was committed to slimming it all down, without sacrificing the essentials (e.g., coffee and chocolate…). This year my base weight was ~8 pounds lighter, which made a huge difference.

The one item I couldn’t live without: Cold-weather down sleeping bag (rated to -16degC). A close runner-up would be my 1944 US Army entrenching shovel. It’s vintage and ridiculously heavy, but nothing does a better job of chopping climbing steps into steep tephra outcrops just when you need it.

USGS summer intern Kristin Beck enjoying the view of Glacier Peak volcano from 7,000 ft. elevation. Credit: Alexa Van Eaton

USGS summer intern Kristin Beck enjoying the view of Glacier Peak volcano from 7,000 ft. elevation. Credit: Alexa Van Eaton

 

If you’ve been on field work recently, or work in an industry that requires you to carry equipment, and would like the contents of your bag to feature on the blog, we’d love to hear from you. Please contact the EGU’s Communication Officer, Laura Roberts (networking@egu.eu)