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Imaggeo on Mondays: Exploring the East African Rift

10 Mar

This week’s Imaggeo on Mondays is brought to you by Alexis Merlaud, an atmospheric scientist from the Belgian Institute for Space Aeronomy. While the wonders of the African atmosphere feature in his photography, the East African Rift has a much bigger tale to tell. Drawing from all aspects of geoscience Alexis shares its story…

Kilimanjaro from Mount Meru. (Credit: Alexis Merlaud, distributed via imaggeo.egu.eu)

Kilimanjaro from Mount Meru. (Credit: Alexis Merlaud, distributed via imaggeo.egu.eu)

This picture shows Kilimanjaro, Africa’s highest mountain, at sunrise. It was taken from Socialist Peak, which marks the top of Mount Meru, some 70 km to the southwest. Both mountains are located in Tanzania and are among the largest stratovolcanoes of the East African Rift Zone. Unlike Kilimanjaro, Meru is active and its most recent eruption occurred in 1910.

Stratovolcanoes, also called composite cones, are built-up by alternating layers of lava flows, pyroclastic rocks, and volcanic ash. During a large eruption, huge quantities of ash and sulphur dioxide can reach the stratosphere, where they can affect the climate for several years, as did the eruptions of Krakatau in 1883 and Pinatubo in 1991. Sulphur dioxide is converted to sulphuric acid droplets, which spread with the ashes throughout the stratosphere. These aerosols screen some of the sunlight, decreasing the average surface temperature by about one degree. The temperature in the stratosphere simultaneously rises by a few degrees, due to the enhanced absorption of sunlight by aerosols.

There is a difference in the tectonic processes associated with these South East Asian volcanoes and the East African Rift: the former are located above a subduction zone while the rift is a divergent boundary.  An example of large volcanic eruption in a divergent zone is the Laki (Iceland) eruption in 1783, which yielded severe meteorological conditions and reduced harvests for several years in Europe. This eruption may have also helped trigger the French Revolution in 1789.

Plate tectonics in East Africa created Kilimajaro and have also played a role in early human evolution, by shaping the local landscape and the long-term climate, thus modifying the environment of our ancestors. East Africa is the area in the world where most of the hominid fossils have been discovered, including Homo sapiens – the oldest fossil record is 200,000 years old and started to move out from Africa 100,000 years ago!

A final thanks: thanks Cristina Brailescu for help climbing Meru and Emmanuel Dekemper for support on editing the picture. 

By Alexis Merlaud, Belgian Institute for Space Aeronomy

Imaggeo is the EGU’s open access geosciences image repository. Photos uploaded to Imaggeo can be used by scientists, the press and the public provided the original author is credited. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. You can submit your photos here.

Geoscience under the tree

18 Dec

In a festive-themed post, EGU Media and Communications Manager Bárbara Ferreira selects a plethora of geoscience-inspired Christmas presents, which you could give to your favourite researcher. Please note that, with the exception of the last one, the items listed below are not necessarily recommended or endorsed by the EGU.

For me Christmas is more about eating large amounts of food and celebrating with family and friends than it is about giving and receiving presents. But I am guessing many of the readers of this blog are still scratching their heads thinking what gifts to get to the geoscientists in their families, to their Earth or space science researcher friends or, why not, themselves. This, and the fact that Paleoseismicity posted about some beautiful geology shoes a few days ago, is why I’ve set out to discover the best geoscience-inspired gift items out there.

Compiling this list ended up being easier than I thought because a few people, such as Georneys’ Evelyn Mervine and Agile’s Matt Hall have written similar blog posts in the past. And also because I discovered that Etsy – the e-commerce website for all things handmade or vintage – has an impressive collection of geoscience-y items. So, brace yourselves for a link-rich post!

Solid Earth

I’ll start with a present idea for our crafty readers: if you are into knitting, or know someone who is, this book filled with knitted-dinosaur patterns might be for you. If you’re not crafty, you may prefer to gift this triceratops cup or a pair of agate bookends, or even this t-shirt with a different take on the Earth’s internal structure. The geomorphologist in your life might like this antique map illustrating the geomorphology of the Alpine region or this simple yet beautiful travel journal.

If, instead, volcanology is your thing, then you might like this awesome volcano woolly hat – and if you are looking for a gift for a little one, this wooden volcano stacker could be your choice. For soil scientists, Etsy has a collection of beautifully illustrated soil postcards, while tectonic scientists and seismologists, may find this t-shirt funny. This science kit would suit a young fan of rocks and minerals, while this tie with crystalline formations would be more appropriate for a grown up.

Volcano hat by MariaBjork

Volcano hat by MariaBjork

Soft Earth

Moving on to soft-Earth disciplines, atmospheric scientists might like this wonderful screen print of different types of clouds, or this original necklace representing the various layers of the Earth’s atmosphere. And there’s this rather neat calendar of the sky and sea, which may also please ocean scientists. These researchers might also like an ocean tide ceramic pot or a 19th century map of the Atlantic Ocean.

Budding hydrologists, on the other hand, may be fascinated by this hydropower kit, while older ones will likely appreciate this antique engraving of water engineering. On the topic of antiques, the climate scientist in your life may like this climate map of Europe or this beautifully illustrated book to teach kids about climate. When gifting biogeoscientists, you can’t go wrong with this fantastic diatoms t-shirt (available for men and women) or these seaweed magnets.

Diatoms t-shirt by vortextradingcompany

Diatoms t-shirt by vortextradingcompany

Space and planetary science

Moving up into the upper atmosphere, your favourite solar-terrestrial scientist might like to receive this rather cute card of aurora in the Arctic or, for something a bit different, this pair of Northern Lights leggings! Going further up into space, the Earth’s magnetosphere finds its way into this totebag/backpack while the solar corona is the star of this antique print.

Planetary scientists also have plenty to choose from, with a variety of art decals and solar system charts available on Etsy. There is even a seller who builds jewellery with photos from NASA missions, such as this Mars Curiosity Rover pendant. Budding space and planetary scientists will likely be happy with this space exploration kit from National Geographic.

Interdisciplinary areas

Moving on to the more interdisciplinary areas of the EGU, I couldn’t help but mention Slow Factory, who produce stunning (but expensive!) clothing items from satellite images: the Terra MODIS Greenland dress and this silk square with an image of phytoplankton from the Bay of Biscay are two of the highlights. For something a bit more affordable, you could gift this top to bottom poster from Our Amazing Planet (sadly, the original interactive infographic can’t be put up on the wall) or this carbon cycle t-shirt. If you are feeling crafty, you can get LEGOs to build this rather incredible LEGO globe. Energy, resources and the environment enthusiasts have plenty to choose from, from a sustainable Earth lab or a solar-powered night light to a pair of windmill earings or a wind-energy decal. If great waves are more your thing, you may be interested in this tsunami top or, if landslides are your natural-hazard of choice, in this interesting pendant.

If you, like me, prefer to give and receive an experience as a gift, then why not offer a geoscientific trip? Though I haven’t been on a trip of this kind myself, I found a few companies that organise geo-themed excursions, such as this one in Italy, this one in Iceland or this one for trips further afield.

Finally, I couldn’t finish this blog post without suggesting the best present of them all (OK, I’m biased!). This Christmas, why not gift EGU memberships to the Earth, planetary and space scientists in your life? It is very affordable and researchers will likely appreciate the discounted registration rate members receive to the EGU General Assembly!

By Bárbara Ferreira, EGU Media and Communications Manager

Imaggeo on Mondays: All kinds of exposure

2 Dec

This photo was taken by Grant Wilson at Arches National Park, Utah, USA. The park is home to more than 2,000 sandstone arches, exposed by years of weathering and the removal of softer rock. They are part of the Entrada Sandstone formation, which was deposited during the Jurassic. “The arches form as ice accumulated in fissures expands and breaks the rock forming fins. Wind and water eroded the fins, removing the less resistant material to form the arches,” Wilson explains.

“Star trails at arches” by Grant Wilson, distributed by the EGU under a Creative Commons licence.

“Star trails at arches” by Grant Wilson, distributed by the EGU under a Creative Commons licence.

The arch in this photo is called Broken Arch because it has a crack running through its apex. The arch itself is not the only exciting feature in this photo though. It was taken at night – and those streaks in the sky are stars. But if the photo wasn’t taken during the day, how is it so bright?

Exposure. Not rock exposure, but the time taken to take a photo – this image was captured with a 3 hour-long exposure, letting a lot of light into the camera. This also means we can see the stars tracking across the sky: “During this time the Earth rotates approximately 45 degrees, forming the star trails in the photo. At the time the moon was almost full, which lit up the arch allowing it to be seen in the middle of the night,” explains Wilson.

For more on the formation of Utah’s sandstone arches, see this short animation, which takes you from the formation of the Rocky Mountains some 300 million years ago, through to the final steps that expose the arches that stand there today:

Imaggeo is the EGU’s open access geosciences image repository. A new and improved Imaggeo site will be launching soon, so you will be able to peruse an even better database of visually stunning geoscience images. Photos uploaded to Imaggeo can be used by scientists, the press and the public provided the original author is credited. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. You can submit your photos here.

Imaggeo on Mondays: Great faults and faultless geotourism

23 Sep

Road cuttings provide a great window into the wonders of what’s beneath the Earth’s surface. In this week’s Imaggeo on Mondays Bahram Sadry takes us through a beautiful fault between Tabriz and Tehran, Iran…

“Road cutting” by Bahram Sadry. Distributed by the EGU under a Creative Commons licence.

“Road cutting” by Bahram Sadry. Distributed by the EGU under a Creative Commons licence.

These incredible rock outcroppings along Zanjan-Tabriz highway (the northwest of Iran), are unlike any other outcrop in the world. They are a group of faults and fractures, brecciation and graben that form a part of Iran’s Pliocene-Pleistocene formations. And the diversity of colours in the layers of marls, clays and limestones, sometimes together with gypsum too, are very important for their scientific and educational values, as it is rare you come across such a great textbook example in the field!

This picture shows a normal fault and graben structure. This image was taken as part of a personal project investigating the changes of this outcrop in roadside, through weathering and eroding processes, due to the lack of geo-conservation measures.

Indeed, three years ago, taking inspiration from ecologists, I experimented with using Fixed-point photography in geo-conservation studies in order to monitor the visible changes to the outcrop caused by weathering. Regular travel between Tabriz and Tehran allows me to take repeated photos from this wonderful site.

Normal faults with depressed graben and elevated horst. A graben is produced when two parallel faults cause a blog of land to be depressed relative to the surrounding landscape, as you see in this diagram and in Sadry’s photo. (Credit: Wikimedia Commons user Gregors).

Normal faults with depressed graben and elevated horst. A graben is produced when two parallel faults cause a block of land to be depressed relative to the surrounding landscape, as you see in this diagram and the photo above. (Credit: Wikimedia Commons user Gregors).

By Bahram N Sadry, The Science and Culture University, Tehran

Bahram Sadry is a lecturer in geotourism and shares his experience of tourism& geology with the wider world on his Geotourism blog.

Imaggeo is the EGU’s open access geosciences image repository. A new and improved Imaggeo site will be launching soon, so you will be able to peruse an even better database of visually stunning geoscience images. Photos uploaded to Imaggeo can be used by scientists, the press and the public provided the original author is credited. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. You can submit your photos here.

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