GeoLog

Stratigraphy, Sedimentology and Palaeontology

Imaggeo on Mondays: how short-term storms can impact our landscapes

Imaggeo on Mondays: how short-term storms can impact our landscapes

In the Sierra de Aconquija, a mountain range in the southern Central Andes of Argentina, strong storms often come and go at a moment’s notice, but they can have a long-lasting impact on the Earth’s surface.

The thunderstorm cell featured in this photo formed in less than half an hour, giving all those nearby only a few minutes to take cover. Mitch D’Arcy, a geomorphologist and postdoctoral researcher at the University of Potsdam and the GFZ German Research Centre for Geosciences, had the opportunity to witness this storm (and snap this picture!) while carrying out field work in the area.

“It was a spectacular experience, pouring heavy rain onto a very localised part of the mountain range, but it was also a hazard because the storm was quickly moving towards us with a lot of lightning. Without any trees around, we were likely targets for lightning strikes!” said D’Arcy. Luckily, he and his colleagues were able to find shelter in their truck while the huge downpour passed over them.

These kinds of thunderstorms are short-lived, but have intense precipitation rates. In this case, the temperature dropped by 14 degrees Celsius, and the storm was accompanied by heavy hail and lightning. And while these natural hazards are transient, they can have a long-term impact on the region’s landscape. Severe storms are capable of triggering landslides and floods and can relocate large amounts of sediment and debris in a short period of time.

D’Arcy is part of an international research programme called StRATEGy (Surface processes, Tectonics and Georesources: The Andean foreland basin of Argentina), which looks into how past and present climate change makes a mark on the terrain of the Argentine Andes, among other topics.

This research is essential for understanding and predicting how human-caused climate change will alter weather patterns and impact surface processes (such as how quickly sediments are eroded and transported across landscapes), according to D’Arcy. Having a better understanding of these surface processes and their sensitivity to the climate could help scientists better inform the public about how to prepare for natural hazards, such as flooding, erosion and landslides.

D’Arcy notes that it’s also important to assess how climate and weather trends will impact the sedimentary record, since it is one of the only physical records that scientists can use to examine how the Earth’s surface has change through time.

“North-western Argentina is a fascinating place to study how climate change affects surface processes, because it has experienced pronounced and abrupt changes in hydroclimate through time,” said D’Arcy. Their research has found that even subtle changes in the region’s climate have produced large changes to the surface environment, impacting how rivers take shape and how sediments move.

For example, while the Sierra de Aconquija is a semi-arid environment today, more than 12,000 years ago it used to be much wetter as a result of global climate changes. In fact, back then the mountain range was covered in glaciers and many of the basins were filled with lakes.

“It’s really important that we understand how different landscapes function and how they react to changes in climate. When we look at places like the southern Central Andes in Argentina, we find that the landscape records interesting signatures of ancient climate changes in Earth’s past. However, one of the big questions we still don’t have a good answer to, is how important are these very intense but rare storms for shaping landscapes and creating the sedimentary record from the geological past,” said D’Arcy.

By Olivia Trani, EGU Communications Officer

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 salt mine carving into the Carpathians

Imaggeo on Mondays: The salt mine carving into the Carpathians

The image gives us a glimpse into the Slănic Salt Mine in central Romania, about 100 kilometres north of the capital city Bucharest. The region was actively mined for almost 30 years, from 1943 to 1970.

The Slănic Salt Mine is the largest salt mine in Europe, and the facility consists of 14 large chambers, each more than 50 metres high. The cavities of the mine, more than 200 metres deep, carve into the Southern Carpathian Mountains, offering a unique large-scale view into how the layers of rock beneath the Earth’s surface bend and fold. The structures featured in this image were stretched out over time as the Earth’s tectonic plates shifted, highlighting just how fluid our planet can be.

Compared to other rocks, the rock salts in this mine can change form and flow without much pressure and at relatively shallow depths. “This flow is however very slow, so that man-made cavities in salt mines deform very slowly and remain open for decades,” notes Janos Urai, a professor of structural geology, tectonics and geomechanics at RWTH Aachen University in Germany who snapped this image while visiting the mine in 2017. “We study this slow flow of salt in nature, to be able to improve predictions of the long-term evolution of nuclear waste repositories and abandoned salt caverns.

The mine is no longer used for resource extraction, but is now an active tourist destination (there are even playgrounds, pool tables and other recreational features).

By Olivia Trani, EGU Communications Officer

You can learn more about salt tectonics on the Tectonics and Structural Geology blog here:  Minds over Methods: Reconstruction of salt tectonic features

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: A slice of fossil life

Imaggeo on Mondays: A slice of fossil life

I am a petrographer at the University of Padova, Italy, studying the metamorphic rocks that form the deep Earth’s crust beneath our feet, and what happens when they get so hot to start to melt.

I’ve spent (enjoyed I should say) more than 30 years looking at rocks with an optical microscope. This simple, cheap tool, and more importantly, its skilled use, remain key ingredients for good research in petrology!

I’ve been taught by scientists, like Ron Vernon of Macquarie University in Australia, that a good micrograph is essential to document my research and strengthen my conclusions, and so I’ve always paid particular attention to the quality of photos. In the meanwhile, I have also developed a particular interest in photomicroscopy with an aesthetic purpose, realizing that the cocktail of rocks and polarized light has an extraordinary potential in the ‘sciart’ (Science-and-Art) field.

The digital revolution has marked a turning point in this activity, and 10 years ago I have started my micROCKScopica project to showcase to the public the beauty hidden in the small slices of rock that are thin sections.

When I find a photogenic rock I play with polarizers to get the desired combinations of color, and then I take a photograph. And people can enjoy the images, their colors and shapes, even without knowing the geological history behind them.

This is particularly true for this photograph: it is a thin section of a piece of dinosaur bone but I don’t know much about it (what bone, which dinosaur), only that it had been collected in Utah, in the United States. I received a small sample of the bone by Denise M. Harrison, a friend with whom I collaborated for a book on Lake Superior Agates. She is an award-winning lapidary (someone who cuts, polishes and engraves stones), and makes lovely cabochons with all sort of semiprecious, hard stones. I asked her for some leftovers to make some thin sections, because I wanted to see something new, possibly silicified (impregnated with silica during fossilization) because chalcedony – the very fine-grained variety of common quartz – may be extremely photogenic.

I had no idea of how a bone could look like under the microscope, and the first sight left me speechless! The porous structure, and the patterns of the radiating textures in the chalcedony fillings are extraordinary, and provide a wealth of possibilities for nice images.

In this shot, that I replicated in red and blue, a larger hole had been filled with a fine-grained quartz sand – the dark moon shape on top left – somehow interrupting the regular pattern of the bone tissue, that to someone may recall Australian Aboriginal artwork.

Curiously, this anatomically-related image made me quite popular among pathologists and other medical doctors, who find many analogies with their subjects of research. The ages of the specimens are some hundred million years apart, though…

By Bernardo Cesare, University of Padova, Italy

www.microckscopica.org

Editor’s note: The fossil sample featured in this photo was collected and distributed legally from Utah.

If you pre-register for the 2019 General Assembly (Vienna, 07–12 April), you can take part in our annual photo competition! From 15 January until 15 February, every participant pre-registered for the General Assembly can submit up three original photos and one moving image related to the Earth, planetary, and space sciences in competition for free registration to next year’s General Assembly!  These can include fantastic field photos, a stunning shot of your favourite thin section, what you’ve captured out on holiday or under the electron microscope – if it’s geoscientific, it fits the bill. Find out more about how to take part at http://imaggeo.egu.eu/photo-contest/information/.

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/.

Winners of the EGU Best Blog Posts of 2018 Competition

Winners of the EGU Best Blog Posts of 2018 Competition

There is no doubt that 2018 was packed full of exciting, insightful and informative blog posts. An impressive 382 posts were published across the EGU’s official blog, GeoLog, as well as the network and division blogs!

In December, to celebrate the excellent display of science writing across the network and division blogs, we launched the EGU Blogs competition. From a list of posts selected by our blog editors, we invited you, the EGU Blogs readers, to vote for your favourite post of 2018. We also invited EGU division blog editors and office staff to take part in a panel vote. After more than two weeks of voting, the winners are finally in!

Without further ado, we’d like to extend a big congratulations to the Geodynamics (GD) Division Blog, winner of the public vote, and the Geology for Global Development (GfGD) Blog, winner of the panel vote!

The GD division blog was crowned winner of this year’s public vote for their post on the Global Young Scientists Summit (GYSS) in Singapore! Follow blog contributor Luca Dal Zilio’s experience attending this gathering of over 250 PhD and postdoctoral fellows!

The GfGD blog snagged first place in the panel vote with their post: The Case Against Fieldwork – How can we internalise the carbon cost of fieldwork, as scientists who investigate the earth system? Read blog contributor Robert Emberson’s analysis and personal experience with the carbon footprint of working in the field!

All the posts entered into the competition are worthy of a read too, so head over to the poll and click on the post titles to learn about a variety of topics: from social media responses to geomagnetic activity, to exploring what artificial intelligence can do for climate science and watching socio-hydrology on Broadway.

If the start of a new year, with its inevitable resolutions, along with the range and breadth of posts across the EGU Blogs have inspired you to try your hand at a little science writing then remember all the EGU Blogs welcome (and encourage!) guest posts. Indeed, it is the variety of guest posts, in addition to regular features, which makes the blogs a great read! If you would like to contribute to any of the network, division blogs or GeoLog, please send a short paragraph detailing your idea to the EGU Communications Officer, Olivia Trani at networking@egu.eu.