GeoLog

GeoLog

Imaggeo on Mondays: Corno Grande, tallest peak of the Apennines

Imaggeo on Mondays: Corno Grande, tallest peak of the Apennines

In the middle of the Apennines lays the Gran Sasso d’Italia mountain chain, a picturesque collection of mountains situated in the heart of Italy.

Featured here is one of the chain’s peaks, called the Corno Grande, meaning ‘Big Horn,’ coloured with a faint reddish light of a late-winter sunset. Sitting at 2,912 metres, this summit is easily the highest mountain in the Apennines.

The areas surrounding Corno Grande is enclosed in the Gran Sasso e Monti della Laga National Park, located in the hinterland of Italy’s Abruzzo region. The park, established in 1991, encompasses 2,015 square kilometres, making it one of the largest natural reserves in Europe.

Moreover, from an ecological standpoint, the region is one of the most biologically diverse areas in Europe, with more than 2,000 plant species, many of which can only be found in the park, and many rare animals.

The landscape that surrounds Corno Grande still shows traces of glacial erosion from the Quaternary Period, which began 2.6 million years ago. The region’s smooth highlands and U-shaped valleys are engravings of the slow glacial processes that occurred on these lands. The Corno Grande is even still host to a glacier today, as you can find the Calderone glacier, Western Europe’s southernmost glacier, beneath the mountain’s peak.

Sketch of the geodynamic setting of the Gran Sasso (Credit: Cardello and Doglioni, 2015)

The Apennine Mountains were built by a paradoxical geologic process, sometimes referred to as ‘syn-orogenic extension,’ where thickened crust spreads out while, at the same time, a belt of Earth’s crust is compressed, forming a chain of mountains. In the case of the Apennines, compression took place east of the range while extension occurred to the west.

“This synchronous processes of such different motions in the convergent belts is still an issue that must be unraveled for a better understanding of the mountain ridge formation,” said Alex Righetti, a PhD student studying marine geology at the Faculty of Sciences of the University of Lisbon, in Portugal, who captured this shot.

By Olivia Trani, EGU Communications Officer and Alex Righetti, FCUL

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/.

Geosciences Column: The best spots to hunt for ancient ice cores

Geosciences Column: The best spots to hunt for ancient ice cores

Where in the world can you find some of Earth’s oldest ice? That is the question a team of French and US scientists aimed to answer. They recently identified spots in East Antarctica that likely have the right conditions to harbor ice that formed 1.5 million years ago. Scientists hope that obtaining and analysing an undisturbed sample of ice this old will give them clues about Earth’s ancient climate.

The team published their findings in The Cryosphere, an open access journal of the European Geosciences Union (EGU).

Why study ancient ice?

When snow falls and covers an ice sheet, it forms a fluffy airy layer of frozen mass. Over time, this snowy layer is compacted into solid ice under the weight of new snowfall, trapping pockets of air, like amber trapping prehistoric insects. For today’s scientists, these air bubbles, some sealed off thousands to millions of years ago, are snapshots of what the Earth’s atmosphere looked like at the time these pockets were locked in ice. Researchers can tap into these bubbles to understand how the proportion of greenhouse gases in our atmosphere have changed throughout time.

As of now, the oldest ice archive available to scientists only goes back 800,000 years, according to the authors of the study. While pretty ancient, this ice record missed out on some major climate events in Earth’s recent history. Scientists are particularly interested in studying the time between 1.2 million years ago and 900,000 years ago, a period scientifically referred to as the mid-Pleistocene transition.

In the last few million years leading up to this transition, the Earth’s climate would experience a period of variation, from cold glacial periods to warmer periods, every 40,000 years. However, after the mid-Pleistocene transition, Earth’s climate cycle lengthened in time, with each period of variation occurring every 100,000 years.  

Currently, there isn’t a scientific consensus on the origin of this transition or what factors were involved. By examining old ice samples and studying the composition of the atmospheric gases present throughout this transition, scientist hope to paint a clearer picture of this influential time. “Locating a future 1.5 [million-year]-old ice drill site was identified as one of the main goals of the ice-core community,” wrote the authors of the study.  

The quest for old ice

Finding ice older than 800,000 years is difficult since the Earth’s deepest, oldest ice are the most at risk of melting due to the planet’s internal heat. Places where an ice sheet’s layers are very thick have an even greater risk of melting.

Mesh, bedrock dataset (Fretwell et al., 2013; Young et al., 2017) and basal melt rate (Passalacqua et al., 2017) used for the simulation. Credit: O. Passalacqua et al. 2018.

“If the ice thickness is too high the old ice at the bottom is getting so warm by geothermal heating that it is melted away,” said Hubertus Fischer, a climate physics researcher from the University of Bern in Switzerland not involved in the study, in an earlier EGU press release.

Last summer, a team of researchers from Princeton University announced that they had unearthed an ice core that dates back 2.7 million years, but the sample’s layers of ice aren’t in chronological order, with ice less than 800,000 years old intermingling with the older frozen strata. Rather than presenting a seamless record of Earth’s climate history, the core can only offer ‘climate snapshots.’

Finding the best of the rest

The authors of the recent The Cryosphere study used a series of criteria to guide their search for sites that likely could produce ice cores that are both old and undisturbed. They established that potential sites should of course contain ice as old as 1.5 million years, but also have a high enough resolution for scientists to study frequent changes in Earth’s climate.

Additionally, the researchers established that sites should not be prone to folding or wrinkling, as these kinds of disturbances can interfere with the order of ice layers.

Lastly, they noted that the bedrock on which the ice sheet sits should be higher than any nearby subglacial lakes, since the lake water could increase the risk of ice melt.

Magenta boxes A, B and C correspond to areas that could be considered as our best oldest-ice targets. Colored points locate possible drill sites. Credit: O. Passalacqua et al. 2018.

 

Using these criteria, the researchers evaluated one region of East Antarctica, the Dome C summit, which scientists in the past have considered a good candidate site for finding old ice. They ran three-dimensional ice flow simulations to locate parts of the region that are the most likely to contain ancient ice, based on their established parameters.

By narrowing down the list of eligible sites, the researchers were able to pinpoint regions just a few square kilometres in size where intact 1.5 million-year-old ice are very likely to be found, according to their models. Their results revealed that some promising areas are situated a little less than 40 kilometres southwest of the Dome C summit.

The researchers hope their new findings will bring scientists one step closer towards finding Earth’s ancient ice.

By Olivia Trani, EGU Communications Officer

Imaggeo on Mondays: Namibia’s mysterious fairy circles

Imaggeo on Mondays: Namibia’s mysterious fairy circles

The grassy Namibian desert is pock-marked with millions of circular patches of bare earth just like these shown in the picture between linear dunes.

Viewed from a balloon, they make the ground look like a moonscape. Commonly known as fairy circles, the patches range from two to 12 metres across and appear in a 2000 kilometre strip that stretches from Angola to South Africa.

For many decades, the fairy circles extending uniformly over vast areas in the landscape, have puzzled laymen and scientists alike. They are subject to a lively debate and contrary hypotheses on their origin exist. Some researchers claim fairy circles were caused by termites, others propose they are the result of vegetation self-organization.

Description by Hezi Yizhaq, 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/.

Shape the EGU 2019 scientific programme: The call for sessions is open!

Shape the EGU 2019 scientific programme: The call for sessions is open!

Do you enjoy the EGU’s annual General Assembly but wish you could play a more active role in shaping the scientific programme? Now is your chance!

From today, until 6 Sep 2018, you can suggest:

  • Sessions (with conveners and description),
  • Short Courses, or;
  • Modifications to the existing skeleton programme sessions

Plus from now until 18 January 2019, you can propose townhall meetings. It’s important to note that, for this year’s General Assembly, session proposals for Union Symposia and Great Debates are due by 15 August 2018.

Explore the EGU 2019 Programme Groups (PGs) to get a feel for the already proposed sessions and to decide which PG would be the best fit for your session. When proposing a session, it’s strongly encouraged to form convener teams that reflect diversity in countries/institutes, gender and career level. A minimum of two conveners  and a maximum of five conveners per session is generally desirable.

Does your idea for a session fall under the remit of two (or more) PGs? Co-organization is possible and encouraged between groups! Put your session proposal into one PG, and you will be able to choose other PGs that you believe should be approached for co-organization.

EGU introduced the programme group Interdisciplinary Events (IE) in 2016, which has now been renamed to Inter- and Transdisciplinary Sessions (ITS). ITS looks for links between disciplines in a coordinated and coherent effort, trying to create new approaches that would not be possible if handled separately. ITS has four sub-programme groups that highlight new themes each year. If you plan to propose an Inter- and Transdisciplinary Session, please submit your proposal in programme group ITS and indicate relevant other programme groups in the session description or comment box. For ITS sessions we kindly ask to identify another programme group that becomes the scientific leader of the event. Accepted ITS sessions will be part of the session programme of the scientific leader in addition to the ITS programme.

The PG officers are on-hand to answer questions about the appropriateness of a specific session topic, so don’t hesitate to contact them if you have queries! You can also find more information about the call for sessions (and the organisation of the scientific programme in general) on the EGU 2019 website.

The EGU’s 2019 General Assembly, takes place in Vienna from 7 to 12 April, 2018. For more news about the upcoming General Assembly, you can also follow the offical hashtag, #EGU19, on our social media channels.