GeoLog

Geomorphology

Imaggeo on Mondays: Mesopotamia, the ancient land between rivers

Mesopotamia, an area rich in history and considered as the cradle of civilisation, with the first populations establishing themselves in the region some 6000 years ago,lies between two great rivers: the Euphrates and the Tigris. The ancient territory spans areas of modern-day Iraq, Kuwait, the northeastern section of Syria and small sections of southeastern Turkey and southwestern Iran.

The history of Mesopotamia is intrinsically linked to the great rivers which define it. From changes of the river themselves (autogenic), through to non-living environmental factors (known as allogenic) and human activities, the rivers respond to a wide range of processes by changing their courses and forming new waterways.

However, keeping track of the river’s changing paths during their long histories can be tricky. Based on a common assumption made by archaeological studies of the Mesopotamian floodplain, where periods of activity of a river channel are considered to be closely linked to the ages of archaeological settlements, Jaafar H. Jotheri, (a PhD researcher at the University of Durham, UK), was able to study the history of the two rivers.

Most of the identified ancient settlements in the region are thought to have been established near active channels. “Therefore, the existence of settlements in certain areas is a good indication of the probability of the existence of a river close to the site and vice versa,” explains Jaafar. “Not only that, the ages of a settlement can give a suggested age during which a particular river channel was active,” he adds.

Cuneiform script, a style of writing which involved pressing a stylus into soft clay tablets and making indentations representing word-signs, was widely used in ancient Mesopotamia. A number of middle to late Holocene cuneiform tablets make direct reference to rivers. They often record instances in which settlers interacted with the rivers: the digging of new irrigation channels, the annual cleaning of a river or using the river to transport goods from one city to another.

“These texts are useful to determine the locations and period of existence of rivers, particularly when some texts refer to identified sites,” explains Jaafar.

Using this information, Jaafar has been able to identify and map three main courses of the Tigris, during three different time periods. These are, from oldest to the youngest: the Pleistocene course, the Holocene course and the modern course, as are seen in this week’s Imaggeo on Monday’s image.

Sumerian Cuneiform on a clay tablet. From Shuruppak or Abu Salabikh, Iraq, circa 2,500 BCE. British Museum, London. Credit: Gavin.collins, distributed via Wikimedia Commons.

Sumerian Cuneiform on a clay tablet. From Shuruppak or Abu Salabikh, Iraq, circa 2,500 BCE. British Museum, London. Credit: Gavin.collins, distributed via Wikimedia Commons.

No archaeological sites were found associated with the Pleistocene course, compared to the Holocene course, with which many archaeological sites are associated (dated from ~ 4000BC to 1200 AD).

“We have historical texts that suggest that the Holocene Tigris channel was abandoned and relocated to form the new modern course after 1258 AD, in a process known as avulsion” says Jaffar,  “there is also an indication that human activity might have been a trigger for the avulsion,” he adds.

The historical text indicate that farmers broke the banks of the Holocene aged channel of the river Tigris, digging irrigation canals to water low elevation farms.  The newly excavated channel (or canal) became the main waterway.
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/.

The EGU Network blogs are looking for guest contributions

Are you a budding science writer, or want to try your hand at science communication? You might just be the person for our EGU network bloggers! A number of our network blogs would like to give their pages a bit of a boost and are seeking guest bloggers to contribute new, informative and engaging posts on an ad hoc basis.

If you’ve recently been thinking about trying your hand at blogging, but aren’t sure if it’s for you or simply have a great story or research that you’d like to see ‘in print’, why not give guest blogging a try? Read on to find out which blogs are looking for contributions.

Four Degrees

4degreesWritten by Flo Bullough and Marion Ferrat , Four Degrees, looks at environmental geoscience issues from a science for policy perspective. Environmental geochemistry, climate change, policy and sustainability are brought together in this blog and explored at the interface between science and society.

Flo and Marion are looking for guest contributions, but would also be happy to welcome a more regular blogger to their team. So if you are interested in geoscience and policy and are looking for the opportunity to get into some regular science writing, fill out this form and Flo and Marion will be in touch soon!

Geology for Global Development (GfGD)

GfGDGfGD is a UK-based organisation, working to support young geologists to make an effective contribution to international development. The network blog is a place for the organisation to share articles, discussions, photographs and news about the role of geology within sustainable development and the fight against global poverty

Blog editor, and founder of the organisation, Joel Gill, has his hands full running the blog, the organisation and completing his PhD. As a result, the blog is particularly looking for guest contributions which explore the principles of international development and how the earth sciences can make a difference. Take a look at the blog for some inspiration and pitch your ideas to Joel using this form.

Geology Jenga

JengaA broad range of topics find their way into the posts of Geology Jenga, with authors Dan Schillereff and Laura Roberts Artal writing about all things science communication, their careers as budding academics, as well as the science behind geophysics and geomorphology.

However, since finishing their PhDs, the demands of their 9 to 5 jobs mean that Dan and Laura have less time to write and would welcome guest contributions on any of the topics above. If you’d like to contribute to the blog, why not get in touch with them using this form?

GeoSphere

GeoSphereThe term geosphere is an all-encompassing word that incorporates just about every aspect of the earth sciences. This means that topics ranging from geophysics to geochemistry to geobiology are part of the geosphere. The blog Geosphere honours its namesake by covering any and every topic in the geosciences. However, with blog author, Matt Herod’s research interests in geochemistry and hydrogeology you’ll likely find more posts on these topics.

Matt aims to make science clear for anyone that should stumble upon the geosciences and enhance awareness of the geosphere. If these goals resonate with you, then you writing for the Geosphere blog might just be the thing for you. Why not get in touch with Matt using this form?

Polluting the Internet

PollutingWill Morgan, an atmospheric sciences researcher from the University of Manchester, blogs at Polluting the Internet. Focusing on tiny particles suspended in our atmosphere, called aerosols, which can build up and pollute our skies. In the blog, Will explores current research in aerosol science, as well as his fieldwork exploits in pursuit of these tiny particles.

If this is your area of research too and you’d like to contribute a guest blog post on the subject, why not give it a go! You can get in touch with Will by filling out this form.

Green Tea and Velociraptors

GreenWhilst swamped by the writing of the thesis, Jon welcomes guest contributions to his blog too. Covering the subject of palaeontology as well as regularly writing about science communication and the open science movement, the blog has a diverse readership and offers a great platform for anyone how has something to say about these topics. Get in touch with Jon using this form.

The network blogs cover a range of topics in the Earth, planetary and space sciences, with the aim to foster a diverse community of geoscientist bloggers. If you’d like to submit a guest blog post, please fill out the forms available above. For general guest blogging guidelines, please refer to the submit a post page on the EGU official blog GeoLog.

Imaggeo on Mondays: Mountains, rivers and agriculture

This week’s Imaggeo on Mondays image blends a range of geoscience disciplines. The post, by Irene Marzolff, a researcher at Johann Wolfgang Goethe-Universitaet, explores how the mountains, rivers and soils of the High Atlas in Morocco are intrinsically linked to the agriculture of the region.

High Atlas landscape. Credit: Irene Marzolff (distributed via imaggeo.egu.eu)

High Atlas landscape. Credit: Irene Marzolff (distributed via imaggeo.egu.eu)

The image was taken in the southern slopes of the Western High Atlas, north of the city of Taroudannt. The snow of these mountains, which in April is still prevailing on the highest ranges in the background of the photo, is a significant water resource for the region. The high interannual variability of precipitation and its changing patterns associated to climate change present a serious challenge for natural environment and for the sustainable use of water as a resource in agriculture and tourism, the two major economic sectors in the area.

A characteristic open cover of Argan trees (Argania spinosa) can be seen on the lower mountain slopes in the middle distance of the photo: an endemic species with small, oil-rich fruits resembling olives that yield high-quality oil used in medicine, food and cosmetics. The species is a relic of the Tertiary (66 to 2.8 million years ago) but has been under threat from human exploitation for centuries, by excessive grazing, fire-wood cutting, charcoal making and changes to the groundwater table. The area is part of the UNESCO-MAB Biosphere Reserve “Arganeraie” committed to the preservation and sustainable use of the trees.

The river bed in the foreground is formed by fluvial processes typical for this high-mountain region, with highly variable seasonal discharges controlled both by rainfall and snowmelt. It will in the near future drain into the Sidi Abdellah Reservoir that is currently being constructed near Tamaloukt. This reservoir will add to the 10 already existing water storage lakes in the region of Souss Massa Drâa, which is in urgent need of additional water resources: The Souss Valley to the South of the High Atlas is one of Morocco’s most intensely farmed agricultural regions, with agro-industrial production of bananas, vegetables and citrus fruit. Much of this, including 90% of Morocco’s tomato production, is exported to the European market.

By Irene Marzolff, researcher at the Institut fuer Physische Geographie, Johann Wolfgang Goethe-Universitaet, Frankfurt.

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 place where water runs through rocks

Imaggeo on Mondays: The place where water runs through rocks

Antelope Canyon, located in Arizona, USA, was formed by erosion of the Navajo Sandstone, primarily due to flash flooding and secondarily due to other sub-aerial processes (think of physical weathering processes such as freeze-thaw weathering exfoliation and salt crystallisation). Rainwater runs into the extensive basin above the slot canyon sections, picking up speed and sand as it rushes into the narrow passageways. Over time the passageways are eroded away, making the corridors deeper and smoothing hard edges in such a way as to form characteristic ‘flowing’ shapes in the rock.

The Navajo Sandstone was deposited in an aeolian (wind-blown) environment composed of large sand dunes: imagine a sea of sand, or an erg, as it is known scientifically, not dissimilar to the present Sarah desert landscape. The exact age of the Navajo Sandstone is controversial, with dated ages ranging from Triassic to early Jurassic, spanning a time period between 250 million years ago to approximately 175 million years ago. The difficulty in determining the exact age of the unit lies in its lack of age diagnostic fossils. The Navajo Sandstone is not alone in this quandary, dating is a common problem in aeolian sediments.

“The picture was taken during a three week Southwest USA road trip in summer 2012. One of the highlights was the visit to Antelope slot canyon, which is located on Navajo land east of Page, Arizona. The Navajo name for Upper Antelope Canyon is Tsé bighánílíní, which means the place where water runs through rocks,” explains Frederik Tack, an atmospheric scientist from the Belgian Institute for Space Aeronomy and author of today’s Imaggeo on Monday’s photograph.

The erosive processes which form the canyon are still ongoing. There is an elevated risk of flash floods, meaning the canyon can only be visited as part of guide tours.

“The canyon was actually quite crowded which made taking this picture challenging, especially as I wanted to capture the peace and solitude of the landscape,” describes Tack.

The effort was worth it: Waved rocks of Antelope slot canyon was one of the EGU’s 2015 Photo Contest finalists!

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/.

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