GeoLog

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This guest post was contributed by a scientist, student or a professional in the Earth, planetary or space sciences. The EGU blogs welcome guest contributions, so if you've got a great idea for a post or fancy trying your hand at science communication, please contact the blog editor or the EGU Communications Officer Laura Roberts Artal to pitch your idea.

Imaggeo on Mondays: Tombstones Mountains

Imaggeo on Mondays: Tombstones Mountains

This week’s Imaggeo image is brought to you by one of our network bloggers, Matt Herod. Of the image, Matt said ” this particular one is one of my all time favourites. I have even blown it up and hung it on my wall at home,” and we couldn’t agree more; this Canadian landscape is breathtaking. Dive into this post and let Matt take you on a tour of the hydrology, archaeology and volcanic history of the Tombstone Mountain Range.

The Yukon Territory in the fall is a wonderful place and may be among the most beautiful on Earth. As the days shorten the colours become more vibrant and the grasses and shrubs transform. Combine this with the stark and rugged nature of the landscape and you have a potent combination that begs to be explored and photographed.

The subject of this photo is the Tombstone Mountain Range just north of Dawson City, a world heritage site famous for its gold rush, the Sourtoe Cocktail and the funnest casino I have ever been to. The Tombstones constitute the headwaters of the North Klondike River which flows at the base of the valley in the photo and eventually meets up with the larger Klondike River and then joins with the Yukon River at Dawson. Hydrologically the Tombstones mark a continental divide and the transition from southern flowing rivers to northern ones takes place nearby as the many of the rivers just slightly to the north feed into the Peel River and eventually the mighty Mackenzie. A colleague of mine recently concluded a project on the North Klondike measuring the groundwater discharge and chemistry of the river over several years to understand the water sources and the effect of permafrost on the local hydrology.

Indeed, at the base of the valley there is a groundwater discharge point that builds up every winter into a large, layered sheet of ice called and aufeis. As the warmer groundwater continues to discharge throughout the winter it freezes when it meets the cold air forming the aufeis. These structures are often seen at groundwater discharge points in the far north.

The Tombstones themselves, named after the really pointy mountain in the background, are geologically very interesting. Indeed, this relief was created by igneous intrusions during the Cretaceous period. More recently, alpine glaciations shaped the terrain giving rise to a suite of interesting geomorphological and permafrost structures.

The region also has a fascinating archeological heritage and is home to over 70 sites dating back ~8000 years to the Holocene period and some of the earliest human incursions into North America via the Bering land bridge.

This photo was taken in August 2012 on my way up the Dempster Highway. I was collecting water samples for iodine-129 analysis and stopped off in the Tombstone Territorial Park for a sample.

By Matt Herod, researcher at Department of Earth Sciences at the University of Ottawa in Ontario, Canada.

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 Oldest Eurypterid

Geosciences Column: The Oldest Eurypterid

The name of a newly found fossil of sea scorpion draws inspiration from ancient Greece warships and is a unique example of exceptional preservation, shedding light on the rich life of this bygone sea critter, explains David Marshall of Palaeocast fame. To learn more about the importance of giving new fossils names and what Pentecopterus decorahensis (as the new fossil is formally called) teaches us about a crucial time for biodiversification, read on!

It is considered best-practice that organisms, extinct or extant, be given a descriptive name. Triceratops, or ‘three horned-face’, is a perfect example of this. However scientists have often utilised some poetic license with this: Tyrannosaurus rex translates as ‘tyrant lizard king’, referring to its unrivalled size and ferocity, and Brontosaurus as ‘thunder lizard’, envisioning the noise produced by the placement of one of its gigantic legs. Recently the etymology of some names has become somewhat less poetically-descriptive and more, shall we say, ‘tabloid-newspaper-friendly’. The publication of names such as Dracorex hogwartsia, translating as ‘dragon king of Hogwarts’, do conjure images, even if it is done with a lot of artistic license. One animal with an equally abstract, but appropriate, name is described in BMC Evolutionary Biology today as Pentecopterus decorahensis.

Pentecopterus is a newly identified species of eurypterid, or ‘sea scorpion’. Eurypterids are an extinct group of chelicerates, the group containing the terrestrial arachnids (such as spiders and scorpions) and the aquatic ‘merostomes’ (represented today solely by the horseshoe crabs). The sea scorpions bear a close morphological resemblance to their namesakes, but perhaps may have been more closely related to horseshoe crabs. They were active predators or scavengers in the Paleozoic seas, between the Ordovician and Permian periods, approximately 460 – 250 million years ago. Some crawled along the ocean floor, whilst others were capable of limited swimming. Some reached incredible size, with the largest arthropod yet discovered, Jaekelopterus, estimated to have measured up to 2.5m.

Whilst most were quite small and generally unremarkable to look at, some eurypterids were truly the things of nightmares. Pentecopterus was a megalograptid: a particularly large and well-armed eurypterid family, typically measuring between 0.75 and 1.5m. Their appendages bore an array of inward-facing spikes, perfect for ambush, but without jaws, teeth or the sophisticated injection of enzymes, they (as with all eurypterids) would have simply shredded their prey into small enough pieces to eat. These were undoubtedly active predators, built as if solely for offence.

Results of the phylogenetic analysis plotted as an evolutionary tree. All of the branches of the tree leading to Pentecopterus must have occurred before we see our first Pentecopterus specimen (solid box). We can therefore infer ‘ghost ranges’ (dashed lines) for many eurypterid species and groups, where we believe they existed, but haven’t found fossils yet. Examination of rocks within the ghost ranges may yield new finds.

Results of the phylogenetic analysis plotted as an evolutionary tree. All of the branches of the tree leading to Pentecopterus must have occurred before we see our first Pentecopterus specimen (solid box). We can therefore infer ‘ghost ranges’ (dashed lines) for many eurypterid species and groups, where we believe they existed, but haven’t found fossils yet. Examination of rocks within the ghost ranges may yield new finds. Image credit: James C. Lamsdell et al / BMC Evolutionary Biology

Pentecopterus was discovered close to Decorah, Iowa, (hence the species name decorahensis) and is the oldest eurypterid yet described, hailing from the Darriwilian Stage of the Ordovician Period, some 467.3 – 458.4 million years old. This was a time of great change; the Ordovician biosphere underwent an explosion of species, form and ecology, in what is now dubbed the ‘Great Ordovician Biodiversification Event’. Organisms, previously confined to in and around the sea floor in the Cambrian period, began inhabiting the whole water column. Photosynthesising plankton took off (figuratively and literally) and the oceans were filled with new food webs based on this primary productivity. Sitting close to the top of the pile was Pentecopterus, a new kind of predator: large, armour-clad and armed to the teeth.

The genus name Pentecopterus is derived from marriage of the Greek words Πεντηκόντορος (Penteconter) with φτερός (–pterus, meaning wing) as the standard suffix for eurypterid genera. The Penteconter is a ship from the Archaic Period of Ancient Greece. This period saw the rapid expansion of the population of Greece, the formation of the city-state and founding of colonies. The Archaic period was a time of great social, political and economic change. This was primarily facilitated by the relationship the Ancient Greeks had with sea. But up until this time, there was little diversity in form of vessels; form did not necessarily follow function.

The Penteconter changed this. A vessel powered by 50 men (the name translating as fifty-oared), it was fast, manoeuvrable and built solely for aggression. It is considered to be the world’s first warship.

But far beyond the tabloid media coverage of ‘Oldest killer sea scorpion found’, and even my fondness for its poetical name, Pentecopterus is quite a remarkable specimen for our understanding of eurypterids.

Reconstruction: Scientific reconstruction of Pentecopterus. A, Dorsal view of a complete specimen. B, Genital segment. C, Ventral view of headshield. The semi-circular area is where the appendages would have inserted. D, Ventral view of prosoma with appendages in place. Scale 10cm.

Reconstruction: Scientific reconstruction of Pentecopterus. A, Dorsal view of a complete specimen. B, Genital segment. C, Ventral view of headshield. The semi-circular area is where the appendages would have inserted. D, Ventral view of prosoma with appendages in place. Scale 10cm. Image credit: James C. Lamsdell et al / BMC Evolutionary Biology

Despite most of the Pentecopterus specimens being disarticulated or fragmentary, with parts of the animal still yet to be discovered, there are enough pieces to put together a very good picture of its external anatomy. From the presence or absence of spines on certain parts of its appendages, this new species can clearly be assigned to the megalograptid family. For various anatomical reasons, the megalograptids have long been considered to be one of the most primitive groups of eurypterids, placed right at the base of the eurypterid ‘family tree’, with Pentecopterus as the oldest yet found supporting this theory. However, a phylogenetic analysis (a hypothesis of likely relationship based on numbers of shared anatomical characteristics) conducted on the eurypterid group provided some interesting ramifications.

The analysis placed the megalograptids with some other families belonging to the larger group Carcinosomatoidea. The interesting thing is that all other carcinosomatoids are typically at the top-end of the eurypterid family tree. Moving the megalograptids up from the bottom to join them at the top now means that we have one of the highest branches of the tree appearing first in geological time. The implication of this is that the whole tree has to be moved back in time. All the branches and splits that happen before we get to our carcinosomatoid group have to have occurred earlier than the time at which we find Pentecopterus. Whilst Pentecopterus is the earliest and most ‘primitive’ member of the megalograptids and carcinosomatoids, it cannot be the first eurypterid.

So, a quick recap: we found the oldest-yet eurypterid, we figured out it can’t actually be the first and we named it after a boat. And yet, we still haven’t got to the most-significant details of Pentecopterus. This lies within the exquisite preservation of the fossils.

If you are familiar with palaeontology, you may understand the fossil record is biased towards the preservation of the hard parts of organisms. The hard parts are useful and can tell us a lot about organisms: how they walked, how they ate, how they protected themselves, but most of the important information is lost. Consider your own body and the importance of your soft tissues and organs. Your sight, your touch, your taste, your reproductive organs. None of these would be preserved under normal circumstances. Soft-body preservation is exceedingly rare, but can provide unparalleled insights into extinct organisms. We have skin impressions from dinosaurs, muscle fibres from worms and optical pigments in squid. Pentecopterus has no soft-body preservation, but then again, it doesn’t need it.

Arthropods subscribe to a different ethos of construction; they wear their hard parts on the outside. This means that all their interactions with the environment occurs through their exoskeleton. Their eyes are hard and both their touch and taste is conducted through sensory hairs projecting through the hard cuticle. In Pentecopterus we find exceptional hard-body preservation. The fossils, though incomplete and disarticulated yield a treasure-trove of ecological information. The ‘teeth’ of Pentecopterus come equipped with thick spinose hairs, the legs and body bear the insertion sockets of finer hairs and swimming paddles have rows of sockets along the edges. What we’re seeing is how this organism sensed its environment. Although this information isn’t unique within eurypterids, it is exceedingly rare and this new species provides an essential point of comparison which hopefully will allow us to distinguish the exact function of the different hair types.

The Great Ordovician Biodiversification Event went on to shape the biosphere. It was a time of great change and whilst we may not know all of the events that occurred at the time, we may at least be able to discover how Pentecopterus felt about it.

By David Marshall, PhD student at the University of Bristol.

Reference

J. C. Lamsdell, Briggs D.E.G, Liu H.P., et al.: The oldest described eurypterid: a giant Middle Ordovician (Darriwilian) megalograptid from the Winneshiek Lagerstätte of Iowa, BMC Evolutionary Biology, doi 10.1186/s12862-015-0443-9, 2015

GeoEd: EGU General Assembly and GIFT 2015

GeoEd: EGU General Assembly and GIFT 2015

The most recent issue (Winter/Spring 2015) of the Teachers Clearinghouse for Science and Society Education Newsletter includes a piece, by Earth Science Correspondent, Michael J. Passow, on the 2015 General Assembly and the GIFT (Geosciences Information For Teachers) Workshop. Passow gives an account of this year’s workshop, on the topic of mineral resources, and outlines the participating teacher’s experience.

Each spring, the European Geosciences Union (EGU) General Assembly brings geoscientists from all over the world to Vienna for a conference covering all disciplines of the Earth, planetary and space sciences. EGU 2015, convening 12-17 April, provided a forum where scientists, especially early career researchers, could present their work and discuss their ideas with experts in all fields of geoscience. Concurrently, nearly 80 educators from around the world gathered for the 11th Geophysical Information for Teachers (GIFT) workshop of the EGU. They included, for the first time, your correspondent.

This year’s GIFT workshop welcomed 76 teachers from 21 different countries. GIFT 2015 centered on the theme “Mineral Resources.” Driving this selection was growing awareness that expansion of the world population from 6 to 9.6 billion in 2050 and rapid industrialization of highly populated countries, combined with an overall higher standard of living, are expected to intensify global competition for natural resources and place additional pressure on the environment, both terrestrial and marine. We recognize that mineral reserves are being depleted, and concerns are growing about access to new raw materials, especially basic and strategic minerals. Rise in the price of several essential metals, for example copper, has prompted some industrialized countries to initiate concerted activities to ensure access to strategic minerals.

Participants of the GIFT workshop at the 2015 General Assembly. Credit: Michael J. Passow, Earth Science Correspondent for the Teachers Clearinghouse for Science and Society Education Newsletter.

Participants of the GIFT workshop at the 2015 General Assembly. Credit: Michael J. Passow, Earth Science Correspondent for the Teachers Clearinghouse for Science and Society Education Newsletter.

Europe has recently begun initiatives that attempt to solve the issue. Europe depends greatly on imports for many materials needed for construction and heavy and high-tech industries. Recycling, resource efficiency, and searching for alternative materials are essential, but probably not sufficient to meet demands. There is a need to find new primary deposits. But politicians and business leaders are concerned because deposits, when identified, occur in areas difficult to access, barring modern exploration technology, and requiring huge investment costs. Exploration requires substantial capital, rare expertise, and leading edge technologies in order to secure the lowest extraction costs. GIFT 2015 matched teachers with experts of exploration, extraction, policy making in the field of future mineral resources, including the deep-sea frontier.

The EGU welcomed the teachers and started to bond them with a special guided visit to the Vienna Museum of Natural Sciences on Sunday, 12 April. They then joined all conference participants in the “Ice Breaker Party” at the Austria Center, where the scientific programs took place. Find out more information about EGU 2015 here.

Many of the participating teachers also contributed to the program through hands-on workshops, poster sessions, and other activities. Your correspondent presented in one of the hands-on workshop sessions classroom-based activities about minerals. Participants made models of the silicon-oxygen tetrahedron and other molecules using raisins and toothpicks. They shared strategies to teach important minerals properties, such as cleavage and magnetism, in their countries. An anticipated highlight was distributing samples of fluorescent minerals donated by the Sterling Hill Mining Museum in Ogdensburg, NJ, and watching them glow under ultraviolet energy.

Hands-on workshops at the GIFT workshop during the 2015 conference. Credit: Michael J. Passow, Earth Science Correspondent for the Teachers Clearinghouse for Science and Society Education Newsletter.

Hands-on workshops at the GIFT workshop during the 2015 conference. Credit: Michael J. Passow, Earth Science Correspondent for the Teachers Clearinghouse for Science and Society Education Newsletter.

Many of the teachers received partial conference expenses through professional societies and other sources. When participants return to their home countries, they are expected to complete an evaluation form to assess this year’s program and provide guidance for next year’s. Each will also make presentations about their EGU experience to teaching colleagues, submit reports and photographs about how GIFT information and resources have been used, and, contribute articles about the GIFT workshop to professional publications aimed at geosciences teachers.

You can learn about past GIFT workshops through the EGU website. Beginning in 2009, EGU has created web-TV presentations, which may be freely downloaded and used in classrooms. To expand the impact and outreach of the programs, the EGU Committee on Education began in 2012 a series of GIFT Distinguished Lectures in several European countries. Leading scientists who have participated as speakers in GIFT workshops during the EGU General Assemblies are supported to provide organized educational event for high school science teachers.

Similar GIFT Workshops are offered at the annual American Geoscience Union meetings held each fall in San Francisco. These are organized by the National Earth Science Teachers Association and the AGU Education Program. Resources from the previous four AGU GIFT workshops are available online.

by Michael J. Passow, Earth Science Correspondent

This article originally appeared in the Newsletter of the Teachers Clearinghouse for Science and Society Education.

For an electronic subscription to the Teachers Clearinghouse for Science and Society Education Newsletter please e-mail a request to JLRoeder@aol.com. You can also access the Newlsetter via the website of the American Association of Physics Teachers.

The GIFT Workshops are organised by the EGU’s Committee on Education. You can learn more about the GIFT programme and the other educational activities fostered by the Committee on the EGU website.

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/.

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