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geology

Discover geology with Lego!

Discover geology with Lego!

Science communication is becoming a widely recognized skill for both established and budding geoscientists alike. Outreach activities are beneficial in many ways, as they not only showcase science to the general public, but also give scientists the chance to develop transferable skills.

If you’re in the market for a creative geoscience activity, one that especially appeals to a younger audience, look no further! In this guest blog post, Stephanie Zihms, a geomechanics postdoc at Heriot-Watt University and the EGU Union-level ECS representative, details a fun hands-on activity that teaches geoscience with the help of Lego blocks. This post is modified from a version which first appeared on Stephanie Zihms’ blogRead the original post.

I designed this activity for the Explorathon 2015 (a family orientated science event) because I was looking for a way to show how geologists work from observing the surface to gathering information from boreholes and seismic surveys to understand the subsurface. I also wanted participants to experience this process without needing to be in the field or taking rock samples.

Kit and preparation

I used a generic brand of building bricks (because my budget didn’t allow for actual Lego) and bought two boxes of mixed bricks in a bargain store. First you want to sort the bricks by colour (unless you can buy them that way). Then you want to decide what shapes to make – I opted for three simples shapes: Syncline, Anticline and Oil Reservoir with seal.

With the geology built, you then want to select three or four areas to make a ‘borehole’ with – I used single bricks but this could be done with the 2×2 squares as well. If you have enough bricks you can probably incorporate the ‘boreholes’ into the model and reveal them by extracting them – which would be super cool. Once you have the models built and boreholes prepared, you need to make some envelopes to only expose the top layer – I used brown hacking paper and packing tape to make sure they can be reused easily. That’s pretty much it.

Activity: Syncline & Anticline       

Show your participants the covered models and ask if they can tell you what the rest of it looks like. You can explain that geologists use exposures like this for mapping (having maps on hand can be useful). Also ask how sure they are that they are correct based on the information available. You can then offer more information in form of boreholes – either lay or stand them in front of the model in the correct place (you can mark your envelopes) or extract them if you went for the hiding option.

Either ask the participants to show you what they can see – following a colour for example or ask them to copy the boreholes on a bit of paper and connect colours that way (this will depend on how much time you have with each participant; borehole papers can be prepared with the columns printed on so the participants only have to colour them in).

Once that is done reveal the full model. This is normally a big ‘Ahhh’ effect because just by having that little bit of extra information they got it right. This is a great opportunity to talk about information available and how geologists infer maps and what the subsurface looks like based on similar information. (if you have boreholes logs from the local area + the iGeology app from BGS this can really help relate this to the local area). If you make a version where the boreholes can be retrieved this could be standalone activity with instructions to follow as well.

Activity: Oil reservoir with seal         

This activity is very similar to the one above except that we can’t see anything from the top layer. And before we even know where to drill for a borehole we have to do a seismic survey. After guessing what the model looks like and deciding the information is not great. Show a generic seismic line (normally easily found online or in petroleum engineering tutorials). We printed seismic lines on A5 and asked participants to colour them in – following any features or structures they could see (this could also be done with one A3 paper that’s laminated and can be re-used).

After identifying a generic reservoir structure we revealed the model to show the different layers. A set of boreholes could be done based on where participants would ‘drill’. Which would mean having a set of boreholes available or making the middle of the model retrievable.

Summary

I absolutely love this activity because it uses something people are familiar with – independent of age and it mimics a little geological survey taking participants on the journey of gathering information and making an estimation. This activity can also be easily amended for different size audiences (e.g. using DUPLO for a show & tell type event) or adding more information about the process, talking about risk and uncertainty. The response from participants, especially children, when the model is revealed is priceless.

I hope you found this how-to useful and please share how you used it at your events either in the comments or by tagging me (@geomechsteph) on Twitter.

By Stephanie Zihms

Living in a new Age

Living in a new Age

If you were suddenly told you were living in a different time period, what would your immediate reaction be? Changes in the calendar – even if it’s just terminology – have proven emotive in the past. In 1752, when England shifted from the Julian to Gregorian calendars, and 11 days were cut from 1752 to catch up, there are suggestions that civil unrest ensued.

Once again, the name of the period in which we live has recently changed; the Holocene is now subdivided into three parts, and we’re now living in the Meghalayan age, according to the International Commission on Stratigraphy (ICS). While there weren’t riots in the streets this time, it has proved controversial for some researchers.

The division of time into different epochs and eras is an important part of stratigraphy. While time marches on, ignorant of the names humans give to its divisions, defining periods like the Cretaceous and Jurassic helps scientists compare results from around the world, even where the fossil and sedimentary records differ. It also draws into sharp focus the globally significant differences between each period, often including the devastating mass-extinctions that mark the boundaries of a handful of these periods.

The Holocene has been for at least a century the term favoured to describe the period in which we live, with its beginning marked by the end of the last ice age. The date at which the Holocene began has been more and more closely defined by experts over time, to the now accepted value of approximately 11,650 calendar years before present. The Holocene period encompasses the emergence of human civilisation, and represents a period of relatively warmer, somewhat stable climate in comparison with the prior ice age.

After considerable debate, however, the ICS has decided that the Holocene should be further subdivided; now, the period from 11,650 and 8,200 years before present is the Greenlandian; the Northgrippian stretches from 8,200 to 4,200 years before present, and the Meghalayan defines the time between then and the present. Why did the Holocene need to be divided up as such? If it wasn’t broken, why fix it?

The International Commission on Stratigraphy (ICS) has updated the timeline for the earth’s full geologic history, dividing the Holocene into three distinct periods. What does that mean for the Anthropocene? (Credit: International Commission on Stratigraphy)

The distinctions between an ice age and a warmer period, also known as an interglacial period, are globally significant, and a good place to start when describing how Earth’s climate has changed over the past few hundred thousand years. The swings in global temperature and ice extent are large enough that we often ignore the subtler climate changes that occur within an interglacial or glacial period. However, sediment and fossil records from more recent eras are relatively well preserved (simply because those records have had less chance to be destroyed by other geological processes), and this enables us to explore more recent periods in finer detail. Looking within the Holocene, the transition between the Greenlandian and Northgrippian is marked by a dramatic cooling of the climate, while the Northgrippian – Meghalayan by an abrupt ‘mega-drought’ and cooling that affected the nascent agricultural societies developing at that time.

By dividing the Holocene into these bite-sized chunks, the ICS has drawn attention to these changes in the earth’s geological system and provided a global context to the climatic shifts of the last ten thousand years. It also helps emphasise that climate can and does change on timescales more abrupt that glacial-interglacial periods – something we need to remember when considering the likely effects of anthropogenic climate change.

So far, so scientific. So why have the changes upset some people? Well, there’s an elephant in the stratigraphic room that looms larger now that these changes have been officially ratified. If there’s anything that has marked out the Holocene as fundamentally different from other historical ages, it’s the growth of human society. In particular, we are now at a point in history where the actions of a specific species – humans – can have global effects on the stratigraphic record.

Humans have added large quantities of carbon dioxide to the atmosphere, sown radioactive isotopes across the oceans from nuclear bomb testing, and left waste deposits in environments from the top of Mt Everest to the middle of the Pacific Ocean. Many of these impacts could leave lasting traces in the sedimentary and fossil records, leading to some scientists calling for a new period of time – the Anthropocene. And this may not fit well with the ICS changes.

I spoke with Helmut Weissert, President of the EGU Stratigraphy, Sedimentology and Palaeontology Division about these changes, and he suggested that the new changes devised by the ICS might shift the debate over the Anthropocene, at least in the short term:

I am quite worried. After the introduction of the new subdivisions I cannot see how the Holocene working group soon will vote for a further subdivision of the Holocene. The Anthropocene working group is confronted with a difficult task. I can envisage that the Anthropocene will be used as an informal term, not officially defined and introduced into the Stratigraphic Chart. I use the term regularly in my writing and in talks, everybody understands the term, I can explain how man is a geological agent. So, we may have to continue using an excellent term which is not yet properly defined, but most people do not care about the definition.

The Anthropocene is certainly an effective term to draw the attention of the wider public to the impact of society on global geological cycles. But from a stratigraphic perspective, it offers a number of challenges. Where and when, for example, should the beginning of the period be set? Changes in geological periods require specific chemical changes that can be identified globally and an internationally agreed upon reference point – a physical location – that defines the base of the section. There are many potential examples that could be chosen to define the beginning of human interference in the natural system; ice cores showing the uptick in carbon dioxide at the industrial revolution, or ocean sediments attesting to nuclear bomb tests in the 1950s. But the choice of which section to pick is fraught.

Each stratigraphic division needs a reference point that defines the split between the prior time period and the one in question. Here, a ‘golden spike’ defines the base of the Ediacaran period (635 million years ago) in the Flinders Ranges of South Australia. (Credit: Bahudhara via Wikimedia Commons)

Moreover, preservation is a crucial part of stratigraphy; how much of human impact will in fact be preserved, especially after further anthropogenic changes? What if we clean up the environment? What if we dredge the ocean floor for rare metals, and, in doing so, extirpate the signal of the 1950s nuclear bomb tests? What if we melt the ice caps that record the incipient CO2 increases from the industrial revolution? Sure, these changes may be recorded elsewhere, but how can we be sure a reference stratigraphic section will remain intact?

And this brings us to a perhaps more philosophical point: what if the human impact on the natural system we see today is only a fraction of what is to come? Any Anthropocene we define now would be based only upon the impact to date, but future changes may make these seem small in comparison. What would come after the Anthropocene? The question echoes that of 20th century philosophers, asking what comes after Post-Modernism? Perhaps instead of stratigraphy, we should look to written history and recorded data to better contextualise our impact.

Whether we end up defining our current era as the Meghalayan, the Anthropocene, or something else, it seems clear that the debate has drawn increased attention to the short-term climate changes – and in particular those driven by human intervention. A better public appreciation of our role within the natural system is a vital step in limiting damaging future climate change.

by Robert Emberson

Robert Emberson is a Postdoctoral Fellow at NASA Goddard Space Flight Center, and a science writer when possible. He can be contacted either on Twitter (@RobertEmberson) or via his website (www.robertemberson.com)

Imaggeo on Mondays: A Colombian myth with geologic origins

Imaggeo on Mondays: A Colombian myth with geologic origins

This photograph shows El salto del Tequendama, a natural waterfall of Colombia, located in the Department of Cundinamarca at an altitude of 2400 metres above sea level and approximately 30 kilometres southwest of the country’s capital, Bogotá.

The Salto del Tequendama is a space of transit and connectivity between the warm lands of the Magdalena river basin and the cold lands of the Sumapaz paramo, a Neotropical alpine tundra located at 4,000 metres above sea level.

Dutch-Colombian geologist Thomas Van der Hammen concluded that approximately 60,000 years ago the entire savannah of Bogota (populated today by 9 million people) was covered by a large lake, known as the Humboldt Lake, and the associated wetland plants instead of the paramo vegetation seen today.

Over time, the climate became warmer and the bottom of the Humboldt Lake began to rise. 30,000 years ago, the lake’s waters were channelled through the Bogota River and led to the Salto del Tequendama, a real climate event that we Colombians received through the myth of Bochica, a legendary hero to the Colombian indigenous group the Muisca. Here is the summarised myth of Bochica and the Tequendama jump:

“… As the Muiscas had lost respect for the gods, they offended Chibchacum, who had previously been the most beloved of their gods. He decided to punish them by flooding the savanna, for which he gave birth to the Sopo and Tivito rivers, which joined their rivers to the Funza (former name of the Bogotá River). The flood ended with many crops and human lives, until the people clamored with fasting and sacrifices to Bochica to free them from that calamity. The sage Bochica appeared on the rainbow and with his golden scepter, hit the rocks allowing the water to form a gigantic waterfall. So Bochica created the Tequendama jump.”

The large lake was partially dried and separated into smaller wetlands, where Andean plants, deer, foxes, weasels and more than 100 bird species made their home.

The waterfall, famous for its size, surrounding vegetation and vapourous waters, has been widely studied since 1668, when the Bishop of Panamá, Lucas Fernández de Piedrahíta made the first written record of its mythical origin story.

During the 18th and 19th centuries in particular, the Salto was one of the most famous natural attractions both locally and worldwide, due to the waterfall’s 157-metre drop onto a circular rocky abyss in a wooded region of permanent haze.

In the 19th century, large estates, also known as haciendas, were built on the region’s wetlands, and the natural environment was converted into places for fishing, hunting and logging. Through drainage channels, communities dried up the land to establish livestock and agricultural systems. In the last century, as the city of Bogota grew in population and size, the wetlands were filled to build neighborhoods, streets and avenues.

Like many Bogotanos, on a family weekend trip to relieve the stress generated by the chaos of the city and in search of clean air, I took this picture. The Salto was and always has been a fundamental part of the Bogota family mythology.

By Maria Cristina Arenas Bautista, National University of Colombia, Department of Civil Engineering and Agricultural (Bogotá)

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: Probing the Pliocene

Imaggeo on Mondays: Probing the Pliocene

The heights we go to for science…

This photograph shows a member of our team preparing to abseil down a cliff in the Charyn Canyon, in the Ili River basin of southeast Kazakhstan. The Charyn River and its tributaries, a branch of the Ili River north of the Tien Shan Mountains, have cut canyons up to 300 metres deep, carving through rocks of different geologic ages, some as old as 540 million years.

The name “Charyn” may derive from local Uighur or Turkic words for “ash tree” or “precipice” respectively, both of which are common in the area.

Charyn Canyon is presently characterized by a cold semi-arid climate, with dry summers and cold winters. However, these conditions are likely to have varied through time, becoming wetter, drier, warmer and cooler in response to major climate systems’ changing intensity and influence over the region.

Our research team investigates the past and present climate systems of the Cenozoic era, our current geological era which began 66 million years ago; the most recent 2.6 million years have been characterised by alternating ice ages and warmer so-called “interglacial” phases, and saw the evolution of humans. More specifically, we study climate systems in one of the most remote regions of Central Asia, known as the Eurasian Continental Pole of Inaccessibility. The area is a challenging place for climate research since it has no marine or ice core records, the most common calendars of ancient climate.

This region is poorly understood yet important within the global climate system, since it lies at the boundaries of the major northern hemispheric climate systems. These systems, such as the Siberian high pressure system and Asian monsoons, are likely to have shifted, expanded and contracted over time. These changes occur in response to factors like mountain uplift, and changes in the Earth’s orbital patterns and incoming solar radiation.

The aim of our study is to reconstruct climatic change over this period. By analysing various chemical and physical characteristics of the sediments, such as their age, magnetism, grain size and chemistry, we can reconstruct quantitative palaeoclimatic variability through time.

Here we focus on an 80-metre thick layer of sediment, which alternates between layers of river-transported gravels and wind-blown dust deposits, known as loess. Younger sedimentary layers have thicker dust deposits, reflecting a long-term aridification trend in the Ili Basin and, more broadly, Central Asia.

Our preliminary results from our fieldwork indicate that the canyon’s sediments represent an uninterrupted representation of the region’s climate from the Pliocene to early Pleistocene (from approximately 4.5 to 1 million years ago).

Achieving a comprehensive geological sampling of the Charyn Canyon was only possible by abseil. Our fieldwork, undertaken from May to June 2017, was a hot and dusty business, but ultimately a lot of fun. Definitely not for those with a fear of heights!

By Kathryn Fitzsimmons, Max Planck Institute for Chemistry, Germany and Giancarlo Scardia, São Paulo State University, Brazil