tag:theconversation.com,2011:/us/topics/clay-70988/articles
Clay – The Conversation
2024-03-25T12:39:22Z
tag:theconversation.com,2011:article/224152
2024-03-25T12:39:22Z
2024-03-25T12:39:22Z
What is dirt? There’s a whole wriggling world alive in the ground beneath our feet, as a soil scientist explains
<figure><img src="https://images.theconversation.com/files/582688/original/file-20240318-24-77z9su.jpg?ixlib=rb-1.1.0&rect=0%2C9%2C3110%2C2057&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Dig into soil and you'll find rock dust but also thousands of living species.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/little-childs-hands-digging-in-the-mud-royalty-free-image/619539728">ChristinLola/iStock/Getty Images Plus</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
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<p><strong>What is dirt? – Belle and Ryatt, ages 7 and 5, Keystone, South Dakota</strong></p>
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<p>When you think about dirt, you’re probably picturing soil. There’s so much more going on under our feet than the rock dust, or “dirt,” that gets on your pants.</p>
<p>When <a href="https://arts-sciences.und.edu/academics/biology/brian-darby/index.html">I began studying soil</a>, I was amazed at how much of it is actually alive. Soil is teeming with life, and not just the earthworms that you see on rainy days.</p>
<p>Keeping this vibrant world healthy is <a href="https://www.youtube.com/watch?v=Qas9tPQKd8w">crucial for food, forests and flowers to grow</a> and for the animals that live in the ground to thrive. Here’s a closer look at what’s down there and how it all works together.</p>
<figure class="align-center ">
<img alt="Cupped hands holds soil against a dark background with a tendril of plant root dangling through the fingers." src="https://images.theconversation.com/files/582689/original/file-20240318-20-8yglsj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/582689/original/file-20240318-20-8yglsj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/582689/original/file-20240318-20-8yglsj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/582689/original/file-20240318-20-8yglsj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/582689/original/file-20240318-20-8yglsj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/582689/original/file-20240318-20-8yglsj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/582689/original/file-20240318-20-8yglsj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Soil is a vibrant ecosystem.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/bokeh-photography-of-person-carrying-soil-jin4W1HqgL4">Gabriel Jimenez via Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<h2>The rocky part of soils</h2>
<p>If you scoop up a handful of dry soil, the basic dirt that you feel in your hand is actually very small pieces of <a href="https://passel2.unl.edu/view/lesson/c62dc027ae56/1">weathered rock</a>. These tiny bits eroded from larger rocks over millions of years.</p>
<p>The <a href="https://www.soils4teachers.org/physical-properties/">balance of these particles</a> is important for how well soil can hold water and nutrients that plants need to thrive. </p>
<p>For example, <a href="https://www.masterclass.com/articles/sandy-soil-guide">sandy soil</a> has larger rock grains, so it will be loose and can easily wash away. It won’t hold very much water. <a href="https://www.thespruce.com/understanding-and-improving-clay-soil-2539857">Soil with mostly clay</a> is finer and more compact, making it difficult for plants to access its moisture. In between the two in size is <a href="https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/what-is-silt.htm">silt, a mix of rock dust and minerals</a> often found in fertile flood plains.</p>
<p>Some of the most productive soils have a good balance of sand, clay and silt. <a href="https://www.masterclass.com/articles/how-to-create-loam-soil-for-your-garden">That combination</a>, along with the remnants of plants and animals that have died, helps the soil to retain water, allows plants to access that water and minimizes erosion from wind or rain.</p>
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<img alt="Three tipped over pots spill different types of soil – sandy is heavier grain, clay is finer grain and thicker, and loamy is darker." src="https://images.theconversation.com/files/581414/original/file-20240312-16-meqnvu.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/581414/original/file-20240312-16-meqnvu.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=371&fit=crop&dpr=1 600w, https://images.theconversation.com/files/581414/original/file-20240312-16-meqnvu.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=371&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/581414/original/file-20240312-16-meqnvu.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=371&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/581414/original/file-20240312-16-meqnvu.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=467&fit=crop&dpr=1 754w, https://images.theconversation.com/files/581414/original/file-20240312-16-meqnvu.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=467&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/581414/original/file-20240312-16-meqnvu.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=467&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Loamy soil, ideal for gardens, is a mix of sand, clay and silt.</span>
<span class="attribution"><a class="source" href="https://www.nesdis.noaa.gov/learn-about-soil-types">NOAA</a></span>
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<h2>The wriggling, munching parts of soil</h2>
<p>Among all those rock particles is a <a href="https://doi.org/10.3390/app10113717">whole world of living things</a>, each busy doing its job.</p>
<p>To get a sense of just how many creatures are there, picture this: The zoo in Omaha, Nebraska, boasts <a href="https://www.omahazoo.com/">over 1,000 animal species</a>. But if you scooped up a small spoonful of soil in your backyard, it would likely contain <a href="https://www.ceh.ac.uk/our-science/case-studies/case-study-why-do-soil-microbes-matter">at least 10,000 species</a> and around a billion living microscopic cells.</p>
<p>Most of those species are <a href="https://www.westernsydney.edu.au/newscentre/news_centre/story_archive/2018/first_soil_atlas">still largely a mystery</a>. Scientists don’t know much about them or what they do in soil. In fact, most species in soil don’t even have a formal scientific name. But each plays some kind of role in the vast soil ecosystem, including generating the <a href="https://www.aces.edu/blog/topics/farming/essential-plant-elements/">nutrients that plants need to grow</a>.</p>
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<a href="https://images.theconversation.com/files/581410/original/file-20240312-20-vn3j2x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two centipede-like creatures caught on camera immediately after a rock is lifted." src="https://images.theconversation.com/files/581410/original/file-20240312-20-vn3j2x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/581410/original/file-20240312-20-vn3j2x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=439&fit=crop&dpr=1 600w, https://images.theconversation.com/files/581410/original/file-20240312-20-vn3j2x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=439&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/581410/original/file-20240312-20-vn3j2x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=439&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/581410/original/file-20240312-20-vn3j2x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=552&fit=crop&dpr=1 754w, https://images.theconversation.com/files/581410/original/file-20240312-20-vn3j2x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=552&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/581410/original/file-20240312-20-vn3j2x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=552&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Lifting a rock reveals a symphylan, or garden centipede, left, and a poduromorph, or plump springtail, munching through the soil.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Symphylan_%26_poduromorph_springtail_(3406419924).jpg">Marshal Hedin via Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>Imagine a leaf falling from a tree in late autumn.</p>
<p>Inside that leaf are a lot of nutrients that plants need, such as nitrogen, potassium and phosphorus. There is also a lot of <a href="https://scied.ucar.edu/learning-zone/earth-system/biogeochemical-cycles">carbon in that leaf</a>, which holds energy that can be used by other organisms such as bacteria and fungi.</p>
<p>The leaf itself is too large for a plant to take up through its roots, of course. But that leaf can be broken down into smaller and smaller pieces. This process of breaking down plant and animal tissue is <a href="https://youtu.be/IBvKKMzXYtY?feature=shared">known as decomposition</a>.</p>
<p>When the leaf first falls to the ground, <a href="https://doi.org/10.3390%2Finsects11010054">arthropods</a> – such as insects, mites and <a href="https://www.chaosofdelight.org/collembola-springtails">collembolans</a> – break the leaf down into smaller chunks by shredding the tissue. Then, an <a href="https://youtu.be/n3wsUYg3XV0?feature=shared">earthworm might come along</a> and eat one of the smaller chunks and break it down even more in <a href="https://www.pbs.org/video/how-do-worms-turn-garbage-into-compost-jwj6cm/">its digestive tract</a>.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/2Pa1FwmKZcQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">PBS explores how earthworms help turn dead plants into fertile soil.</span></figcaption>
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<p>Now the broken-up leaf is small enough for microbes to come in. <a href="https://ohioline.osu.edu/factsheet/anr-36">Bacteria</a> and <a href="https://ohioline.osu.edu/factsheet/anr-37">fungi secrete enzymes</a> into the soil that further break down organic material into even smaller pieces. If enough microbes are active, eventually this organic material will be broken down enough that it can dissolve in water and be taken up by plants that need it.</p>
<p>To aid in this process, there are many small animals, such as <a href="https://www.canr.msu.edu/news/are_soil_nematodes_beneficial_or_harmful">nematodes</a> and <a href="https://www.livingsoil.net/protozoa">amoebae</a>, that consume bacteria and fungi. There are also predatory nematodes that feed on other nematodes to make sure they don’t become too abundant, so everything remains in balance as much as possible. </p>
<p>It’s quite a complicated food web of interacting species in a delicate balance.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/IBvKKMzXYtY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A time-lapse video filmed about 4 inches underground shows a leaf decomposing over 21 days in July. At the end, radish roots make their way down into the soil. Video by Josh Williams.</span></figcaption>
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<p>While some fungi and bacteria <a href="https://www.growingagreenerworld.com/bacteria-fungus-and-viruses-an-overview/">can harm plants</a>, there are many species that are considered beneficial. In fact, they <a href="https://www.nrcs.usda.gov/conservation-basics/natural-resource-concerns/soils/soil-health">may be the key</a> to figuring out how to grow enough crops to feed everyone without degrading and overburdening the soil.</p>
<h2>Figuring out your soil type</h2>
<p>Scientists have named <a href="https://www.nrcs.usda.gov/resources/education-and-teaching-materials/soil-facts">over 20,000 different types</a> of unique soils. If you’re curious about the <a href="https://www.nesdis.noaa.gov/learn-about-soil-types">soil and dirt in your area</a>, the University of California, Davis has a <a href="https://casoilresource.lawr.ucdavis.edu/gmap/">website where you can learn</a> more about local soils and their chemical and physical attributes.</p>
<p><a href="https://www.farmers.gov/conservation/soil-health">Caring for soil</a> to promote its living creatures’ benefits and minimize their harm takes work, but it’s essential for keeping the land healthy and growing food for the future.</p>
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<p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
<p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/224152/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brian Darby receives funding from the United States Department of Agriculture. </span></em></p>
Rock dust is only part of the story of soil. Living creatures, many of them too tiny to see, keep that soil healthy for growing everything from food to forests.
Brian Darby, Associate Professor of Biology, University of North Dakota
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/184470
2022-06-26T19:58:47Z
2022-06-26T19:58:47Z
How Japanese avant-garde ceramicists have tested the limits of clay
<figure><img src="https://images.theconversation.com/files/469709/original/file-20220620-12-gvokm8.jpg?ixlib=rb-1.1.0&rect=0%2C4%2C1497%2C1994&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Nakashima Harumi, born Ena City, Gifu prefecture, 1950, Struggling forms, c2005, Ena City, Gifu prefecture, porcelain, under and overglaze, 66.0 x 49.0 x 43.0 cm. </span> <span class="attribution"><span class="source">Collection of Raphy Star</span></span></figcaption></figure><p><em>Review: Pure Form, Art Gallery of South Australia.</em></p>
<p>Japanese art post the second world war is infinitely fascinating. At a time when the country was under Allied occupation and Japan had paid a high price for the war in the Pacific to end, its artists were revelling in new found freedom. </p>
<p>Some of the most interesting work of this era was from avant-garde ceramicists. Their revolution in clay led to them abandoning the <a href="https://japanobjects.com/features/mingei">Mingei tradition</a> of Japanese folk craft which included making functional vessels such as tea bowls. </p>
<p>In its place, they redefined themselves as artists, placed a premium on individual expression and, as <a href="https://www.tate.org.uk/art/art-terms/m/modernism">modernists</a> with a Japanese inflection, began producing abstract sculptural ceramics. </p>
<p>Three generations of artists now work in this style, and their stunning work stretching from the late 1940s to 2021 is the subject of the Art Gallery of South Australia’s exhibition Pure Form. The title underscores the shift in ceramics from function to form.</p>
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Read more:
<a href="https://theconversation.com/kintsugi-and-the-art-of-ceramic-maintenance-64223">Kintsugi and the art of ceramic maintenance</a>
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<h2>A delicate and refined aesthetic</h2>
<p>In a time of often unnamed craftsmen producing humble ceramic objects for everyday use integral to the Mingei tradition, five Kyoto-based ceramicists were abreast of international trends in avant-garde modernism. They formed a group called Sōdeisha, meaning “crawling through the mud association” in 1948. </p>
<p>There was initially a gradual shift to pure form, as seen in Yamada Hikaru’s Glazed jar with sgraffito (scratched decoration) (1951-52). Its shape still alludes to a functional vessel while its <a href="https://www.lakesidepottery.com/Pages/Pottery-tips/How-to-create-sgraffito-pottery-tutorial.htm">sgraffito linework</a> – a decorative technique of incising into pale slip to reveal the clay beneath – is steeped in Korean ceramics. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/469678/original/file-20220620-20-q9qj8w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/469678/original/file-20220620-20-q9qj8w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/469678/original/file-20220620-20-q9qj8w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=723&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469678/original/file-20220620-20-q9qj8w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=723&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469678/original/file-20220620-20-q9qj8w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=723&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469678/original/file-20220620-20-q9qj8w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=909&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469678/original/file-20220620-20-q9qj8w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=909&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469678/original/file-20220620-20-q9qj8w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=909&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Suzuki Osamu, born Kyoto 1926, died Kyoto 2001, Square vase on pedestal foot (Koku yū hōko), c.1950-60, Kyoto, stoneware with overglaze, 23.3 x 13.0 cm.</span>
<span class="attribution"><span class="source">Gift of Norman Sparnon 1988, Art Gallery of New South Wales, © Suzuki Osamu, photo: Felicity Jenkins</span></span>
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<p>Other works in the exhibition reference surrealism, such as Square vase on pedestal foot (1950-60) by Sōdeisha member Suzuki Osamu. There are vases devoid of openings, elongated forms negating function, or, as with second-generation Sōdeisha artist Hayashi Hideyuki’s Walk (c. 1980), a minimal geometric form referencing the human body.</p>
<p>A delicate and refined aesthetic underpins the work on show, such as that of Matsutani Fumio, a third-generation artist whose ceramics balance innovation with tradition, as in his Yellow (Ou) (2021). This is a flamboyant extension of the architecture of the tea bowl, replete with beautiful line work. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/469675/original/file-20220620-26-uclstg.jpg?ixlib=rb-1.1.0&rect=0%2C415%2C1497%2C1432&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/469675/original/file-20220620-26-uclstg.jpg?ixlib=rb-1.1.0&rect=0%2C415%2C1497%2C1432&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/469675/original/file-20220620-26-uclstg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469675/original/file-20220620-26-uclstg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469675/original/file-20220620-26-uclstg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469675/original/file-20220620-26-uclstg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469675/original/file-20220620-26-uclstg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469675/original/file-20220620-26-uclstg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Matsutani Fumio, born Ehime prefecture 1975, Yellow (Ou), 2021, Ehime prefecture, stoneware, 43.2 x 52.3 x 28.2 cm.</span>
<span class="attribution"><span class="source">Collection of Raphy Star, © Matsutani Fumio, photo: Grant Hancock</span></span>
</figcaption>
</figure>
<p>In terms of drama, Moriyama Kanjiro’s metallic glazed Kai (Turn) (2020) takes the honours for simulating movement. Its tower-like form is constructed from individual pieces assembled and fired to make a stunning swirling sculpture.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/469701/original/file-20220620-24-nba5kz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/469701/original/file-20220620-24-nba5kz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/469701/original/file-20220620-24-nba5kz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=897&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469701/original/file-20220620-24-nba5kz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=897&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469701/original/file-20220620-24-nba5kz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=897&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469701/original/file-20220620-24-nba5kz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1127&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469701/original/file-20220620-24-nba5kz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1127&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469701/original/file-20220620-24-nba5kz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1127&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Installation view: Pure Form: Japanese sculptural ceramics, featuring Kai (Turn) VIII.
by Moriyama Kanjiro.</span>
<span class="attribution"><span class="source">Art Gallery of South Australia, Adelaide; photo: Saul Steed</span></span>
</figcaption>
</figure>
<h2>Women’s ceramic art and the broader diaspora</h2>
<p>One of the many strengths of this exhibition is its focus on women of the calibre of Tsuboi Asuka, who was instrumental in establishing the Women’s Association of Ceramic Art in Kyoto in 1957. </p>
<p>Women’s rights came to the fore during the occupation, along with suffrage, and women ceramicists gained visibility. </p>
<p>Tsuboi’s three panel work Untitled (c. 2005) delicately inserts Japanese textile patterns in clay, each panel taking on the movement of cloth swaying in the wind. </p>
<p>Another is Tanaka Yu, whose clever wrapped bundles in clay imitate reality. Her Yellow sculpture in the shape of a furoshiki (c. 2108), looking like a beautifully wrapped object complete with a knotted tie, is informed by the ancient Japanese art of cloth wrapping.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/469679/original/file-20220620-23-bzjl62.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/469679/original/file-20220620-23-bzjl62.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/469679/original/file-20220620-23-bzjl62.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469679/original/file-20220620-23-bzjl62.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469679/original/file-20220620-23-bzjl62.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469679/original/file-20220620-23-bzjl62.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469679/original/file-20220620-23-bzjl62.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469679/original/file-20220620-23-bzjl62.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Tanaka Yū, born Ehime prefecture 1989, Yellow sculpture in the shape of a furoshiki, c.2018, Kyoto, stoneware, matte glaze, 46.0 x 54.0 x 38.5 cm.</span>
<span class="attribution"><span class="source">Collection of Raphy Star, © Tanaka Yū, photo: Hazuki Kani</span></span>
</figcaption>
</figure>
<p>Japanese-trained ceramic sculptors now form a diaspora working outside Japan – one is US-based Kaneko Jun in Nebraska, whose large hand-built forms such as Untitled triangle (dango) (2004), employ abstract design features. </p>
<p>Uranishi Kenji is another emigre, based in Brisbane since 2004. His white glazed objects portray the wondrous world of coral in the Great Barrier Reef.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/in-japan-supernatural-beliefs-connect-the-spiritual-realm-with-the-earthly-objects-around-us-125726">In Japan, supernatural beliefs connect the spiritual realm with the earthly objects around us</a>
</strong>
</em>
</p>
<hr>
<h2>Balancing tradition and the new</h2>
<p>The porcelain sculpture on show is superb. Matsuda Yuriko’s erotically charged foot, In her shoes (c. 2007), with its tightly curled back toes suggesting sexual pleasure, is a stunning piece. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/469702/original/file-20220620-22-vqjuq3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/469702/original/file-20220620-22-vqjuq3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/469702/original/file-20220620-22-vqjuq3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469702/original/file-20220620-22-vqjuq3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469702/original/file-20220620-22-vqjuq3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469702/original/file-20220620-22-vqjuq3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469702/original/file-20220620-22-vqjuq3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469702/original/file-20220620-22-vqjuq3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Matsuda Yuriko, born Ashiya, Hyōgō, 1943. In her shoes, c2007, Oshino, Yamanashi prefecture, porcelain, underglaze blue and overglaze enamels, 33.0 x 31.0 x 16.0 cm (foot),2.0 x 41.0 x 33.0 cm (base).</span>
<span class="attribution"><span class="source">Collection of Raphy Star</span></span>
</figcaption>
</figure>
<p>Her subject is frequently the female body. Here, the decorative surface evokes the patterning of <a href="https://www.mayfairgallery.com/blog/japanese-meiji-period-art-antiques/">Meiji ceramics</a> while its subject matter sits squarely in the Japanese tradition of <em><a href="https://en.wikipedia.org/wiki/Shunga">shunga</a></em>, or erotic imagery. Refreshingly, it comes from the perspective of a woman. </p>
<p>Yet another porcelain piece, Struggling forms (c. 2005) by Nakashima Harumi, looks almost octopus-like, but has only two feet. Its twists echo that of a Möbius strip, it looks disarmingly like an impossible form, but achieves perfect balance. The blue colour of the dot patterning harks back to the Japanese tradition of <em><a href="https://kogeijapan.com/locale/en_US/setosometsukeyaki/">sometsuke</a></em> which is underglaze painting in cobalt blue on porcelain or stoneware.</p>
<p>In contrast to referencing tradition, Mishima Kimiyo’s ceramic forms in Box Batter -17 (2017) shows bottles in newspaper wrappings in a roughly opened box, very much of their time. Her interest is the imbalance between the human footprint and nature, seen in the detritus of modern life, newspapers, packaging and soft drink bottles littering the environment.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/469704/original/file-20220620-15-f3ixby.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/469704/original/file-20220620-15-f3ixby.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/469704/original/file-20220620-15-f3ixby.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469704/original/file-20220620-15-f3ixby.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469704/original/file-20220620-15-f3ixby.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469704/original/file-20220620-15-f3ixby.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469704/original/file-20220620-15-f3ixby.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469704/original/file-20220620-15-f3ixby.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mishima Kimiyo, born Osaka, Japan,1932, Box Batter -17,2017, Osaka, stoneware, silk screen prints, 22.0 x 31.0 x 25.0 cm (box), 22.5 x 6.5 cm (bottle, each).</span>
<span class="attribution"><span class="source">Collection of Raphy Star</span></span>
</figcaption>
</figure>
<h2>The limits of clay</h2>
<p>This is a must-see exhibition. </p>
<p>Its 100 plus artworks by 65 ceramicists drawn from public and private collections in Australia and Japan, and spanning modern and contemporary work, are dazzling in innovation, skill and aesthetic. </p>
<p>The sculptural leap to pure form in porcelain in Fukami Sueharu’s To the sky (c. 2013), simulates flight itself and leaves viewers elevated by the experience. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/469708/original/file-20220620-15-ch956e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/469708/original/file-20220620-15-ch956e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/469708/original/file-20220620-15-ch956e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=429&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469708/original/file-20220620-15-ch956e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=429&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469708/original/file-20220620-15-ch956e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=429&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469708/original/file-20220620-15-ch956e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=539&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469708/original/file-20220620-15-ch956e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=539&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469708/original/file-20220620-15-ch956e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=539&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fukami Sueharu, born Kyoto, Kyoto prefecture 1947, To the sky, c.2013, Kyoto , slip cast porcelain, celadon glaze (seihakuji), base: walnut , 31.0 x 88.0 x 24.0 cm.</span>
<span class="attribution"><span class="source">Collection of Raphy Star , © Fukami Sueharu , photo: Grant Hancock</span></span>
</figcaption>
</figure>
<p>While in the exhibition space, I could hear some, including senior artists, puzzling as to how several of the ceramic objects were actually produced. These ceramicists have indeed tested the limits of clay.</p>
<p><em>Pure Form is at the Art Gallery of South Australia until November 6.</em></p><img src="https://counter.theconversation.com/content/184470/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Catherine Speck has received funding in past years from the Australian Research Council to research art exhibitions. </span></em></p>
Pure Form at the Art Gallery of South Australia brings together some of Japan’s most interesting post-war art.
Catherine Speck, Emerita Professor, Art History and Curatorship, University of Adelaide
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/181627
2022-04-21T13:54:34Z
2022-04-21T13:54:34Z
How geology put a South African city at risk of landslides
<figure><img src="https://images.theconversation.com/files/459089/original/file-20220421-18-ts22r7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">This aerial view shows the destruction at Umdloti beach north of Durban. Landslides and floods wreaked havoc.</span> <span class="attribution"><span class="source">Marco Longari/AFP via Getty Images</span></span></figcaption></figure><p>There had been suggestions that the catastrophic landslides in Durban and the greater eThekwini region of South Africa following floods in 2022 were due to <a href="https://www.dailymaverick.co.za/article/2022-04-14-explainer-why-kzn-was-flooded-and-why-its-likely-to-happen-again/?utm_source=top_reads_block&utm_campaign=south_africa">climate change</a> and <a href="https://www.dailymaverick.co.za/article/2022-04-18-kzn-flood-tragedy-exposes-dysfunctional-province-in-midst-of-governance-crisis/">maladministration</a>. While these factors played a role, the fact that landslides occurred comes as no surprise, considering the geology of the area.</p>
<p>eThekwini is a coastal metropolis characterised by hilly terrain dissected by several major rivers such as the Umgeni, Mlazi and Mbokodweni. The region is subtropical, but rains in recent years have been unprecedented and resulted in multiple landslides. </p>
<p>Some of the earliest studies of landslides in the region date to the <a href="https://doi.org/10.1016/0013-7952(75)90034-4">1930s</a>. Mitigation measures including zoning <a href="http://www.durban.gov.za/Documents/City_Government/development_planning_management/Bluff%20Slopes%20-%20Special%20Bylaws.pdf">regulations</a> are in place for some parts of the region. But knowledge of the geotechnical risks of the area didn’t prevent tragic disaster. </p>
<p>As a geotechnical engineer I study the effects of water on the stability of sloping ground. Many natural slopes are in a delicate state of equilibrium: the downward movement of the inclined soil is just balanced by the resisting strength between the soil grains.</p>
<p>When water is introduced, the water pressure pushes soil particles apart, reducing this strength. Also some soils, such as clays, are more slippery and present an even greater landslide risk. </p>
<p>In eThekwini, sloping ground, water and clay combined to leave devastation in their wake.</p>
<h2>Greater eThekwini geology</h2>
<p>Ground adjacent to the sea from Durban to Mtunzini (a coastal town 140km north of Durban) is almost exclusively made up of ancient red sand dunes termed the Berea formation. South of the Durban harbour these sands form a ridge called the Bluff and north of the harbour they form the Berea Ridge. In some places these sand dunes are extremely steep.</p>
<p>The sands of the Berea formation were subject to intense investigation in the late 1950s following landslides <a href="https://www.osti.gov/etdeweb/biblio/5230023">along the Bluff</a>. The strength of the Berea sands was not uncharacteristic for sandy material. But the Bluff slopes were steeper than would be expected based on the soil’s strength. The only reason the slopes hadn’t collapsed was that plant growth was reinforcing the soil.</p>
<p>The investigation showed the slopes’ stability was not significantly affected by rainfall. That makes sense as these slopes have been battered by storms over geological time. But concentrated flows from poorly controlled flood water or broken water pipes were found to be catastrophic.</p>
<p>The reason is that as the Berea sands have little to no clayey stickiness, or plasticity, they are extremely prone to erosion. When large torrents of water flow over the sands they simply erode to form <a href="https://www.timeslive.co.za/news/south-africa/2022-04-13-watch-aerial-footage-shows-severe-devastation-from-kzn-floods/">gulleys</a>. The video below clearly demonstrates the power of water over these loose sands.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/S_j9W31ScRQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Umdloti has been devastated by heavy rainfall, mudslides and landslides.</span></figcaption>
</figure>
<h2>Inland shales</h2>
<p>Inland from Durban are shales of the Pietermaritzburg formation. They dip down from their main exposure in the inland city of Pietermaritzburg towards the sea at Durban.</p>
<p>These shales were formed from thin layers of clay and silt deposited in slow-moving water bodies during the geological past. When exposed at the surface, the shales break down or weather. Depending on their mineral content, some layers weather to very slippery clay.</p>
<p>It only takes a small increase in water pressures along these layers to trigger a landslide. The shales are not very permeable, so it can take a long time for the water pressure to become high enough to cause instability. It could eventually happen as a result of seepage from leaking pipes or long rainy seasons.</p>
<p>The residential area of Clare Estate, which witnessed landslides during the <a href="https://www.nytimes.com/2022/04/12/world/africa/floods-mudslides-south-africa.html">flooding</a> in 2022, is built on these shales. Tragically this is not the first time landslides have occurred <a href="http://doi.org/10.13140/2.1.1871.3601">here</a>. Slides in these shales have been investigated since the <a href="https://doi.org/10.1016/0013-7952(75)90034-4">1930s</a>. </p>
<h2>Natal group sandstones</h2>
<p>Another part of the geology of eThekwini are the sandstones of the Natal group. These sandstones weather into a sandy material but there are also layers containing clay. While water can easily flow into the sandy layers it can become trapped by the clayey layers.</p>
<p>During heavy rainfall events this can cause excess water pressure, liquefying the sand so it runs like water. A review of landslides in the eThekwini region between 1971 and 1991 showed that when short rainfall events exceeded 20% of mean annual rainfall, landslides <a href="http://doi.org/10.1007/s002549900077">could be expected</a>.</p>
<p>During the 2022 floods, over 300mm fell over four days (9-11 April 2022), equating to <a href="https://www.weathersa.co.za/Documents/Corporate/Medrel12April2022_12042022142120.pdf">30% of mean annual rainfall</a>. This clearly exceeded the landslide threshold. The situation was made worse by the storms coming at the end of the rainy season when the ground was already saturated.</p>
<p>Sadly, the houses of the KwaNdengezi settlement near Durban were no match for the forces of nature unleashed by the deluge of water over those <a href="https://www.reuters.com/news/picture/heavy-rains-claim-45-lives-in-south-afri-idUSKCN2M41BT">three days</a>. Some houses were swept away as the ground gave way and others were simply too close to flood lines to withstand the surging water.</p>
<h2>Mitigation measures</h2>
<p>Landslides in the eThekwini region should come as no surprise. We know which areas are at risk and why. Zoning and early warning systems would seem to be logical measures to take. </p>
<p>The eThekwini municipality does have <a href="http://www.durban.gov.za/Documents/City_Government/development_planning_management/Bluff%20Slopes%20-%20Special%20Bylaws.pdf">by-laws in place for some risky areas like the Bluff</a> and it does publish maps <a href="http://gis.durban.gov.za/cmv-cgis/viewer/?config=cgisPublicViewer">highlighting areas of risk</a>. The 2022 landslides suggest more work is required to fully zone the region and to enforce by-laws.</p>
<p>Landslide mitigation is always difficult, though. Landslide zoning has met with fierce political resistance in Japan and the US as land devalues if marked as <a href="https://hdl.handle.net/10520/EJC189270">risky</a>. Landslide prediction systems are also costly to implement and can warn residents too late.</p>
<p>Anywhere in the world, the technical problems surrounding landslide mitigation are often the least challenging to solve. The real problems typically lie with social and political issues which require considerable finesse and thought to resolve.</p><img src="https://counter.theconversation.com/content/181627/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Charles MacRobert does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Sloping ground, water and clay combined to leave devastation in its wake in Durban.
Charles MacRobert, Senior lecturer, Stellenbosch University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/157840
2021-05-02T12:41:31Z
2021-05-02T12:41:31Z
From making wine to managing mine waste, clay is important for many industries
<figure><img src="https://images.theconversation.com/files/397445/original/file-20210427-21-1jamobb.jpg?ixlib=rb-1.1.0&rect=0%2C9%2C3008%2C1985&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The unique properties of clays make them suitable for a wide variety of applications.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>The discovery and use of clays dates back to <a href="https://ceramics.org/about/what-are-engineered-ceramics-and-glass/brief-history-of-ceramics-and-glass">30,000 years ago</a>, making clays one of the oldest materials used in society. Clays are naturally occurring materials that were first used to make pottery and are now used abundantly in the manufacturing of goods, including ceramics, cosmetics and building materials. Clays also play <a href="http://doi.org/10.1007/s00706-019-02454-y">an important role in the “terroir,” the features a wine develops based on where the grapes are grown</a>.</p>
<p>Clay has unique properties that are useful in industries ranging from manufacturing to construction. But these properties can also pose a challenge in managing mine waste.</p>
<p>Clays and clay minerals are tiny particles with a unique <a href="https://www.srs.fs.usda.gov/pubs/ja/ja_barton002.pdf">plate-like structure less than two microns</a> in size (for comparison, the average thickness of a strand of human hair is about 70 microns). The small size of clay minerals and their distinct structure give them unique properties, and different types of clay minerals can exhibit diverse characteristics. </p>
<h2>Properties of clays</h2>
<p>There are <a href="https://doi.org/10.1080/24749508.2017.1361128">four main groups of clay mineral</a>: kaolinite, illite, vermiculite and smectite. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/397447/original/file-20210427-19-1sscsbp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An illustration of the molecular structure of kaolinite clay" src="https://images.theconversation.com/files/397447/original/file-20210427-19-1sscsbp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/397447/original/file-20210427-19-1sscsbp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=471&fit=crop&dpr=1 600w, https://images.theconversation.com/files/397447/original/file-20210427-19-1sscsbp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=471&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/397447/original/file-20210427-19-1sscsbp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=471&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/397447/original/file-20210427-19-1sscsbp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=591&fit=crop&dpr=1 754w, https://images.theconversation.com/files/397447/original/file-20210427-19-1sscsbp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=591&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/397447/original/file-20210427-19-1sscsbp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=591&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Clay minerals are classified based on the arrangement of their molecules and layers.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>Smectite clays for example, have the greatest ability to swell, often expanding several times their initial volume. Bentonite clay, a smectite, can <a href="https://doi.org/10.1016/j.enggeo.2011.10.003">swell up to 18 times its initial volume</a> by taking water into its interlayer, the distance between two layers of clays. This property makes it useful as a spill absorbent, but also means that it is very difficult to remove water from clay in dewatering processes, as in the case of mine waste management.</p>
<p>In contrast, kaolin, or china clay, does not swell and has low permeability, making it preferable for <a href="https://doi.org/10.1179/1745823414Y.0000000008">producing porcelain</a> or <a href="https://doi.org/10.1016/0169-1317(91)90015-2">improving the printability of paper</a>. </p>
<p>Clays also develop plasticity when wet, giving them the ability to stretch without breaking or tearing — a critical property for pottery sculpting. The <a href="http://doi.org/10.13140/RG.2.2.10554.70086">drying and firing processes</a> cause the water molecules to escape from between the clay sheets, and irreversibly changing the chemical structure of the clays, turning the piece into a hard and long-lasting pottery piece.</p>
<h2>Clay and wine</h2>
<p>Vineyard owners use their knowledge of clay content in the soil to help them make decisions about planting and irrigation so that they can improve the quality of the wine they produce. The soil composition in vineyards influences the drainage levels and the uptake of minerals and nutrients for the roots. Sandy soils are great for drainage, and clays, which have a net negative charge, help <a href="http://www.soilquality.org.au/factsheets/cation-exchange-capacity">retain positively charged nutrients including calcium, magnesium and potassium</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/397755/original/file-20210429-17-1esa900.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Vineyards with red clay soil" src="https://images.theconversation.com/files/397755/original/file-20210429-17-1esa900.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/397755/original/file-20210429-17-1esa900.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/397755/original/file-20210429-17-1esa900.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/397755/original/file-20210429-17-1esa900.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/397755/original/file-20210429-17-1esa900.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/397755/original/file-20210429-17-1esa900.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/397755/original/file-20210429-17-1esa900.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The composition of the soil and clays that grapes are grown in can affect the taste of the wine. Vineyard owners can use this knowledge to produce specific notes.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>Clays also hold water quite well, which can be helpful in dry climates to keep the soil cooler and wetter. Certain vine varieties produce the best results in a particular soil type. For example, clay soils tend to produce <a href="https://sommelierschoiceawards.com/en/blog/insights-1/soil-types-that-matter-for-grape-growing-164.htm">bold and muscular red wines like sangiovese and merlot</a> and <a href="https://www.winc.com/blog/how-soil-type-affects-your-wine">white wines like chardonnay</a>.</p>
<h2>Clay in mine waste</h2>
<p>While clays can be valuable materials in certain industrial processes, they can also cause problems in mine waste management. For example, <a href="https://www.capp.ca/explore/tailings-ponds/">oilsands tailings</a> — produced from the surface mining of oilsands — consist of a mixture of water, sand, fine particles, clays and residual bitumen. </p>
<p>These tailings are stored in ponds, where the heavier sands settle quickly to the bottom and the fine particles and clays remain suspended. The water-loving nature of clays means that a lot of water is trapped in the tailings, making consolidation and subsequent reclamation very challenging. </p>
<p>As of 2018, there are <a href="https://static.aer.ca/prd/documents/oilsands/2018-State-Fluid-Tailings-Management-Mineable-OilSands.pdf">more than 1.2 trillion litres of fluid tailings</a> accumulated in these ponds in Alberta. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/398129/original/file-20210430-21-e9zkiv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Alternating stripes of bitumen, water, sand and grass at a mine's tailings pond" src="https://images.theconversation.com/files/398129/original/file-20210430-21-e9zkiv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/398129/original/file-20210430-21-e9zkiv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/398129/original/file-20210430-21-e9zkiv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/398129/original/file-20210430-21-e9zkiv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/398129/original/file-20210430-21-e9zkiv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/398129/original/file-20210430-21-e9zkiv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/398129/original/file-20210430-21-e9zkiv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Bitumen, water, sand and grass at a mine’s tailings pond, where the fine particles and clays gradually settle. Oilsands tailings are waste materials produced from extracting bitumen from the Alberta oilsands.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>This fluid tailings problem is not exclusive to oilsands as all forms of mining — such as copper, potash and diamond — produce tailings. As the <a href="https://www.worldbank.org/en/news/press-release/2020/05/11/mineral-production-to-soar-as-demand-for-clean-energy-increases">global production of minerals and metals continue to rise</a>, so does the production of tailings. </p>
<p>Clay measurement methods will become increasingly important to monitor and optimize tailings management strategies.</p>
<h2>Treatment methods</h2>
<p>Many tailings treatment solutions modify clay properties to accelerate dewatering and consolidation, and so understanding the clays present is critical for any treatment methods to work. </p>
<p>Clays can be characterized based on <a href="https://doi.org/10.1080/24749508.2017.1361128">particle size, mineral type, surface area, cation exchange capacity, plasticity and flow behaviour</a>. In a laboratory setting <a href="https://www.researchgate.net/publication/282662304_DEMYSTIFYING_THE_METHYLENE_BLUE_INDEX">used in the oilsands industry for decades</a>, methylene blue dye can help determine some of these important properties.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/397161/original/file-20210426-21-1xn4rfz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/397161/original/file-20210426-21-1xn4rfz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/397161/original/file-20210426-21-1xn4rfz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/397161/original/file-20210426-21-1xn4rfz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/397161/original/file-20210426-21-1xn4rfz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/397161/original/file-20210426-21-1xn4rfz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/397161/original/file-20210426-21-1xn4rfz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/397161/original/file-20210426-21-1xn4rfz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">NAIT researchers are integrating robotics, sensors and optical systems to automate the methylene blue index laboratory method.</span>
<span class="attribution"><span class="source">(Author provided)</span></span>
</figcaption>
</figure>
<p>The Northern Alberta Institute of Technology and its partners are developing an <a href="https://www.nrcan.gc.ca/science-data/funding-partnerships/funding-opportunities/current-investments/development-line-active-clay-analyzer-canadian-mining-industry/22904">automated clay analyzer</a> based on the <a href="https://www.astm.org/Standards/C837.htm">methylene blue index method</a> that would make it possible for in-field clay measurement. This would optimize treatment processes, translating to cost savings and faster reclamation of the tailings ponds.</p>
<p>From helping to create reclaimable tailings to producing a bottle of quality wine, advances in clay measurement can bring many economic and environmental benefits.</p><img src="https://counter.theconversation.com/content/157840/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jason Ng receives funding from Natural Resources Canada's Clean Growth Program, Natural Sciences and Engineering Research Council of Canada (NSERC) and the Institute for Oil Sands Innovation (IOSI).</span></em></p><p class="fine-print"><em><span>Andrea Sedgwick receives funding from Natural Resources Canada"s Clean Growth Program, Natural Sciences and Engineering Research Council of Canada (NSERC), Alberta Innovates, Alberta Jobs, Economy and Innovation and the Institute for Oil Sands Innovation (IOSI).</span></em></p>
Throughout human history, clay has played a role in many different industries. Its unique properties make it suited for a wide applications in widely ranging industries.
Jason Ng, Research Associate, Oil Sands Sustainability, Northern Alberta Institute of Technology
Andrea Sedgwick, Applied Research Chair, Oil Sands Sustainability, Northern Alberta Institute of Technology
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/120580
2019-08-19T20:01:11Z
2019-08-19T20:01:11Z
How clay helped shape colonial Sydney
<figure><img src="https://images.theconversation.com/files/287822/original/file-20190813-9431-1nm17pg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A large bowl or pan thought to have been made in Sydney by the potter Thomas Ball between 1801 and 1823.</span> <span class="attribution"><span class="source">Courtesy of Casey & Lowe, photo by Russell Workman</span></span></figcaption></figure><p>In April 2020, Australia will mark 250 years since James Cook sailed into Kamay (later known as Botany Bay) on the Endeavour, kicking off a series of events that resulted in the British arriving and staying uninvited first at Warrane (Sydney Cove) in 1788, and later at numerous locations across the continent.</p>
<p>Indigenous sovereignty was never ceded, and as a nation we are still grappling with the consequences of these actions of 221 years ago. Although we often focus on the large-scale impact of British settlers – the diseases my ancestors brought, the violence they committed – we are less good at seeing the small and unwitting ways that settlers participated in British colonialism. One such story emerges when we track the history of an unlikely cultural object – clay from Sydney.</p>
<p>In April 1770, Joseph Banks – the gentleman botanist on James Cook’s first voyage – recorded in <a href="http://adc.library.usyd.edu.au/view?docId=ozlit/xml-main-texts/p00021.xml;chunk.id=d1207e10874;toc.depth=1;toc.id=d1207e10644;database=;collection=;brand=default">his journal</a> how the traditional owners of Botany Bay painted their bodies with broad strokes of white ochre, which he compared to the cross-belt of British soldiers. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-captain-cook-became-a-contested-national-symbol-96344">How Captain Cook became a contested national symbol</a>
</strong>
</em>
</p>
<hr>
<p>Eighteen years later, Arthur Phillip, Governor of New South Wales, sent Banks <a href="https://www.sl.nsw.gov.au/banks/section-07/series-37/37-08-letter-received-by-banks-from-arthur">a box full of this white ochre</a> – he’d read the published journal and suspected Banks would be interested. The ochre was a fine white clay and Phillip wondered whether it would be useful for manufacturing pottery.</p>
<p>Once in Britain, this sample of clay took on a life of its own, passed between scientists across Europe. Josiah Wedgwood – Banks’ go-to expert on all things clay-related – tested a sample and described it as <a href="http://www.jstor.org/stable/106842">“an excellent material for pottery”</a>. He had his team of skilled craftspeople make a limited number of small medallions using this Sydney clay.</p>
<p>These medallions depict an allegory according to the classical fashion of the time. A standing figure represents “Hope” (shown with an anchor) instructing three bowing figures – “Peace” (holding an olive branch), “Art” (with an artist’s palette) and “Labour” (with a sledgehammer).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/285070/original/file-20190722-134153-15dyda4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/285070/original/file-20190722-134153-15dyda4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/285070/original/file-20190722-134153-15dyda4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=619&fit=crop&dpr=1 600w, https://images.theconversation.com/files/285070/original/file-20190722-134153-15dyda4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=619&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/285070/original/file-20190722-134153-15dyda4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=619&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/285070/original/file-20190722-134153-15dyda4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=778&fit=crop&dpr=1 754w, https://images.theconversation.com/files/285070/original/file-20190722-134153-15dyda4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=778&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/285070/original/file-20190722-134153-15dyda4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=778&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Sydney Cove medallion.</span>
<span class="attribution"><span class="source">State Library of NSW</span></span>
</figcaption>
</figure>
<p>A cornucopia lies at their feet, representing the abundance that these qualities could produce in a society, while in the background a ship, town and fort suggest a flourishing urban settlement supported by trade. </p>
<p>This little ceramic disc made out of Sydney clay represented tangible evidence of how the new colony could flourish with “industry” – the right combination of knowledge, skills and effort. Yet notably absent from this vision of the new colony was any representation of Aboriginal people.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/285069/original/file-20190722-134095-ew1raw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/285069/original/file-20190722-134095-ew1raw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/285069/original/file-20190722-134095-ew1raw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=608&fit=crop&dpr=1 600w, https://images.theconversation.com/files/285069/original/file-20190722-134095-ew1raw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=608&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/285069/original/file-20190722-134095-ew1raw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=608&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/285069/original/file-20190722-134095-ew1raw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=764&fit=crop&dpr=1 754w, https://images.theconversation.com/files/285069/original/file-20190722-134095-ew1raw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=764&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/285069/original/file-20190722-134095-ew1raw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=764&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The back of the Sydney Cove medallion.</span>
<span class="attribution"><span class="source">State Library of NSW</span></span>
</figcaption>
</figure>
<p>For something only a little larger than a 50 cent piece, this medallion had a long legacy in colonial NSW. It was reproduced on the front page of <a href="https://archive.org/details/voyageofgovernor00phil_0">The Voyage of Governor Phillip to Botany Bay</a> – one of the first accounts of the fledgling colony. Later it was adapted for the <a href="https://www.environment.nsw.gov.au/Heritage/research/heraldry/firstseal.htm">Great Seal of New South Wales</a> – attached to convict pardons and land grants.</p>
<p>Later still, a version formed the first masthead of the <a href="https://trove.nla.gov.au/newspaper/page/5653">Sydney Gazette</a> – the first newspaper in the colony. The ideas behind the medallion gained even wider circulation in the colony. As historian of science <a href="https://doi.org/10.1071/HR15018">Lindy Orthia has argued</a>, the Sydney Gazette was a place where various schemes for improving manufacturing and farming were regularly discussed.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/285067/original/file-20190722-134076-17kw302.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/285067/original/file-20190722-134076-17kw302.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/285067/original/file-20190722-134076-17kw302.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=777&fit=crop&dpr=1 600w, https://images.theconversation.com/files/285067/original/file-20190722-134076-17kw302.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=777&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/285067/original/file-20190722-134076-17kw302.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=777&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/285067/original/file-20190722-134076-17kw302.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=976&fit=crop&dpr=1 754w, https://images.theconversation.com/files/285067/original/file-20190722-134076-17kw302.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=976&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/285067/original/file-20190722-134076-17kw302.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=976&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The first Great Seal of New South Wales as used on a land title deed.</span>
<span class="attribution"><span class="source">State Library of NSW</span></span>
</figcaption>
</figure>
<p>We can see the impact of these ideas by looking at what colonists themselves did with the clay. Although the first examples of Sydney-made pottery were unglazed and fragile, by the first decades of the 19th century, the quality had improved.</p>
<p>Over the last 30 years, archaeologists have found examples of Sydney-made pottery across Sydney and Parramatta on sites dating from the 1800s to 1820s.</p>
<p>Commonly called “lead-glazed pottery”, this material ranges from larger basins and pans, to more refined, decorated items, including chamber pots, bowls, plates, cups and saucers. Although basic, it clearly was based on British forms. The discovery of the former site of a <a href="http://www.caseyandlowe.com.au/site710.htm">potter’s workshop</a> in 2008 confirmed this material was made locally.</p>
<p>It has been found on sites ranging from the Governor’s residence on the corner of Bridge and Phillip Street, Sydney, to former convict huts in Parramatta, alongside imported British earthenware and Chinese export porcelain. Visitors to the fledgling colony commented on this pottery as evidence of its growth and development.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/285071/original/file-20190722-134101-taeqst.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/285071/original/file-20190722-134101-taeqst.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/285071/original/file-20190722-134101-taeqst.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=322&fit=crop&dpr=1 600w, https://images.theconversation.com/files/285071/original/file-20190722-134101-taeqst.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=322&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/285071/original/file-20190722-134101-taeqst.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=322&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/285071/original/file-20190722-134101-taeqst.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=405&fit=crop&dpr=1 754w, https://images.theconversation.com/files/285071/original/file-20190722-134101-taeqst.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=405&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/285071/original/file-20190722-134101-taeqst.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=405&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Examples of Sydney-made pottery found at an archaeological site at 15 Macquarie Street, Parramatta.</span>
<span class="attribution"><span class="source">Courtesy of Casey & Lowe, photo by Russell Workman</span></span>
</figcaption>
</figure>
<p>Sydney-made pottery helped colonists maintain different aspects of “civilised” behaviour. When imported tableware was expensive, local pottery allowed convicts living outside of barracks and other poorer settlers to use ceramic plates and cups, rather than cheaper wooden items.</p>
<p>Locally-made pots were also used to cook stews over a fire. Stews not only continued the established food practices of their British and Irish homes, but also conformed to contemporary ideas of a good, nourishing diet.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-archaeology-is-so-much-more-than-just-digging-108679">Why archaeology is so much more than just digging</a>
</strong>
</em>
</p>
<hr>
<p>These practices around food would have distinguished colonists from the local Aboriginal people. In the coastal area around Sydney, locals tended to roast meat and vegetables, and to eat some fish and smaller birds or animals after only burning off their scales, feathers and fur. </p>
<p>George Thompson, a visiting ship’s gunner who had a low opinion of most things in the colony, thought that eating half-roasted fish was evidence of <a href="https://archive.org/details/bub_gb_xsNbAAAAcAAJ/page/n62">“a lazy indolent people”</a>.</p>
<p>As historian <a href="https://trove.nla.gov.au/version/49028602">Penny Russell has discussed</a>, eating “half-cooked” food became a well-worn trope in the 19th century, frequently repeated as evidence of the supposed lack of civilisation by Aboriginal people. By contrast, as the historian and curator <a href="https://doi.org/10.1080/14490854.2012.11668429">Blake Singley has suggested</a>, European cooking methods frequently became a way that native plants and animals could be “civilised” and incorporated into settler diets.</p>
<p>The colonists’ use of Sydney clay helped to distinguish their notion of civilisation from Aboriginal culture, and so implicitly helped to justify the dispossession of Aboriginal people. The story of this clay demonstrates how quickly colonists’ focus could shift away from Aboriginal people: although Aboriginal use of white ochre continued to be recorded by colonists and visitors, Sydney clay primary became seen as the material of a skilled European craft.</p>
<p>Through the use of local pottery, ordinary settlers could participate in this civilising program, replicating the culture of their homeland. These small, everyday actions helped create a vision of Sydney that excluded Aboriginal people – despite the fact that they have continued to live in and around Sydney since 1788.</p><img src="https://counter.theconversation.com/content/120580/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nicholas Pitt is supported by an Australian Government Research Training Program (RTP) Scholarship.
While working for Casey & Lowe, Archaeology and Heritage, Nicholas was paid to undertake archaeological analysis of lead-glazed pottery from the sites 710–722 George Street, Sydney (client Inmark Pty Ltd) and 15 Macquarie Street, Parramatta (client Integral Energy).</span></em></p>
Though the Indigenous inhabitants were using white clay long before them, Sydney-made pottery helped colonists maintain different aspects of ‘civilised’ behaviour.
Nick Pitt, PhD candidate, UNSW Sydney
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/116330
2019-05-20T14:27:00Z
2019-05-20T14:27:00Z
Soil is the key to our planet’s history (and future)
<figure><img src="https://images.theconversation.com/files/275002/original/file-20190516-69195-1yg53ff.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The memories retained by soil contain countless records, including a history of human encounters with the land.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>The English language is full of phrases — from “bogged down” to “feet of clay” and “dirt cheap” — that reflect how we appreciate the diversity of soil, but value it little. </p>
<p>Soil retains a special place in many cultures. In Ireland, where I grew up, patches of what is known as “hungry ground” are thought to retain the memory of the Irish Famine in the 1800s, and you are advised to carry bread while you cross them. To poet Patrick Kavanagh, the clay of soils sealed the hopeless fate of lonely Irish bachelor farmers:</p>
<blockquote>
<p>“<a href="https://allpoetry.com/The-Great-Hunger">Clay is the word and clay is the flesh
Where the potato-gatherers like mechanised scarecrows move</a>.”</p>
</blockquote>
<p>But is soil valueless like dirt or replete with mystery? Is it just dirt, or a cathedral of evolutionary and cultural memory? Like an elder among us, soil holds records of our planet’s past and the possibilities of its future sustainability.</p>
<h2>A repository of memory</h2>
<p>Like a library, soil houses stories written from the microscopic to the landscape scale of human and evolutionary history. Our enormous recent impacts, from <a href="https://doi.org/10.1098/rstb.2013.0116">the global nitrogen cycle</a> to our use of atomic weapons, can be read as elemental and isotopic traces in soil. </p>
<p>One quarter of all the world’s biodiversity can be found in soil; it is where many <a href="https://dx.doi.org/10.3389%2Ffpls.2018.01090">plants, bacteria and fungi evolved together</a>. In many cases, plants and soil microbes established mutually beneficial relationships, communicating with each other by sending signals through the soil in a complex dating game. Butterflies and beetles and some bees, too, <a href="https://www.bumblebeeconservation.org/bumblebee-nests/">evolved to need the soil for certain stages of their life cycle</a>. </p>
<p>Soil also remembers its natural vegetation — as seeds that can be used to help restore the native plant diversity and ecosystem, <a href="https://www.theguardian.com/lifeandstyle/shortcuts/2019/apr/24/why-you-should-turn-lawn-into-wildflower-meadow">even in an urban lawn setting</a>. For plants, <a href="https://doi.org/10.1016/j.copbio.2016.01.014">the memory of their interaction with soil microbes</a> may even be transmitted to their offspring.</p>
<h2>Ecosystem services</h2>
<p>In our urgent search for solutions to climate change, we have realized soils are key to turning back the carbon clock and <a href="http://www.fao.org/soils-portal/soil-management/soil-carbon-sequestration/en/">reversing CO2 accumulation in the atmosphere</a>. Thus we are recognizing soils as far more than just an anchor for growing plants, but as the irreplaceable “skin of the Earth” providing economic, environmental and social services that are essential for life.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-soil-carbon-can-help-tackle-climate-change-116039">How soil carbon can help tackle climate change</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/274774/original/file-20190516-69178-7jlqhw.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/274774/original/file-20190516-69178-7jlqhw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/274774/original/file-20190516-69178-7jlqhw.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/274774/original/file-20190516-69178-7jlqhw.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/274774/original/file-20190516-69178-7jlqhw.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/274774/original/file-20190516-69178-7jlqhw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/274774/original/file-20190516-69178-7jlqhw.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/274774/original/file-20190516-69178-7jlqhw.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Functions of soil.</span>
<span class="attribution"><a class="source" href="http://www.fao.org/soils-2015/en/">Food and Agriculture Organization of the United Nations</a></span>
</figcaption>
</figure>
<p>Now more than ever, the science of soil reflects this appreciation of soil’s keystone role in preserving biodiversity, reversing climate change and sustaining life on Earth. </p>
<h2>Understanding soil</h2>
<p>The history of soil science has often been <a href="https://ingeniumcanada.org/channel/articles/excavating-canadian-soil-science-history">a story of international collaboration</a>, including the recent production of <a href="http://www.fao.org/global-soil-partnership/pillars-action/4-information-and-data-new/global-soil-organic-carbon-gsoc-map/en/">a global soil carbon map</a> and <a href="https://www.globalsoilbiodiversity.org/atlas-introduction">an atlas of soil biodiversity</a>, both wonderful examples of important global advances in soil science. </p>
<p>Rapid advances in application of molecular techniques are helping us understand in much greater detail the relationships between soil organisms and the many essential functions they perform. Importantly, too, we are learning much more about soil’s resilience, such as how it responds to, and may recover from, <a href="https://doi.org/10.5539/sar.v4n3p80">the stresses imposed by human activities or a changing climate</a>. </p>
<p>We are learning more about the services provided by soils in cities, and <a href="https://doi.org/10.1007/s11368-008-0023-3">the unique stresses imposed upon them</a>. According to Canadian soil scientist Henry Janzen, a fundamental goal of soil science and key to global sustainability <a href="https://doi.org/10.2136/sssaj2016.05.0143">is to extract the memories hidden in soil</a>. </p>
<h2>Managing farm soils</h2>
<p>Intensive farming systems are a major driver of land degradation and soil losses, and <a href="https://www.ipbes.net">declines in the abundance and diversity of animals and plants</a>. Applying our improved understanding of soil, an urgent challenge is to develop and support farming systems that are sustainable ecologically while also providing humanity sufficient supplies of food and fibre.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/275006/original/file-20190516-69195-xkw8k9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/275006/original/file-20190516-69195-xkw8k9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/275006/original/file-20190516-69195-xkw8k9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/275006/original/file-20190516-69195-xkw8k9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/275006/original/file-20190516-69195-xkw8k9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/275006/original/file-20190516-69195-xkw8k9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/275006/original/file-20190516-69195-xkw8k9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/275006/original/file-20190516-69195-xkw8k9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Québec farmer Sebastien Angers (standing) invites Laval University researcher Caroline Halde and French Masters intern Nathan Rondeau to assess the soil quality under a cover crop in spring 2019.</span>
<span class="attribution"><span class="source">Derek Lynch</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Farmers, as land managers, are on the front lines of this challenge. <a href="http://www.fao.org/agroecology/overview/en/">Many take an agro-ecological approach</a> and consider themselves stewards or caretakers of plant diversity and the soil as much as solely producers of crops. </p>
<p>For example, farmers who plant mixtures of flowering cover crops (buckwheat, phacelia, sweet clover, vetch etc.) benefit pollinators. The crop also protects the soil by keeping it covered over winter. As it decomposes, the abundant cover crop residue improves the soil’s structure and biological activity, while releasing nutrients to the following cash crop. </p>
<p>We need to cherish and learn from soil now more than ever. It holds the keys to our planet’s past and future.</p><img src="https://counter.theconversation.com/content/116330/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Derek Lynch receives funding for his research from the Natural Sciences and Engineering Research Council, and Agriculture and Agri-Food Canada.</span></em></p>
Understanding the different facets of soil reveals a complex and fascinating cultural and evolutionary history.
Derek Lynch, Professor of Agronomy and Agroecology, Dalhousie University
Licensed as Creative Commons – attribution, no derivatives.