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Grab a handful and you'll see "a world in a grain of sand"
Adam Philips | New York 15 April 2010
Close up, sand grain can appear jewel-like. Indeed, many gems1, such as diamonds and sapphires2, are made from ancient sands.
Related Links
"Sand: The Never-Ending Story"
Michael Wellands's Blog
American Museum of Natural History
John Burroughs Association
Whether at the desert, on the beach or piled up at a construction site, sand is one of the most common, useful and wondrous3 materials on earth.
But what is sand? Where does it come from? How is it formed and how does it behave?
Never-Ending Story
Those are questions that prompted British geologist4 Michael Welland to write his book-length ode to the stuff, "Sand: the Never-Ending Story."
"Sand is an apparently5 mundane6 everyday material," says Welland, "and yet the journeys an individual sand grain can take you on, both physically7 and imaginatively, I found extraordinary."
Geologist Michael Welland collects sand samples in central California.
Geologist and physicists8 long ago decided9 that what makes sand sand is the size of the individual granular bits, not what they are made of. Welland notes that sand grains differ from other granular materials, both in the way they pile, and in how they behave.
"When they're flowing in the air or flowing in water, for example, they behave very differently from everything that is smaller — that's silt10 and mud — and everything that is bigger — that's gravel11 and pebbles12 and cobbles and boulders13."
Welland's book about sand earned him the prestigious14 John Burroughs Medal for natural history writing, which was presented earlier this month at New York's American Museum of Natural History. He was right at home in that august locale; sand is an important element in the beautiful old building's sparkling pink granite15 fa?ade.
'Sand: the Never-Ending Story' has garnered16 geologist Michael Welland the 2010 John Burroughs Medal for natural history writing.
A Sand Grain Is Born
"Well, what's sparkling are quartz17 grains. In a few million years, the granite of the Natural History Museum, exposed to the elements of New York, will begin to rot and disintegrate," says Welland. As the most frail18 minerals dissolve, "the quartz, which is as tough as old boots, will eventually just drop out as a sand grain."
Some of those quartz sand grains will be washed away by rainwater into nearby rivers where they will make their way down to the shoreline, and the sea or get blown to the desert. In the desert, sand grains are usually buffeted19 and shaped by the wind, which tends to make them smooth and rounded.
"The sand grains bang into each other," says Welland, "and that force tends to knock the rough edges off a grain." Desert sands are often frosted like sand blasted glass.
The beauty and variety of sand is visible in this array from South Africa, arranged by the artist Loes Modderman.
"But," says Welland "if you go to the beach where the water buffers20 the impact between grains, it takes millions and millions of years to knock their rough edges off."
In yet another kind of transformation21, grains of coastal22 sand can get squeezed together by the weight of overlying sediments23 and become rock themselves, which is how sandstone gets formed.
Welland explains that those sand stones can then be churned back up to the earth's surface by the movement of the earth's plates and then those sandstones themselves will rot.
"And so, the sand grain starts off on a second life journey. Many of the grains we see on the beach will have been through two, three, four, five of those cycles over hundreds of millions of years."
British geologist Michael Welland says sand has many uses in the modern world.
Sand families
Sand grains tend to group together in "families" according to mineral type, density24, shape, weight and other factors. The relative proportion of these groupings in any one area of beach is unique.
Sand can even be used as forensic25 evidence in criminal investigations26. For example, if the specific array of minerals in the sand found in a suspect's shoe match the stretch of beach where a murder victim is found, the owner of that shoe might be wise to call a lawyer.
Welland says sand has so many other uses that the modern world would be unrecognizable without it.
"We wouldn't have any glass or concrete, or the mobile phones or computers we have now — or they would have to work in completely different ways. Much of the world's jewelry27 would disappear. Sapphires and diamonds, for example, come from ancient deposits of sand [where] rivers have winnowed28 the minerals away."
"A World in a Grain of Sand…"
In his book "Sand: the Never-Ending Story," Michael Welland says that sand's beauty and diversity are every bit as compelling as its science.
He advises skeptics to bring a magnifying glass next time they go to the beach, grab a handful, and take a close look.
He confidently predicts that, like the mystic British poet William Blake, you'll see "a world in a grain of sand."
1 gems | |
growth; economy; management; and customer satisfaction 增长 | |
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2 sapphires | |
n.蓝宝石,钢玉宝石( sapphire的名词复数 );蔚蓝色 | |
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3 wondrous | |
adj.令人惊奇的,奇妙的;adv.惊人地;异乎寻常地;令人惊叹地 | |
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4 geologist | |
n.地质学家 | |
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5 apparently | |
adv.显然地;表面上,似乎 | |
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6 mundane | |
adj.平凡的;尘世的;宇宙的 | |
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7 physically | |
adj.物质上,体格上,身体上,按自然规律 | |
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8 physicists | |
物理学家( physicist的名词复数 ) | |
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9 decided | |
adj.决定了的,坚决的;明显的,明确的 | |
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10 silt | |
n.淤泥,淤沙,粉砂层,泥沙层;vt.使淤塞;vi.被淤塞 | |
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11 gravel | |
n.砂跞;砂砾层;结石 | |
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12 pebbles | |
[复数]鹅卵石; 沙砾; 卵石,小圆石( pebble的名词复数 ) | |
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13 boulders | |
n.卵石( boulder的名词复数 );巨砾;(受水或天气侵蚀而成的)巨石;漂砾 | |
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14 prestigious | |
adj.有威望的,有声望的,受尊敬的 | |
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15 granite | |
adj.花岗岩,花岗石 | |
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16 garnered | |
v.收集并(通常)贮藏(某物),取得,获得( garner的过去式和过去分词 ) | |
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17 quartz | |
n.石英 | |
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18 frail | |
adj.身体虚弱的;易损坏的 | |
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19 buffeted | |
反复敲打( buffet的过去式和过去分词 ); 连续猛击; 打来打去; 推来搡去 | |
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20 buffers | |
起缓冲作用的人(或物)( buffer的名词复数 ); 缓冲器; 减震器; 愚蠢老头 | |
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21 transformation | |
n.变化;改造;转变 | |
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22 coastal | |
adj.海岸的,沿海的,沿岸的 | |
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23 sediments | |
沉淀物( sediment的名词复数 ); 沉积物 | |
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24 density | |
n.密集,密度,浓度 | |
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25 forensic | |
adj.法庭的,雄辩的 | |
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26 investigations | |
(正式的)调查( investigation的名词复数 ); 侦查; 科学研究; 学术研究 | |
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27 jewelry | |
n.(jewllery)(总称)珠宝 | |
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28 winnowed | |
adj.扬净的,风选的v.扬( winnow的过去式和过去分词 );辨别;选择;除去 | |
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