课堂英语

听力入门英语演讲VOA慢速英语美文听力教程英语新闻名校课程听力节目影视听力英语视频

英语煎蛋小学堂视频百科111:为啥哪里的沙子都一个样(MP3+中英双语)

cocotang 于2015-06-26发布 l 已有人浏览
增大字体 减小字体
英语视频:煎蛋小学堂111:为啥哪里的沙子都一个样,以幽默诙谐的方式为你解答那些那些你意想不到的科学小知识,含有中英双语字幕视频,mp3下载。
    小E英语欢迎您,请点击播放按钮开始播放……

Sand,whether you use it for building sand castles,telling time with an hourglass,Or hydraulic fracturing,is pretty much the same just about anywhere you go an uncountable number of tiny grains mixed together to from the same dunes and beaches.But why does sand almost always look the same?And how does so much of it end up at the beach?

沙子嘛 无论是搭沙堡 用沙漏计时 还是做水力破碎时 无论你在哪 沙子在哪 沙子差不多都一个样 无数沙粒聚在一起 形成同样的沙丘和海滩,不过 为什么哪里的沙子看上去都一样.

Well,much of the world's sand is made out of the same stuff tiny crystals of the mineral quartz,which is made out of silicon and oxygen,the two most common elements in Earth's crust.And as you'll know if you've ever bitten through the crust-of a sandwich that had sand in it-quartz grains are small,and really tough.

另外为何这么多最后都留在了海滩上,世界上大多数沙子都由同一种物质构成,即矿物石英的细小晶体,它由地壳中最常见的两种元素,硅和氧构成,如果曾经吃到过沙子你就知道,就比如有沙子的沙明治 石英颗粒很小但很硬.

Here's why:Quartz crystals form within a cooling blob of molten granite rock,or magma,deep under Earth's surface.As the magma cools,different minerals crystallize into solid rock at different temperatures,and quartz is one of the last minerals to form.It's forced to crystallize in the tiny spaces left in the now cooling rock,pretty much ensuring that it ends up in a specific size range.

原因在此石英结晶是在花岗岩岩浆 或者地底深处,岩浆冷却时形成的 当熔岩冷却时,不同的矿物在不同的温度结晶成为坚石,石英是最后成型的矿物之一,它被迫在冷岩的狭缝中结晶,这也使其颗粒大小被限制在一个特定的范围.

But being last has lasting advantages.Minerals that do form in the earlier,hotter conditions have weaker chemical structures and weather away more easily than quartz,kind of like how a relationship forged in the heat of passion might not be as stable as a deep bond developed over time.So as the weak,flash-in-the-pan minerals wear away,the unfaltering quartz grains are left to pop out of the rock as sand!

但最后结晶有最后的好处,在更早更热环境下成型的岩石,化学结构更不牢固比石英更易风化,这也正像秀恩爱分得快,当昙花一现的脆弱岩石消逝时,坚硬的石英砂从岩石中跑出来,成为沙子.

And then it's only a matter of time-sometimes a very long time before the quartz sand gets whisked away by streams and rivers and carried to the sea,There,at the mouth of a river,the fast-flowing water slows abruptly,and the well-rounded sand drops out.Larger rocks and pebbles were already left behind upstream,while smaller sediments like silt and clay continue to be swept along by the weakened current and are deposited further from shore.140

剩下的就是时间问题,石英砂顺江河而下来到大海需要很长一段时间,在河口处湍急的河水流速突然减缓,沙子便沉积下来,较大的岩石和鹅卵石留在了上游,较小的沉积物,如粉砂的黏土继续被缓流带到远方,并沉积在离海岸更远的地方.

Over thousands and thousands of years,the paths of rivers sweep up and down the coast,dropping off piles of sand to be spread by waves and currents into smooth sandy beaches.

数千年来,河流的路,径扫过海岸各处,将成堆的沙子送到海岸,成为沙滩,任凭波涛浪打.

Of course,not all beaches are purely quartz sand,and not all quartz ends up on beaches-but the fact that so many beaches and so many sands are the same is a testament to the chemistry of the most common components of earth's crust as they cool and crystallize,and to the physics of sediments slowly shifting and surging towards the sea.They are,quite literally,the sands of time.

 1 2 下一页

分享到

添加到收藏

英语视频排行