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  • Squeaks and I live right near a river.

  • It's fun to watch the water rush past, and sometimes people even go fishing in it!

  • Like most of the rivers in the world, it flows downhill, right along the ground.

  • But did you know that some rivers flow right off of cliffs?

  • Just look at this one!

  • This is a river that's flowing right off a cliff, and that's what we call a waterfall.

  • This waterfall is called Angel Falls.

  • It's in Venezuela, in South America, and it's the tallest waterfall in the world!

  • It's almost 1000 meters tall.

  • That's taller than the tallest building!

  • Waterfalls start off as normal rivers, with lots of water flowing towards one place.

  • But then the water in the river comes to a cliff.

  • It flows over the side and becomes a waterfall!

  • In the case of Angel Falls, it becomes a huge waterfall.

  • But the cliff hasn't always been there.

  • The river actually built the cliff.

  • [Squeaks squeaks]

  • No, really!

  • Where there's now a huge cliff?

  • That used to just be regular flat ground with the river flowing over it.

  • But if you looked underneath this river, you'd find a layer of hard rock, then a layer of

  • softer rock or dirt, then another layer of hard rock, over and over in a pattern!

  • It looks almost like a cake with lots of layers!

  • Some of the parts of the river hit only the hard layers, but the water eventually hits

  • some of the softer layers.

  • That's where the water can do some real work.

  • When water goes over rocks, it can wear away at those rocks over time.

  • We call this erosion.

  • It's easier to for the water to erode soft things than hard things, like how it's easy

  • for you to smash a sand castle, but harder for you to break a brick.

  • So, as the water goes over the hard rock, it doesn't do too much.

  • But as it goes over the soft rock, it wears away the layer of soft rock more quickly.

  • The water takes a few little pieces of rock away, then a few more, and more, until finally,

  • the soft rock layer is gone.

  • When the layer of soft rock is completely eroded away, that creates a cliff between

  • two of the layers of hard rock.

  • This takes a very, very long time to happen, sometimes millions of years.

  • [Squeaks squeaks]

  • Exactly!

  • The water flows over the top of the cliff and falls straight down as a waterfall.

  • Angel Falls has grown especially tall because of how the water and the rock interact.

  • The land around Angel Falls has layers of very soft rock that erode super easily, and

  • tons of incredibly hard rock that hardly erodes at all.

  • Because of the big difference in how these layers erode, this river has carved a huge

  • amount of soft rock out of the way, and very little hard rock.

  • That created the tallest waterfall in the whole world!

  • Thanks for joining us on SciShow Kids!

  • Do you have questions about waterfalls, erosion, or anything else?

  • Have a grown-up help you leave a comment, or send us an email at kids@scishow.com.

  • We'll see you next time, here at the fort!

Squeaks and I live right near a river.

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B1 中級 美國腔

世界上最高的瀑布! |儿童地质学(The Tallest Waterfall in the World! | Geology for Kids)

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    joey joey 發佈於 2021 年 05 月 09 日
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