72 Quicksand!-Low

QUICKSAND! FOCUS Question What can cause sand to act like a liquid?

流沙!焦点问题是什么导致沙子像液体一样?

What Is Quicksand? Think about walking on wet sand. You make footprints with each step. What if you sank into the sand? That would not be fun! You would be stuck in quicksand! When sand is soaked with water, it does not hold up your weight. Try standing along an ocean shore as the waves roll across your feet. For a moment, the sand feels like a liquid. Your feet slip lower into the sand. Then the waves roll away and the water disappears. So does the feeling of being in liquid sand. The sand feels firm again.

流沙是什么?想象一下在潮湿的沙滩上行走。 你每走一步都会留下脚印。 如果你陷进沙子里怎么办? 那可不好玩!你会被困在流沙中!当沙子被水浸泡时，它不能支撑你的重量。 试着站在海边，海浪在你脚下翻滚。 有那么一会儿，沙子感觉像液体。 你的脚在沙子里滑得更低。 然后海浪滚滚而去，水也消失了。 在液体沙子里的感觉也是如此。 沙子又变硬了。

Quicksand is a mix of sand and water. You will not find quicksand in dry places. Quicksand is usually found near the sea. Water and sand are needed to make quicksand. Quicksand forms when water from below ground moves to the ground's surface. The water pushes up into the sand. Then the sand gets "quick." In other words, it gets loose and soft It moves easily.

流沙是沙和水的混合物。 干燥的地方是找不到流沙的。 流沙通常在海边发现。 流沙的形成需要水和沙。 当水从地下流向地面时，流沙就形成了。 水向上冲进沙子里。 然后沙子变得“快”。 换句话说，它变得松散和柔软，它很容易移动。

From Marshes to Rolling Hills Quicksand can form in ground that is under or near water. It can form near rivers and beaches. It can also form near the ocean in marshes—wetlands with a lot of grass. Quicksand can also form in hilly places. Some hills have soft rocks such as limestone. Holes or tunnels in limestone let water pass through the rock. When it rains, or when snow melts, water builds up underground. The water moves up through the rock. It pushes into the ground above the limestone. This can create quicksand.

从沼泽到滚山流沙可以在水下或水边形成。 它可以在河流和海滩附近形成。 它也可以在海洋附近的沼泽中形成——有很多草的湿地。 流沙也会在丘陵地带形成。 有些山有石灰石之类的软岩石。 石灰岩中的洞或隧道可以让水穿过岩石。 下雨或雪融化时，地下就会积水。 水通过岩石向上流动。 它深入到石灰岩之上的地面。 这会产生流沙。

How Sand Acts Like a Liquid In dry sand the grains are packed together tightly. They cannot move past each other very easily. The grains rub together. This rubbing creates friction. The friction between the grains holds them together. This is why dry sand can hold heavy things. In quicksand, water gets in between sand grains and pushes them apart. Heavy objects sink into quicksand because the grains slide past one another. The sand acts like a liquid. It will act like that until the water goes away.

沙子如何像液体一样在干燥的沙子中，沙粒紧紧地挤在一起。 它们不容易从对方身边移动过去。 谷物互相摩擦。这种摩擦产生摩擦。 颗粒之间的摩擦使它们结合在一起。 这就是为什么干沙子可以承载重物的原因。 在流沙中，水进入沙粒之间并将它们分开。 重物会沉到流沙中，因为流沙的颗粒会互相滑过。 沙子就像液体一样。 它会一直这样，直到水消失。

QUICKSAND MYTHS Myth: Quicksand can suck you in. Science: Most of the people and animals that step in quicksand can get out. They are not hurt. It is nearly impossible to sink all the way into quicksand. If you stay still in quicksand, you will float in it. Myth: Quicksand is always very deep. Science: Most quicksand is only a few inches deep. It can be a few feet deep in some places. Myth: People often drown in quicksand. Science: Drowning in quicksand is very rare. If you are in deep quicksand, you can float and swim slowly to get out. If the tide is rising, however, get out as quickly as possible! Do You Know? Quicksand is common in many areas of the United States. In most places. it is very shallow—barely deep enough to make your shoes dirty.

流沙神话:流沙会把你吸进去。 科学:踏进流沙的人和动物大多数都能逃出来。 他们没有受伤。完全沉入流沙几乎是不可能的。 如果你在流沙中停留不动，你就会浮在上面。 传说:流沙总是很深的。 科学:大多数流沙只有几英寸深。 有些地方可能有几英尺深。 传说:人们经常被流沙淹死。 科学:在流沙中溺水是非常罕见的。 如果你在很深的流沙中，你可以漂浮着慢慢游出来。 但是，如果涨潮了，要尽快离开!你知道吗? 流沙在美国的许多地区都很常见。 在大多数地方。水很浅，浅到你的鞋子都不脏。