72 Quicksand!-Low

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

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.

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.

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.

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.

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.