Quicksand. Nature Lesson #14

Transcription

1 Quicksand Nature Lesson #14 1 1

2 Jack Pickett and his friend Fred Stahl, both college students, decided to spend the day looking for parasitic plants in the swampland south of Florida's Lake Okeechobee. Pickett was in the lead walking along the sandy bank of a small stream when suddenly his feet disappeared into the sand. It s soft here! Stay back! he warned his friend. 2 2

3 The ground seemed to swallow him up and he was quickly chest deep in thick muck. The sand pinned his arms to his body as he struggled to release the heavy pack on his back that was dragging him down. It s quicksand! he shouted, Help me! 3 3

4 Desperate to assist his friend, but fearing getting trapped himself, Stahl searched for a tree branch to extend his reach. Finding one, he held it out. Pickett couldn't free his hands to grab the limb and sank deeper and deeper into the sand until he simply disappeared 4 4

5 WayneTD_flickr 5 5

6 drewnaustin_flickr 6 6

7 Eva Funderburgh_flickr 7 7

8 What Is Quicksand? 8 8

9 Quicksand is formed when regular sand, mud or even gravel comes in contact with a flowing water source, usually an underground stream or spring. Under normal conditions the tiny grains in sand or other material will rub up together with enough force, or friction, to support the weight of someone or something on top of it. You can see this when you go to the beach. Even in loose, dry sand your foot only sinks a couple of inches before the friction between the sand grains grows high enough to stop you from going down any deeper. What if the something lessens the friction between the sand particles? Would you go down further? 9 9

10 This lessening of the friction is exactly what happens in quicksand. The flowing water moves between the particles of sand and acts as a lubricant to reduce the friction. The grains become suspended in the water and the sand changes to a liquefied state. As long as the water keeps flowing, the quicksand bed will exist

11 Quicksand at the Beach 11 11

12 johnthurm_flickr 12 12

13 Small patches of quicksand appear at the edge of almost every beach as the incoming waves force seawater in among the sand particles at the waterline. That s why if you stand in the surf you can feel your feet sinking into the sand a little bit more with each new wave. Fortunately, this kind of quicksand is rarely dangerous. The action of the waves only creates a quicksand patch a few inches deep, not enough to trap even a child

14 Quicksand that forms in a patch more that a few inches deep, however, can be dangerous. Typically, despite stories about quicksand beds with bottomless pits, most quicksand is only waist deep. The biggest danger an adult faces in such a pit is getting stuck and not being able to climb out by himself. If he is alone, he can face death from starvation or exposure to the cold. In some wilderness areas people trapped and unable to defend themselves have been mauled by animals such as bears or wolves. For this reason it is never a good idea to go hiking alone, especially in areas where quicksand is known to exist

15 You Don t Have to Worry about Sand Dunes 15 15

16 David Stanley_flickr 16 16

17 Places with a lot of water may often have areas of quicksand: marshes, rivers, creeks, seashores and swamps can all have pools. Places with underground sources of water like the Colorado Mountains and parts of Texas and Utah can also generate quicksand beds. One place quicksand is almost never found is the desert. Deserts have plenty of sand, but without water quicksand cannot form

18 It is often difficult to spot a pool of quicksand before walking into it. Leaves and sticks can lie on the top, concealing the pit. A crust of dried sand can form on the top hiding the liquefied material below until some steps on it and falls through. Quicksand can also form underwater and can snag people or animals as they attempt to cross rivers or walk along the edge of ocean or lakes. In these situations drowning is a strong possibility

19 19 fourninefour_flickr 19

20 Tidal flats can be particularly dangerous. In one unfortunate case in September of 1988 a woman in Alaska got caught in the mud flats near Turnagain. Adeana Dickinson and her husband were using an ATV to cross the flats when the trailer they were towing got stuck. She hoped off the back to push it out and her legs got caught in the mud. The patch she was stuck in was not light sand but powered rock, making the material particularly heavy. Her husband worked for two hours and managed to free one leg before the tide started coming in. Emergency rescue was called and a team worked to free her, but was forced to back off and watch her drown as the sea rose around them

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22 Should you fall into a patch of quicksand the first thing to remember is not to panic. Thrashing about can get you more stuck. Quicksand is a lot denser than water and a person will float much more easily than in a pure liquid. It is important, however, to quickly get rid of any weight you are carrying (like a backpack) that might drag you down. While deep pits of quicksand do exist, most are fairly shallow and you should be able to touch bottom

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24 If you cannot touch bottom it may be difficult to extract yourself without help if you have nothing solid to push against. The quicksand flows around legs and arms and trying to pull them out creates suction. The best method to get out of a quicksand bed if you can't push against solid ground or have somebody pull you out with a rope is to try swimming out with slow, deliberate motions

25 A scientist with the U.S. Geology Survey once fell into quicksand while exploring the Colorado River. Unassisted he slowly swam through the thick mud to solid land. It took him eight hours to move just ten feet, but he was able to walk away from the experience uninjured

26 Occasionally unusual conditions can liquefy the ground that was solid a few minutes before. In the 1800 s a Kansas Pacific Railroad train fell into a quicksand creek bed during a flood. While some of the cars were recovered, the 200-ton engine sank so deeply into the liquefied ground that it was never seen again

27 How to get out Remain Calm: If you step into a patch of quicksand, panic is your worst enemy. Shed Excess Weight: Just as if you were getting ready for a swim, shuck off your pack or remove your heavy jacket

28 Keep as Still as Possible until Your Feet Touch Solid Ground: Most patches of quicksand are only knee deep. If you start going deeper than your thighs, lay back so that you will float better on the top of the quicksand

29 Swim out with Slow, Deliberate Motions: This is very hard work and extracting yourself from a large patch of quicksand can take hours. Work Toward the Last Known Bit of Solid Ground: Sometimes there may be a crust of solid ground over a patch of quicksand, so you may have walked over this before going into the quicksand

30 Pull Yourself Out: Once you ve reached solid ground, pull yourself out of the mess

31 Tips Remember, quicksand behaves a lot like water. You float in water unless you re carrying something heavy or are trying to sink. Quicksand is thicker that water and is therefore easier to float in. Quicksand is also harder to swim in than water. Be very patient when freeing yourself from quicksand. Make sure that you rest if time allows