Page 18 - 2006 DT 12 Issues

Quicksand! ing earthquakes, not too much. on you. They might pull you “into two
pieces if [they] try hard to pull [you]
It’s all a matter of physics. Be-
cause the human body is less dense out,” said Daniel Bonn, a physics pro-
s the story goes, on a dark than quicksand, it cannot sink (at fessor at the Van der Waals-Zeeman
and stormy night in La Porte, least not like in the movies, where the Institute at the University of Amster-
AIndiana several workers from villain disappears beneath the mud). dam. “The way to do it is to wriggle
the West Michigan Railroad watched According to a study published in the your legs around. This creates a space
in horror as a train engine and several British journal Nature in December, between the legs and the quicksand,
boxcars crossed Lily Lake and slowly 2004, it is impossible for a person through which water can flow down
sank, never to be seen again. Fortu- immersed in quicksand to be drawn to dilate [loosen] the sand. You can
nately, no one was hurt. Some say the completely under. You can more easily get out using this technique, if you do
marsh over which the track had been float on quicksand than in water—but it slowly and progressively.”
laid had a quicksand bottom. Others there are some caveats. Most patches of quicksand are
say that divers have actually seen the The ratio of soil to water de- rarely more than a few feet deep, but
engine and cars that will never be re- termines buoyancy; therefore, some falling in head first could be lethal. (Try
covered from the quicksand. not to get stuck at low tide on a beach,
No one will ever know for either.) Heat exhaustion, unfriendly
sure because the marsh has animals and other elemental hazards
long since been filled in. are dangerous, too, once you’re in the
What exactly is quick- muck. While most quicksand lore is
sand? According to the just myth, don’t write it off completely
United States Geological just yet. Read on . . . .
Survey, it’s nothing more Surely you’ve heard tales of
than a soupy mixture of travelers, vehicles and even whole
sand and water. It can form caravans suddenly vanishing into the
anywhere underground wa- sands. (Hollywood has thrived on them
ter rises up to over-saturate for years). Until recently, such stories
or liquefy an area of sand, were considered mere folklore. The
silt, clay or any other grainy truth, however, may lie in “dry quick-
soil, causing the grains to become quicksands may be more difficult to sand,” described as a mysterious, more
more buoyant. In this semi-liquid state, deal with. A heavy backpack will make sinister, and potentially more danger-
the sand shifts very easily and quickly, you less buoyant, so a quick-release ous, form of quicksand which has the
thus the name. Just how quickly can buckle is important. And don’t panic. ability to quickly engulf anything that
often be seen during an earthquake in Even objects more dense than quick- crosses its surface. While such a phe-
areas where deep, sandy soils aren’t sand won’t sink until they start to move nomenon has not yet been confirmed
supported by bedrock. All that shak- around. Flailing arms and legs won’t in nature, rheologist Detlef Lohse, who
ing can increase groundwater pressure sink you, but can lock you in tighter. studies the deformation and flow of
forcing it to the surface, quickly lique- Movement causes the apparent viscos- matter at the University of Twente in
fying the ground and causing buildings ity (flow resistance) to increase as you Enschede, Netherlands, has succeeded
on top of it to sink. move, creating more vacuum on your in creating it in the laboratory.
Quicksand occurs in all 50 states. submerged half. It’s best to relax, float Dry quicksand is loose sand
You’ll find it on riverbanks, in marshes, on your back and slowly paddle your whose bulk density is reduced by
in beach areas and even in the desert way out. blowing air through it so that it yields
where underground springs flow. How If you are in above your waist, easily to surface weight or pressure.
concerned should you be? Except dur- however, don’t ask your friends to tug What water is to normal quicksand, air
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