Exploring the Last Frontier*

Humans have climbed Mount Everest.  They have crossed the Sahara Desert and even lived at the South Pole.  But one place on earth that remains unconquered is the floor of the ocean.  Scientists know more about the moon and Mars than they do about the bottom of the sea.  The ocean abyss is truly Earth's last great frontier.  Do you wonder why it hasn't been explored? 

Just how deep is the ocean?  On average, it is about 2.3 miles deep.  But some places are much deeper than that.  The Mariana Trench lies under the Pacific Ocean.  It is a 1,584 mile-long crevasse, or deep crack, in the ocean floor.  The deepest part of the trench is called Challenger Deep.  At more than 36,000 feet down, it is the deepest spot in the world.  That's a depth of nearly seven miles--a mile and a half deeper than Mount Everest is high.   Highlight important words and make sure you know their meaning. 

People once thought that the ocean floor was flat and dull.  Now they know better: the bottom of the ocean is much rougher than dry land.  It has huge canyons, some of which are deep enough and large enough to hide the Rocky Mountains.  The ocean floor also has its own mountain ranges.  They are massive; one such range is more than 31,000 miles long.  Circling the globe, it makes its way through all four of the world's oceans. How do you think scientists measured that range?

Can you describe what you learned about the ocean so far in a short sentence?

The ocean has kept its secrets well.  In some ways, it is harder to explore the seas than to explore outer space.  One reason is that a human being, without help, can dive down only about 10 feet. Beyond that depth, pressure starts to build on the lungs and inner ear.  Do you have any idea what that pressure might feel like?  In any case, even the best diver can't hold his or her breath longer than two or three minutes.

Today, of course, divers can go much deeper than ever before.  Those who use scuba gear can go down more than 100 feet.  Scuba divers rarely go below 150 feet, though, for there is too much pressure.  Coming back can cause the bends.  A bad case can be fatal. Wearing a pressurized suit, however, a diver can go down about 1,400 feet.  From that point to the deepest part of the ocean is still a long distance. Do you think it takes a lot of training to become a diver?  Stop and record:  pressure, bends, and fatal.

In 1960, Donald Walsh and Jacques Piccard climbed into a small metal sphere. It was a bathyscaphe--a watertight cabin used for deep-sea diving.  Named the Trieste, the cabin carried nothing but the two men.  It has no cameras to take pictures or arms to collect objects.  The question was simple:  could the two men go to the bottom of the Mariana Trench and come back alive?

It took Walsh and Piccard an hour and a half to descend 10,000 feet.  Two hours later, they had gone down 32,000 feet.  Pressure at this depth was immense--almost 14,000 pounds per square inch.  After another hour, Walsh and Piccard were just 250 feet from the bottom of the ocean.  Very slowly, they dropped down to the ocean floor.  They had made it.

That event happened a long time ago.  Science has made great progress since then.  Yet no one has ever duplicated Walsh"s and Piccard's feat.  No one has even come close.  The reason is money--the trips are too costly.  What would make the trip too costly? Stop and Record:  Costly to explore.

In addition, some people aren't sure that exploring the ocean is worth the effort.  Robert Ballard is the scientist who found the wreck of the Titanic.  "I believed that the deep sea has very little to offer," he says.  "I don't see the future there."

Jean Jarry, a top French ocean scientist, agrees. He doesn't feel that people should go below 20,000 feet.  Only about 3 percent of the ocean is deeper than that.  "To go beyond that is not very interesting and is very expensive,"  Jarry says.

Others, however, disagree.  Greg Stone, of the New England Aquarium, wants to go all the way down.  He says, "We won't know what the ocean floor holds until we've been there." Stop and List pros/cons of exploring.

Do you think the author should have given more detail about why these people were in favor of or against exploration?

The Japanese also want to explore the ocean abyss.  In 1995, they sent an unmanned ocean probe named Kaiko to the bottom of Challenger Deep.   Kaiko sent back pictures of things that were hard to believe--animals able to live at that depth.  When they were there, Walsh and Piccard said they had seen a fish, but at the time few people believed them.  Most people felt that nothing could live at such a depth.  But now there is information that such life is possible.  Why would knowing that "life is possible" make it worth the cost and danger of exploring the depths of the ocean?  Stop and write a brief summary using the words and notes  you highlighted or recorded.

*Color Coding Key:  Pink: Purpose, Blue: Organization, Green: Knowledge Building, Purple: Elaboration, Red: Stop & Record

Copied with permission. Fry, E. B. Reading Drills, Middle Level, NY McGraw-Hill (2000) with SPOKES modifications.