Ocean Floor First Readings
1. Up Close and Personal On the Ocean’s Floor
Marine biologists take up residence
By PhillipliJ. Hilts
The new $5.5 million facility, owned by the
National Oceanic and Atmospheric Administration and operated in the U.S. Virgin
Under water, the barrier to science is not distance but time. Without such underwater habitats, marine biologists can only hook their objects of study and drag them out of the water, unable or more than a few minutes at a time to watch the animals where they live. Even with scuba gear, researchers have only 15 minutes at 120 feet before they must surface to avoid getting the bends, the curse of divers that makes the blood ‘boil’ as gases forced into it by the pressure bubbles out.
Facilities such as Aquarius break the time barrier, allowing humans to live for days on the ocean bottom— postponing the long, slow decompression needed to let the gases escape slowly before surfacing. Time in Aquarius offers an experience still so new, that even routine trips produce sights and insights that are fresh to human eyes and minds.
Recently a group of six and students allowed
a reporter to visit several times during their 10-day stay in Aquarius. Their
mission was to study the shaggy, bright walls of coral cliffs rising from the
bottom off the northwestern coast of
Over thousands of years, the corals, quarter inch long creatures that seem half rock and half animal, have built vast limestone reefs that protect islands and seashores around the world. Their cathedral like lattices serve as spawning grounds for many important fish, and ultimately, when buried, coral becomes the source of much of the world’s oil.
In recent years, corals have become a trove of potent drugs and chemicals. Now, researchers suspect, they also may provide crucial clues to the state of global climate change.
In many ways, corals are the undersea equivalent of the canaries that miners used to take with them below the earth to detect traces of poisonous gas. When the sensitive birds died, the miners knew it was time to get out of the mine. Similarly, coral reefs are so sensitive to changes in light and temperature that they may be among the first biological systems to change, or to collapse, if the world warms and the seas rise over the next 50 years, as the "greenhouse effect" theory predicts.
Currently one of the chief mysteries of
reefs is the widespread death of corals and other reef animals. In the past five years, massive die-offs have
swept across the
Ninety eight percent of the entire population
of black urchins died in one season. Few are left here at
It remains unclear whether the dieoffs are connected to a global greenhouse warming, but the possibility has spurred Aquarius biologists to undertake a wide range of basic studies of coral reef ecosystems. According to Richard Rounds of Fairleigh Dickinson, it was only recently that researchers began collecting as basic a form of data as water temperature.
In life and color, the reefs are as prolific as any acreage on Earth. They are packed with an estimated million species, the whole swarming community creating and burning up energy at a furious rate. Wherever corals can gain a foothold, they build. Their skeletons, instead of being inside their bodies, are on the outside—bony apartments in which they live. The shapes of these apartment complexes are strange and varied, and their names describe them: brain coral as a dome with grooves, the Elkhorn stands like broad antlers, the sea fan is a great lacy leaf and the deadman's fingers reach up from the bottom and undulate like a grasping hand.
But there is no margin in this life. The
corals live at their upper limit of temperature; a warming of 2 degrees
can kill them all. They soak up light
hungrily, but a little extra light, as might fall on them if ozone layer decays
enough, can scorch them. And if the sea
level rises only slightly faster than it does now, the slow building reef will be unable to
keep up. It will slowly die from lack of light. Leading scientific
team on Aquarius was Drew Harvell, a
Twice each day, the divers launched themselves from under the habitat to carry out their experiments, donning double air tanks and swimming among the unearthly shapes and colors of the corals, fish, anemones and worms. They also went out on five (nights, gliding through the water with lights to make observations.
"Until a few years ago, ecologists had no information about chemical effects in the ocean. Now we realize that they have more effect than any other single phenomenon in marine says William Fenical of Scripps Institution of Oceanography, who waited ashore to analyze coral specimens.
From the point of view of small creatures such as reef fish, the apparently placid coral reef on which they depend for sustenance is alive and threatening. "Imagine‘ a Landscape of white rock pockmarked with thousands of holes,’ wrote Eugene Kaplan in his book, “Coral Reefs." "At night, out of each hole extends a hand… . . . writhing and snapping at anything that passes by…. Visualize the hands covered with hair. To touch these hairs could mean instant death, for some are poisonous."
In the key experiments, divers collected two species of soft coral from shallow reefs and from reefs 100 feet deep. They transplanted them—shallow to deep and deep to shallow—into little artificial colonies.colonies.
The experiment is aimed at understanding the puzzling defense mechanisms of soft corals. They l stand upright, prominently displayed on the reef, seemingly a choice morsel (passing predators. Unlike hard corals, they have no stony armor, no piercing projectiles, no nasty barbs. But fish will not go near them. The reason may be important to medicine as well as to science: The corals produce an array of noxious compounds to defend themselves.
Biologists want to know whether the
production of toxins is fixed at a given rate by evolution or can vary
according to environmental factors. If
the chemical production is limited by genes, the corals should not be able to
adapt when transplanted to a different environment, such as deeper or shallower
water. If, on the other hand, the production is not fixed the animals should be able
to adapt. For example, corals that produce few toxins in deep water, where
there are few predators, should begin producing the chemicals when moved to
shallow waters where fish start nibbling at them. The transplanted corals will
rest in the canyon off
The scientists did not have to wait for results of experiment. One night, the team went out with mesh bags to find banded butterfly fish. The fish were unprepared for night visitors, and the researchers found that they could stun them simply by shining a light in their eyes. Back near the Aquarius, Nowlis put each butterfly fish into a 4by4 foot wire cage with some soft corals. What he saw was fascinating: The fish avoided eating soft corals, preferring nearly anything else. But if given nothing else, they nibbled on the less noxious ones from deeper reefs.
Nowlis other predators— in one cage the orange and black flamingo tongue, in another the bristly red and white fire worm. They too chewed up the deep water corals and avoided the shallow water ones.,
Even Aquarius cannot give the divers enough time underwater to watch as the natural of a coral reef unfolds. The corals reproduce only every few years, and then only for few hours. In one night, four days after the full moon, they commit their free-swimming larvae to the sea, to seek their own way. The next time the corals reproduce, Drew Harvell be there to watch, to collect, to study the young and how they join the life of the coral reef.
Coral in Hot Water?
5/1989 Star Bulletin
By Jan TenBruggencate
If the warming continues, it probably will result in a decline in marine life in Hawaiian waters, the researcher said.
The temperature sensitive corals could also be an indicator of the larger potential environmental problem said Paul L. Jokki, a coral researcher at the Hawaii Institute of Marine Biology.
Scientists have found that overly warm water is a primary cause of “bleaching” and sometimes the subsequent death of coral communities.
s, And they have
noted more and more of these bleachings in
Jokiel and co author L. Coles, with
the King University of Petroleum and Minerals Research
The death of reef coral is a concern for a variety of reasons, including the protection such reefs provide to the shoreline. But coral death may be even more important as an indicator of the health of the marine community, Jokiel said.
Studies show that there tends to he more marine life from shellfish to swimming fish, in areas with healthy coral communities than in areas with unhealthy or dead coral, Jokiel said. The reduction in both the diversity of species and the overall weight of the living things in a given area may be related to the decline in corals as members of the food chain and as shelter. But more, the other species decline for the same reasons that cause the coral to die off, he said.
Corals are long lived and require a high water quality, If the corals are going because of changing water conditions, you can assume other species are impacted also,” he said.
Jokiel did his initial studies in the late 1960's and
early 1970's on the effects of heated water on coral communities in the hot
water outfalls of electrical power plants.
Much of the work was done on the reefs off the Kahe
Point plant on
Then, 1O years
Jokiel said there is still not sufficient information to link the higher water temperature greenhouse effect. Most scientists agree the global warming of the greenhouse effect is coming but they disagree over whether odd worldwide weather patterns and heat of the past few years mean it’s already here. Still, a “prolonged warming trend of this intensity and duration is unprecedented in the long term record,” Jokiel said in their article for “Coral Reefs’ “
"In 1986, 1987 and 1988 Hawaiian corals were perilously close to their bleaching threshold during the summer months, and localized bleaching did occur, " he said.
Bleaching occurred in some shallow reef areas, but also in waters
as much as 60 feet deep the lee sides of the larger islands: off Olowalu,
“What we’ve had in
But Jokiel said
“Repeated annual summer bleaching of corals in the thermal (power plume) off Kahe Point did not appear to enhance their thermal resistance. The same corals continued to bleach every summer, suggesting that much longer times are needed for adaptation.
. “The possible rate of warming due to the greenhouse affect would probably occur in less than 50 years, a time frame that appears to be too short for genetic selection in long-lived reef corals,” the authors wrote in the for “Coral Reefs."
R Jokiel said the
studies of the same species of coral in
Studies of related corals in
Coral bleaching doesn’t only happen because
of heated water. Ultraviolet radiationrcan cause it, as can darkness and lower
salinity in water. But temperature
appears to be the cause of recent reports of bleaching off
.2. Antarctic Meltdown
Shackleton Camp just 300 miles from the South Pole,
it is hard to imagine
If there was a major meltdown during
the Pliocene, it could happen again. Antarctica, which is almost twice the size
So, are we headed for Waterworld ? Should we build our homes in stilts? Scientists are divided on this issue. Once camp, the “dynamists”, believes that the Antarctic ice sheet is dynamic: It has undergone rapid changes in the past and could do it again. The other camp, the “stablists”, believes that the Antarctic ice sheet is stable and unlikely to melt away in the foreseeable future. To see what evidence is being gathered to settle the debate. I flew south last year to visit members of the two factions during their field seasons.
Getting to Antarctica requires an
eight-hour flight to
After landing a McMurdo, I took a
second flight to Shackleton Camp where the dynamists team had been working for the
past two months.Stiff from the long, cold ride, I
stood up stretched, and looked through the window for any sign of life in this
foreboding, desolate land. I saw six Quonset huts, a handful of tents, and
three outhouses perched on a slab of ice in the middle of a mountain valley. Once outside, my parka rippling against the freezing wind. I
tried to imagine a land that the dynamists say once looked like the green
It all began in 1983 when Peter
Webb, a geologist at
suggested that the climate during the Pliocene may have been warm enough to
melt the ice and allow the ocean that surrounds
At first the findings were dismissed. The few scientists who gave them any thought said that the diatoms must have somehow blown into the sediment from the sea floor. It was a fluke, they said.
Back in 1983, it was generally
agreed that after
But in 1985, Webb and Harwood
Three years later, beetle remains
turned up in the rubble. With this find, Harwood and Webb's notion of a dynamic
ice sheet and climatic shifts finally grabbed the interest of a cadre of
experts. "The survival of a bettle during the
Pliocene in Antarctica implies that temperatures were significantly warmer than
present," say micropaleontologist Allan Ashworth
In the field season that ended in
1996, Harwood and Webb took further steps to investigate their theory. First,
they revisited the
It will take several years to analyze diatom populations. In the meantime, Harwood and his team are puzzling over a mosslike plant colony found at Bennett platform. Harwood says it probably grew in wetlands that were eventually covered by silt from a nearby river or stream during a glacial advance. The geology of the area, which is part of the Sirius Group, suggests that a lot of water was present when the rock face formed.
Ashworth also made a fascinating
discovery: He found seeds and sea shells in the box of rocks he brought back
from the field last year. "They're interesting in their right," he
says, because neither fossil group had previously been found on
Meanwhile, a variety of other
research has beguin to yield supportive evidence. One
study suggests that warm-blooded sea creatures, including dolphins, may have
migrated closer to
"The evidence is quite
compelling," says paleontologist Brian Huber of the Smithsonian's
As I flew by helicopter over McMurdo
Sound toward the
I land in
Marchant then strolls over to a sandy mound where he has been digging for ash with a trowel. He says that he reads the history of climate by examining how rocks weather, and where they are found. Then, for a chronological framework, he looks for nearby volcanic ash. Ash, like rocks, can reveal environmental clues through its content and current condition. And because it is the last thing to land on the surface of a formation, it can pinpoint a minimum age for the rocks.
The team has also mapped 75 ash deposits, and obtained dates for 50 of them. The samples show that the ash formed in a cold, dry environment, and remained undisturbed. It was found on rocks that are unmarked by any massive ice sheet movement.
In addition, geologist David Sugden of the
Taken together, these results speak
volumes in favor of a dry, cold, steady state. They indicate that the Pliocene
temperatures were only three to eight degrees Celsius above today's
temperatures, and that the ice sheet covering the
"We do not deny that Harwood is
finding the fossils," says Marchant. In fact, he
says, "we'd expect it." Before Antarctica split from Gondwana, it supported many of the same plants and insects
that are now found in South America and
While Harwood and Webb contend that
their miniature forest withered three million years ago,
For now, the argument remains unsettled. Though Harwoods says that both camps may eventually prove to be correct--that there was a long period of cold punctuated by relatively short bursts of heat--Marchant disagrees, say "these are mutually exclusive positions and there is no evidence for an intermediate theory."
About the only thing both camps agree on is that the key to solving this mystery is to establish, once and for all, the age of the Sirius sediment fossils. Although this will be difficult, because there is no definitive technology on which to rely, an attempt will be amde this year. An independent group of researchers will drill a core from the Sirius Group rocks to determine whether diatoms exist below the surface (and therefore are unlikely to have been windblown), or only near cracks or at the top.
Both groups recognize the urgency of
coming to a firm conclusion. The
Antarctic ice sheet affects only only global sea
level, but also world climate. So agreement on a clear picture of the past
could help to cast a more accurate vision of Earth's future. If the stablists are correct, and the eastern ice sheet remained
frozen during the Pliocene, then there is little reason to worry about the fate
of our coastal cities. A major temperature increase would be required to have
any effect. But if the dynamists are right, and the ice sheet did melt down,
then a moderate rise in the mercury could one day bring on the floods. For now,
however, the answer lies hidden in
What about the West?
the fate of
There are signs that the west Antarctic ice sheet is already breaking up. A huge iceberg broke free of the Larsen ice shelf in 1995. Shortly thereafter, a 40-mile-long crack opened in the adjoining shelf area. Now, ice streams that flow through the sheet are behaving erratically.
Last year, Stanly Jacobs of Columbia University's Lamont Donerty Earth Observatory made the first oceanographic measurements across a deep channel beneath the leading edge of Pine Island Glacier.His findings show that the west Antarctic ice sheet is losing mass to the oceans. But whether this instability is symptomatic of an impending collapse remains unknown.
To further study the current state of the west Antarctic ice sheet, and to predict its future, the National Science Foundation is sponsoring a variety of Antarctica-based research projects. For example, Cal Tech scientists at Upstream Bravo Camp are sinking ice strings and digging ice cores to study the movement of fast flowing ice streams.
They're also burying seismic monitors in snow fields to listen for "ice quakes" set off by colliding ice sheets.
Think of the Antarctic ice sheet as Earth's refrigeration unit: It exerts a major tw0-way control over today's global environment.
First, the ice sheet (along with a raft of ice that surrounds it
in the southern ocean) reflects back into space about 80 to 85 percent of the
sun that hits it. So icy
Second, the near-freezing meltwater that runs off the ice cap, along with the water from melting icebergs, falls to the ocean floor and surges northward. This surge affects deep-sea circulation, which in turn influences climate. So, a major meltdown would not only raise sea level worldwide, but cold also modify weather patterns.
For a better fix
on the details, the National Oceanic and Atmospheric Administration is
monitoring weather, ozone depletion, and long-term climate trends at the South
Pole. In addition, scientists are refining their models of the oceans and the atmsophere by studying bottom water in Antarctica's
July 19, 2002 Posted: 5:28 AM EDT (0928 GMT)
surveyed volume and area changes across
From Natalie PawelskiCNN Sci-Tech
-- A new study indicates that glaciers in
Scientists have long warned that global warming -- when heat-trapping gases force atmospheric temperatures to rise -- could eventually raise sea levels to a dangerous point by melting ice sheets and glaciers.
whole issue of global climate change is important to everyone," said
glacier expert Anthony Arendt of the
Arendt and his colleagues used a technology called laser altimetry to measure volume changes of 67 Alaskan glaciers over four decades.
"We know that the climate has had to change for that to happen," he said. "Whether or not these changes in climate are due to human influences, that's not for us to say, but it's possible that it is linked to a larger-scale change in global climate caused by human activity."
A panel of scientists that regularly reports to the United Nations on global warming issues has projected that sea level will rise between three inches and about two-and-a-half feet during this century. But glaciers melting faster than expected could increase that projection.
study found that the Alaskan glaciers were thinning enough to produce a
sea-level rise of about .14 millimeters per year -- melting almost twice as
fast as the
The survey, published in the journal Science, relied on an airborne laser and a satellite-based global positioning system to plot the glaciers' altitudes and calculate their volume. Comparisons were then made with topographic maps from years before the 1990-technology was developed, to extrapolate melting rates back to the 1950s.
The Environmental Protection Agency says the Earth's temperature has risen about 1 degree Fahrenheit during the past 100 years, most likely because of global warming.
"Human activities have altered the chemical composition of the atmosphere through the buildup of greenhouse gases – primarily carbon dioxide, methane, and nitrous oxide," says a definition posted on the EPA Web site. "The heat-trapping property of these gases is undisputed although uncertainties exist about exactly how Earth's climate responds to them."
Measuring the meltdown
Birth of New
Rising from deep within the earth is a jet of molten rock that
cuts large holes in the Pacific seabed, forming new volcanoes and eventually
whole new islands as well, its brood including Maui and
Now, scientists have descended in a submersible to probe an episode of explosive violence at the jet's leading edge accompanying the birth throes of a new Hawaiian island. Their target, a half mile down, was the summit of Loihi, which has suddenly become one of the worlds most active volcanoes.
"It's nerve-racking" Dr Alexander Malahoff, the expedition's chief scientist, said of his dives into the dark, churning waters. "The top of the volcano is a physical wreck."
In July and
August, the site was rocked by thousands of seaquakes, including the strongest ever recorded around
Land was in fact spared. But Dr. Malahoff and other scientists who dove to the craggy recesses of the undersea volcano discovered a riot of landslides, toppled rock formations and a bus-size volcanic boulders strewn over four or five miles. But this was not the result of a major eruption. The turmoil at the volcano's top had collapsed its summit, creating a murky crater more than a half-mile wide and 1000 feet deep.
This was a
He made three dives into the volcanic depths in as many days late in Sept. 1996, and the dives continued through October 1996. The team is diving in a Pisces submersible, which can carry three people down a little more than a mile and therefore is limited to exploring the volcano's summit. The whole seamount rises almost three miles from the ocean floor.
Dr. Malahoff is a director at the Hawaii Undersea Research Lab
And tricky currents posed dangers. Waters flowed into the newly formed pit, percolated through the volcano's hot interior and rushed out over a lip on the volcano's western edge. The scientists had to avoid getting sucked down by the inrush ton one side and pushed up by the out-rush of the other.
They say the tumult is part of the volcano's halting upward growth. Lava flows build it up, and avalanches and collapses and cataclysmic explosions knock it down ‘and widen it, creating a larger base for the next stage of building, Tens of thousands of years are expected to pass before the volcano's fiery summit rises above the waves. The fight is between construction and destruction.” Dr. Malahoff said at the news conference.
Avalanches are well known to have shaken the steep sides of Loihi, but no episode this violent has ever before been studied up close. Scientists say the event sheds important new light on the dynamics of island building as well as a whole range of environmental issues, like the extent to which explosive releases of volcanic gases like carbon dioxide may be contributing to the greenhouse warming of the earth. Such releases, they say, may augment human ones.
And it is
aiding overall studies of the Hawaiian jet, the earth's most dynamic zone of volcanic upheaval. Beneath the big
We think it is
rather large, as much as 200 kilometers in diameter-or about 125 miles, Dr.
James G. Moore, a geologist with the United States Geological Survey in
The great heat engine within the Earth stirs a sea of hot plastic rock that melts through the crust in places, with the vast majority of the surface action taking place in the hidden darkness of the deep sea.
In places, the interior heat gives birth to jets or plumes of hot material that are stationary in relation to the deep earth but continuously rise toward the surface. Over the eons, the Jets pierce plates that move slowly overhead, much as a blowtorch would melt holes in a steel plate moving by.
The gigantic plates that make up the earth's crust move over the jets at the rate of a few centimeters a year, or about as fast as fingernails grow.
As a result of this SLOW creep, a single jet aver the ages can leave a
Trail of extinct, progressively older volcanoes in the plate above.
Such a trail is seen the Pacific, where the Hawaiian hot spot has
formed not only the Loihi volcano but a chain of extinct ones that run west-ward
across the Pacific plate from
The bend where the Hawaiian chain turns into the Emperor chain represents a change of plate motion that occurred about 40 million years ago.
The volcanic islands are slowly pared down by landslides and sink deeper into the sea, usually leaving only the newer ones at the head of the chain above water — or struggling to break through the waves.
Loihi, which means “long one” in Hawaiian and is pronounced low-EE-hee, and is an elongated monster 13 miles wide and 25 miles long. The `Pacific sea bed on which it rests isl~3.4 miles down at its lowest point. During eruptions and outbursts over tens of thousands of years. Loihi has grown until the volcano is now more than 2.8 miles tall. Its stirrings are carefully monitored by several government agencies including the National Oceanic and Atmospheric Administration, an arm of the Commerce Department, and the United States Geological Survey, which maintains a network of seismometers on the big island. Seismometers measure faint vibrations in the ground that tell of distant earthquakes
ear~tLoihi has heaved with seaquakes before, most recently in 1991, but not
like this summers torrent of violence. The quakes prompted Harry Kim, the Civil
Defense director of
Island residents are used to coping with threats of tidal waves generated by distant earthquakes far across the ocean, but not local ones.
To better understand what was happening and, in part, to help develop ways to predict and warn of future dangers, Dr. Malahoff and his team dove into the depths.
"Eventually something will happen," he said of disasters on land touched by the deep volcano, " but maybe not in our lifetimes.”
In trying to
unravel the mystery of the deep upheaval, the team early on monitored the violence with microphones suspended from
buoys and detected cracklings that sounded like the flow of deep lava. But submersible probings
of the northern
What the team did discover, based on a comparison with older observations, was that a huge part of the volcanoes summit had collapsed in the frenzy of destruction. "Nobody,"“ Dr. Malahoff said. “has ever observed the formation of these pitcraters.”
The collapse of the summit probably look two or three days, he said, and its slowness was a godsend.. A quick collapse would have generated. a huge tsunami, or tidal wave. A likely possibility, he said, is that he slow collapse was provoked when the hot lava from the volcano’s interior oozed out of its flanks at a depth somewhere below the region where the Pisces submersible could explore.
ex’ 1 In the most dangerous moment of the series of dives, Dr. Malahoff and two colleagues ventured down to bottom of the new crater past fractured walls of towering rocks that were threatening to fall.. Later, at the crater’s bottom 1,000 feet the summit, the anxious team in the submersible, heard the rumble of a distant landslide.
At the base of the huge cliff, the team found a big vent belching hot water and clouds of microbial snow in the area around the vent painted with orange and red—and flapping lettucelike leaves of bacterial slime.
Mapping the Ocean Floor4
NOAA 95-68 10/23/95 STUNNING NEW SEAFLOOR MAP RELEASED BY NOAA
"We have known more about the topography of Venus, Mars, and the Moon than the bottom of our own oceans - until today," said Dr. Walter Smith of the Commerce Department's National Oceanic and Atmospheric Administration as he introduced a stunning new map of ocean floor structures. Using satellite sensor data recently declassified by the Navy in combination with data from the European Space Agency, Smith and his colleague, Professor David Sandwell of the Scripps Institution of Oceanography, have generated a computer model of the seafloor in unprecedented detail. The new map, which infers seafloor features from changes in the strength of gravity, provides the first detailed view of ocean floor structures in many remote areas of the Earth.
Marine geologists have been mapping the ocean floors for some time but, because of limited quality and coverage of the available data, they have had to use guesswork. Until now, the most common method of mapping the seafloor has been acoustic echo sounder readings taken by ships; only a small fraction of the sea floor has been charted, and in some remote parts of the oceans there are gaps between charted areas the size of Kansas. Much of the available data is also low tech, and inaccurately navigated. Even using the most advanced technologies available today, it would take over 125 years to chart the ocean basins using acoustic devices on ships.
The newly declassified satellite data have a survey track every three miles, and so scientists can be confident that any feature six miles across will not be missed. Another benefit of mapping the ocean floor via satellite is that the features detected are located with great precision. With this data it may be possible to answer questions like: Is there an uncharted island somewhere where Amelia Earhardt could have landed? Are there uncharted shallow banks that could be rich with marine life and exploitable by commercial fishing? (We already know the answer to that one is Yes.) Are there sedimentary basins that might have petroleum reserves that we haven't mapped yet?
The data used to generate the new map was gathered by the U.S. Navy's GEOSAT spacecraft between March 31, 1985, and October 30, 1986. As the satellite orbited the Earth almost 500 miles up in space, a radar altimeter on board returned readings of the distance from the satellite to the ocean surface accurate to about one inch. The radar waves were reflected by the ocean surface and did not penetrate it, unlike the sound waves of an echosounder, so that the satellite data yield measurements of the shape of the ocean surface, not the ocean floor. However, Smith and his colleagues at NOAA and Scripps have worked out a method for exploring the ocean floors using these data. They first use the satellite data to find tiny changes in the pull of the Earth's gravity field, and then use those gravity anomalies to infer the topography of the ocean floor.
"If I had to choose one thing as being most revolutionary about this map, I would say it is the view it gives us of the fracture zones," said Smith. In the process of seafloor spreading that causes continental drift, scars are made on the ocean floors called fracture zones that record the history of plate motion. These are used to reconstruct the ancient positions of the continents. Such knowledge can be extremely valuable in minerals exploration and in the study of climate change.
The scientific value of these data was anticipated even as the satellite was flying, and many people have worked a long time to get the data declassified. While a senator, Vice President Gore started a group called the Environmental Task Force, to seek answers to this question: are there technologies and data sets which, because of their military value, are classified, but which would have even greater value to the scientific community and the civilian economy if they could be released? This release of data set is one result of this exercise.
Although the work to
declassify the data is done, NOAA's work with the
data is really only now beginning, as it is now possible to derive data
products that can be distributed to scientific, educational and commercial
users. The raw data representing the spacecraft's measurement of ocean surface
heights is now available from NOAA's
Cool Science Facts
Current technology does not allow us to burrow through the Earth. The rock and metal thousands of kilometers below our feet are so inaccessible that they might as well be on another planet.
Believe it or not, the Earth's solid iron-nickel core helps make life possible. The solid portion of the metal core spins inside the liquid portion, making the planet act like a giant generator. The rotation creates the magnetic field which, among other things, makes compass needles point north and helps create Earth's magnetosphere. The magnetosphere and the lower atmosphere work together to protect us from some of the Sun's most dangerous particles.
Every 2,000 - 10,000 years, the Earth's magnetic field reverses. The field leaves a magnetic "imprint" on crustal rocks, as particles within the rocks align themselves according to the field. Different layers of rocks in a formation will have particles aligned differently, depending on the alignment of the poles when the rocks formed. Many scientists think that the Earth's poles may reverse again within the next one hundred years. Within your lifetime, compass needles may point south instead of north. Although this won't be directly harmful to the human population, it may be confusing for many boy scouts, not to mention navigators in planes and ships. How do yo u think this event will affect your life? Some birds and fish use the Earth's magnetic field to navigate their migration. How do you think they will be affected?
1. How much did Aquarius cost?
2. How long do divers have to study the bottom at 120 feet?
3. Why so short a time?
4. What clues are found in the coral?
5. What happened to the black urchin population?
6. How does "dead man's fingers" get its name?
7. What abiotic components can kill coral?
8. What changes on the coral reef at night?
9. What do corals produce for defense?
10. Which corals did the caged butterfly fish eat?
11. When do corals reproduce?
CORAL IN HOT WATER
12. What does warm water do to the corals?
13. Where do these bleachings occur?
14. What does the death of reef coral indicate?
15. During which year in
16. Why, with the lower temperature of the waters
17. How much higher is the leeching threshold of
18. Besides temperature, what may be causing coral bleaching?
19. What is the main idea of this article
2 Antarctic Meltdown by Beth Livermore Popular Science Feb, ‘97
1. What percentage of the Antarctic is covered by an ice sheet?
How thick is the ice sheet?
2. What living organisms have been found on this ice sheet continent?
3. When, in the past, could the Antarctic had a temperate climate?
4. How is the Antarctic ice sheet divided?
5. To what structure is the western ice sheet attached?
6.To what structure is the eastern ice sheet attached?
7. How big is the Antarctic land mass?
8 How much ice and freshwater is there on the continent? 1)
2// 9. What do the "dynamists" believe?
10. What do the "stabiists" believe?
11. What evidence was found that indicated the Antarctic climate was warmer?
12. What other evidence was found to indicate that the Antarctic was warm in the
last 3 million years?
13. Where is there no ice or snow in the Antarctic?
Why do we think that the Antarctic was once connected to South America and
15. What does the Antarctic Ice Sheet affect?
16. What is the main idea of the article about the Alaskan Ice
1. How much lava does the Hawaiian opening(jet) produce each year?
2. How long has the “Hawaiian jet” been producing lava ?
What is the name of the new
5. What happened to “Pete’s Dome’?
6. How high is this new “ to be” island?
7. What two volcanoes are powered by the Hawaiian jet?
8. What is the comparison used in this article about crustal movement and a common similarity?
9. How big is Loihi?
Why have recent earthquakes on Loihi caused concern
on the big
11. What is the main idea of this article
1. What does this new map use to map the ocean floor?
2. Why is this a better method than echosounding?
3. How long will it take to map the sea using echosounding?
4. How small of an area can this new method pinpoint?
5. Explain how scientists use the radar wave data?
6. Where is the flattest stretch of solid surface on earth?
7. What angle do continental slopes usually reach?
8. How tall is
9. What causes the earth’s magnetic field?
10. What happens to this field (9) every 2,000-10,000 years?
11. How would this (10) effect new layers of rock?
12. What is the main idea of this article