MUD STUDY TO TRACE EVOLUTION
Sediment from sea-depths reveal secrets of Earth's changes
ATLANTIC CITY, (New Jersey): Drilling thousands of feet into the ocean’s floor, an international team of scientists reaching back tens of millions of years to learn more about the planet’s evolution.
The mud is the medium. Aboard this converted oil-drilling vessel stationed at the edge of the continental shelf, researchers are pulling samples of mud from as deep as 4,300 feet (1,311m) below the ocean floor to record the rise and fall of sea level over the past 50 million years.
Breaks in the mud, which signify a change in sea level, also reveal past episodes of global warming when giant ice sheets melted, causing oceans to rise, the researchers say.
"The Jersey shore is a natural laboratory of the Earth’s own rhythms," said Gregory Mountain, a Columbia University geologist who directs the project with Ken Miller of Rutgers University.
"If the sediments can tell us how sea levels have changed naturally over the millennia, we’ll be better able to understand future changes, both natural and man-made," Mountain said.
"We’ll be able to deal more intelligently with the complex range of effects that global warming may have on shorelines around the world."
While the international team drills offshore, the United States Geological Survey is drilling at three New Jersey coastal sites —Island Beach State Park, Atlantic City and Cape May —to get a larger picture of "what happened on the New Jersey coastal plain since the dinosaurs died," Rutgers geologist Jim Browning said.
On a recent day at a drilling site about 90 miles (145km) east of Atlantic City, scientists were withdrawing samples of sediment from 2,100 feet (640m) — and 35 million years —below the bottom of the sea. The ocean floor there is at a depth of 1,452 feet (2,337m).
The project’s 25 scientists and 85 support personnel work around the clock to examine nearly all the grayish muck recovered during the 40 days of drilling time allotted them.
Texas A and M oceanographer Steve Gartner was disappointed with the lack of fossils found in the day’s catch. Fossils provide the simplest method of dating the ancient soil, he said.
"It’s not going real well today," Gartner said during a rest in the vessel’s science lounge.
The high-tech JOIDES Resolution has been sailing the world’s seas since 1985 as part of the Ocean Drilling Program run by Texas A and M University. JOIDES stands for Joint Oceanographic Institute for Deep Earth Sampling, an advisory board of scientists from 19 member countries.
Sixty per cent of the programmes’s US$42 million yearly cost is paid by US taxpayers through the National Science Foundation. Other countries involved in the projects contribute the other 40 per cent.
The US$150 million vessel — 470 feet (143m) long and 70 feet (21m) wide with a derrick 216 feet (66m) above the waterline — has logged 169,415 nautical miles (one nautical mile is 1,852 metres) during that time, Capt Ed Oonk of Enschede, Holland, said.
It also has recovered more than 232,545 feet (70,880m) of sediment and rocks from 903 drilled holes, according to drilling operations supervisor Glenn Foss.
A computer-controlled ‘dynamic positioning system’ uses 12 thrusters to keep the ship nearly stationary without anchoring as drilling tubes bore deep into the earth.
"Few ships in the world have this," Ray Frank, who operates the system, said.
The ship has 12 sophisticated laboratories on seven levels for the study of sedimentology, paleontology, petrology, geochemistry, geophysics, paleomagnetics and physical properties.
A machine that looks like an iron lung measures the magnetic direction of the mud to record historic reversals of the Earth’s magnetic field.
In the chemistry lab, researchers continually test the sediment for hydrocarbons — gases that if released in large amounts, could thin the ocean water, reduce its buoyancy and risk sinking the vessel.
Before the Resolution leaves the area, the drilled holes will be plugged with concrete to prevent leakage of any damaging hydrocarbons, staff superintendent Pat Thompson said.
Miller hopes to repeat the research in other parts of the world to discover whether the ocean’s rise and fall as recorded off the coast of New Jersey reflects global sea level changes.
"The continents and oceans are continually shifting," Miller said. "We need to understand how they have changed in the past to anticipate changes in the future."
When the two-month-long New Jersey project finishes in late July, the ship, with a new team of scientists, will head to the Arctic Ocean to study water currents. After that, another group will sail to the waters off Brazil to study climatic cycles.
"Seventy per cent of the world is covered with water," staff scientist Peter Blum of Schaffhausen, Switzerland, said. "You don’t understand the Earth without understanding the ocean."
Source : The Malay Mail, July 23 1993
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