READING COMPREHENSION
Questions 1-9
The ocean bottom ------a region nearly 2.5 times greater than the total land area of the
Earth ---- is a vast frontier that even today is largely unexplored and uncharted. Until
about a century ago, the deep-ocean floor was completely inaccessible, hidden beneath
waters averaging over 3,600 meters deep. Totally without light and subjected to intense
pressures hundreds of times greater than at the Earth s surface, the deep-ocean bottom
is a hostile environment to humans, in some ways as forbidding and remote as the void
of outer space.
Although researchers have taken samples of deep-ocean rocks and sediments for
over a century, the first detailed global investigation of the ocean bottom did not
actually start until 1968, with the beginning of the National Science Foundation s Deep
Sea Drilling Project (DSDP).Using techniques first developed for the offshore oil and
gas industry, the DSDP s drill ship, theGlomar Challenger, was able to maintain a
steady position on the ocean s surface and drill in very deep waters, extracting samples
of sediments and rock from the ocean floor.
The Glomar Challenger completed 96 voyages in a 15-year research program that
ended in November 1983. During this time, the vessel logged 600,000 kilometers and
took almost 20,000 core samples of seabed sediments and rocks at 624 drilling sites
around the world. The Glomar Challenger s core samples have allowed geologists
to reconstruct what the planet looked like hundred of millions of years ago and to
calculate what it will probably look like millions of years in the future. Today, largely
on the strength of evidence gathered during the Glomar Challenger s voyages, nearly
all earth scientists agree on the theories of plate tectonics and continental drift that
explain many of the geological processes that shape
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