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 accessible, hidden beneath waters (1) ______
averaging over 3, 600 meters deep. Totally without light and
subjected intense pressures hundreds of times greater than at the Earth’s (2) ______
surface, the deep-ocean bottom is a hostile environment to humans,
in some ways as forbidding and remote as the void of out space. (3) ______
Therefore researchers have been taking samples of deep-ocean (4) ______
rocks and sediments for over a century, the first detailed global
investigation of the ocean bottom did actually start until 1968, with (5) ______
the beginning of the National Science Foundation’s Deep Sea Drilling
Project (DSDP). Used techniques first developed for the offshore (6) ______
oil and gas industry, the DSDP’ s drill ship, the Glomar Challenger,
was able to maintain a steady position on the ocean’s surface and
drill very deep waters, extracting samples of sediments and rock (7) ______
from the ocean floor.
The Glomar Challenger’s core samples have allowed geologists to
reconstruct that the planet looked like hundreds of millions of years ago (8) ______
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 with the (9) ______
theories of plate construction and continental drift that explain many of
the geological processes that shape on the Earth. (10) ______