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
(10) 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, the Glomar 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.
(15) 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 hundreds of millions of years ago and to
(20) 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 the Earth.
The cores of sediment drilled by the Glomar Challenger have also yielded
(25) information critical to understanding the world's past climates. Deep-ocean sediments
provide a climatic record stretching back hundreds of millions of years, because they
are largely isolated from the mechanical erosion and the intense chemical and biological
activity that rapidly destroy much land-based evidence of past climates. This record has
already provided insights into the patterns and causes of past climatic change---
information that may be used