Above: The Glomar Challenger was the first research vessel specifically designed in the late 1960s for the purpose of drilling into and taking core samples from the deep ocean floor. Below: The JOIDES Resolution is the deep-sea drilling ship of the 1990s (JOIDES= Joint Oceanographic Institutions for Deep Earth Sampling). This ship, which carries more than 9,000 m of drill pipe, is capable of more precise positioning and deeper drilling than the Glomar Challenger. (Photographs courtesy of Ocean Drilling Program, Texas A & M University.)

"Developing the theory"