The Young Scientists

Jason Morgan, Geophysics
Our research cruise this summer from Panama to Acapulco and San Diego included myself, five under- graduates, and one graduate student. In addition, there were five Navy scientists and 25 merchant marine crew members. We were on a new 215-foot ship designed for general oceanographic research and were mainly concerned with measuring the ocean bottom. Two areas along the Central American coast were surveyed in detail. We also did some dredging and coring of the ocean floor. Dredging is scooping up sediment and rock fragments in a bucket at the end of a five-mile wire rope. For coring, a three-inch pipe with a thousand-pound weight on it is sunk into the ocean floor. Then it is pulled up, filled with mud. The samples are examined, and by the species of shells and the kind of rocks obtained, it is possible to tell the age of the sediment. Several of us will be occupied with analyzing the data from the cruise throughout most of the fall and winter.

In a typical day on board, you spend half of a watch, or four hours, monitoring the instruments, that is, writing down the time and the magnetic and bathymetric readings. The machines work around the clock. The magnetometer is towed 700 feet behind the ship. When the dredging and coring begin, everyone, including some of the crew, helps manipulate the heavy equipment. Coring takes three hours, dredging, six. Then there is preparation for data collection and the putting away of the results.

This was the largest summer oceanographic cruise Princeton has participated in, and student participation was high. There are some advantages to not being at an oceanographic institute, surprisingly enough. When you have a ship of your own, it’s necessary to keep it constantly in operation. So you end up going to sea more often than you might wish for your own research interests. And continuous cruising means the processing of enormous volumes of data. There is an advantage to having several months to sit back and think about the findings of a cruise. The other side of this is, of course, that there is no ship available should you like to go to some far-off place without making elaborate preparations long in advance.

My thesis on gravitational waves led me into geophysics. On a post-doctoral fellowship in geophysics I started to work on convection currents in the earth’s mantle. My particular part of that project was to work out a theoretical model compatible with observations on oceanic trenches. We were trying to estimate the size of the sinking mass on the basis of our information about convection currents in oceanic trenches. This is a subject to which I’ve returned on and off since then. Particularly I’ve been able to do more on this since the Geophysical Fluid Dynamics Laboratory moved to the Forrestal Campus a few years ago…