OCE-9503561 This project will conduct an off-axis geophysical survey out to about 28 million year old crust on the eastern flank of the Mid- Atlantic Ridge near 26 degrees north. The survey will cover crust that is conjugate to a similar, detailed survey that already has been completed on the west flank. Together, the conjugate data sets will provide a uniquely detailed and long-term record of ocean crustal structure that will provide fundamental new insights into the origin, structure, and evolution of slowly spreading ocean crust.