Articles in this special issue of Oceanography represent a compendium of research that spans the disciplinary and thematic breadth of the National Science Foundation’s Ridge 2000 Program, as well as its geographic focal points. The mid-ocean ridge (MOR) crest is where much of Earth’s volcanism is focused and where most submarine volcanic activity occurs. If we could look down from space at our planet with the ocean drained, the MOR’s topography and shape, along with its intervening fracture zones, would resemble the seams on a baseball, with the ocean basins dominating our planetary panorama. The volcanic seafloor is hidden beneath the green-blue waters of the world’s ocean, yet therein lie fundamental clues to how our planet works and has evolved over billions of years, something that was not clearly understood 65 years ago—witness the following quote from H.H. Hess (1962) in his essay on “geopoetry” and commentary on J.H.F. Umbgrove’s (1947) comprehensive summary of Earth and ocean history:

The birth of the oceans is a matter of conjecture, the subsequent history is obscure, and the present structure is just beginning to be understood. Fascinating speculation on these subjects has been plentiful, but not much of it predating the last decade [the 1950s] holds water.

Fornari, D.J., S.E. Beaulieu, J.F. Holden, L.S. Mullineaux, and M. Tolstoy. 2012. Introduction to the special issue: From RIDGE to Ridge 2000. Oceanography 25(1):12–17, https://doi.org/10.5670/oceanog.2012.01.

Carbotte, S.M., R. Arko, D.N. Chayes, W. Haxby, K. Lehnert, S. O’Hara, W.B.F. Ryan, R.A. Weissel, T. Shipley, L. Gahagan, and others. 2004. New integrated data management system for Ridge2000 and MARGINS research. Eos, Transactions American Geophysical Union 85(51):553, https://doi.org/10.1029/2004EO510002.
1. Hess, H.H. 1962. History of ocean basins. Pp. 599–620 in Petrologic Studies: A Volume in Honor of A.F. Buddington. A.E.J. Engel, H.L. James, and B.F. Leonard, eds, Geological Society of America, New York.
2. Ocean Studies Board. 1988. The Mid-Oceanic Ridge: A Dynamic Global System. Proceedings of a Workshop. National Academy Press, Washington, D.C.
3. Rubin, K.S., and D.J. Fornari. 2011. Multidisciplinary collaborations in mid-ocean ridge research. Eos, Transactions American Geophysical Union 92:141–142, https://doi.org/10.1029/2011EO170002.
4. Ryan, W.B.F., S.M. Carbotte, J. Coplan, S. O’Hara, A. Melkonian, R. Arko, R.A. Weissel, V. Ferrini, A. Goodwillie, F. Nitsche, and others. 2009. Global multi-resolution topography (GMRT) synthesis data set. Geochemistry Geophysics Geosystems 10, Q03014, https://doi.org/10.1029/2008GC002332.
5. Umbgrove, J.H.F. 1947. The Pulse of the Earth. Martinus Nijhoff, The Hague, 358 pp.

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