Innovations in engineering and adaptations of mining technologies over the last 50 years have enabled scientific ocean drilling to reveal much about the deep Earth that would have been impossible using any other methods. However, this so-called “deep” drilling has not penetrated more than the top few hundred meters into igneous basement in most holes, and even when applying multi-expedition approaches, it has only reached as far as two kilometers into in situ oceanic crust (Hole 504B in the eastern equatorial Pacific). Many challenges and questions remain, and new areas need to be pursued through continued drilling efforts. We still have not answered the fundamental Earth science question: Is the Mohorovičić Discontinuity a lithological transition, a geophysical boundary, a serpentinization front, or a combination of those?

Koppers, A.A.P. 2019. Future opportunities in scientific ocean drilling: Deep earth. Oceanography 32(1):193, https://doi.org/10.5670/oceanog.2019.143.

This is an open access article made available under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution, and reproduction in any medium or format as long as users cite the materials appropriately, provide a link to the Creative Commons license, and indicate the changes that were made to the original content. Images, animations, videos, or other third-party material used in articles are included in the Creative Commons license unless indicated otherwise in a credit line to the material. If the material is not included in the article’s Creative Commons license, users will need to obtain permission directly from the license holder to reproduce the material.