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FROM THE EDITOR | November 1998 |
Geologic changes are typically measured in millimeters or centimeters.
Yet once in awhile, we experience a change so profound it renders trusty
landmarks useless. A number of these profound moments have occurred since
the beginning of our science. Although these paradigm-shifting theories
are part of the history books, today’s geoscientists know that our era
has witnessed
equally exciting breakthroughs.
Sam Adams’ “Comment” calls for unity in the geosciences — not to tear down walls between disciplines, but to work symbiotically by sharing common ideas and resources. This theme will also be the focus of an AGI symposium on Nov. 14, at the National Academy of Sciences in Washington, D.C.
Photographs and images of Earth from space have given recent geoscientists a truer sense of where we are in our solar system. Authors James Reilly, William Muehlberger, Patricia Dickerson, Harrison “Jack” Schmitt, and John Young have helped direct NASA’s use of photographs and remote-sensing images of Earth. Their account and their breathtaking photographs make us realize how much we’ve learned by “stepping back” with the astronauts and looking.
One cannot talk about revolutions in science without discussing plate tectonics. On a par with the theories of evolution and relativity, plate tectonics has provided a unifying context for the geosciences. As author William R. Dickinson writes, “Plate tectonics gave geoscience its own scientific revolution, and our business has never been the same since.”
With lithospheric plates established as mobile and interacting, the mantle and core were recognized as dynamic regions driving the system. Advances in high-pressure mineralogical research and seismic characterization helped push an understanding of the composition and structure of the core and mantle to new heights (or new lows?). Thorne Lay and Quentin Williams guide us through this fascinating field of research.
Thanks to new developments in geochronology, we are able to date Earth far more accurately now than 50 years ago. Born with the discovery of radioactive elements at the end of the last century, the field of geochronology has particularly benefited from advances in instrumentation in recent decades. Samuel Bowring describes how new theories of radioactive decay have led to a critical, expanded understanding of Earth processes.
Since the days when basic principles of correlating and mapping stratigraphic units were displayed in William Smith’s cross sections, little had changed in stratigraphy. But when sequence stratigraphy first “went public” in the mid-1970s, it hit the petroleum industry like a tsunami sweeping over a broad coastal plain. Gerald Baum, with Peter Vail, shows us a revolution in the applied geosciences — one that changed the way geologists and geophysicists looked at their cross sections and seismic lines and got them talking to each other. Now that’s truly revolutionary.
In her article, “Imaging Earth,” Sally Zinke explains how advances in engineering techniques and computer technology have profoundly affected seismic imaging. Pushed by the petroleum industry and now spurred on by environmental concerns, seismic imagery is reaching new levels of detail. From analog systems and data, common when AGI was just a dream, to the multiprocessed 3-D and 4-D digital data of today, seismic images are helping us refine our image of Earth.
Guest columnist Catherine Skinner has the last word this month, asking “Where are we going?” Her answer focuses on integration. The varied disciplines of the geosciences must come together, and we must develop stronger connections with the other sciences. Only then can we fulfill our destiny of being good stewards of Earth. Happy 50th, AGI. Good reading.
Victor V. van Beuren
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