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 Published by the American Geological Institute
Newsmagazine of the Earth Sciences

 July 2000

Marine Geology

Donn S. Gorsline

As it does most of the geosciences these days, the question fueling much marine geology research is: How does it contribute to national needs? This trend harks back to the early days of continental surveys meant to evaluate the resources of a nation expanding westward.

Take for example the work of the U.S. Geological Survey on the U.S. coastal zone (Geotimes, June 2000). This work includes high resolution acoustic mapping of the sea floor that produces an "aerial photo" resolution of the morphology of the continental shelf and slope that can be reproduced at any desired perspective. The combination of these acoustic scans with analysis of the substrate based on acoustic signatures provides maps that can be used for a variety of applications. The utilization of sophisticated analytical and surveying equipment pervades the science of marine geology.

A major thrust is in the areas of paleoclimate and paleoceanographic studies that are increasing our understanding of the variety of climatic conditions that have occurred on Earth from the Precambrian to the present. Very briefly we can note two examples. (1) The "snowball" Earth theory (Science, v. 281, p. 1342-1346) which postulates that at times in the late pre-Cambrian and early Paleozoic the Earth atmosphere experienced major oscillations in carbon dioxide content resulting in an ice and snow-covered planet that returned to more normal conditions after volcanic action rebuilt the carbon dioxide content of the atmosphere. (2)  Under more "normal" climatic variations, driven in part by Milankovitch cycles, alternation of "ice house" conditions when glacial climates are present, equator-pole thermal gradients are steeper and ocean and atmosphere circulations are stronger, and "green house" conditions when the thermal gradient from equator to pole is less pronounced and ocean/atmosphere circulate less forcefully over a range of cyclicities produce different sedimentological signatures.

Unraveling these past conditions and variations requires the use of many chemical methods, detailed stratigraphic studies on the centimeter scale, comparisons of records in deep ocean cores from the Ocean Drilling Program, piston cores, ice cores from the ice caps, and cores from lakes and anoxic margin basins. A striking product of the study of Holocene-Late Pleistocene records is seeing how rapidly such changes can occur. The shift of climatic conditions into the Younger Dryas at around 11,000-11,500 years before the present probably occurred within a few decades, well within the life span of a Cro-Magnon (Geotimes, April 1999 and 1999 annual meeting of the American Association for the Advancement of Science).

These examples indicate the direction of the science: accumulating detailed records and maps of higher resolution from which we can distill a general theory explaining the rates and sequences of climate and ocean changes over most of Earth’s history.

Jobs in the next decade

Anecdotal evidence suggests that the number of students interested in environmental applications of geology will continue to increase. Professional training will need to be interdisciplinary, and the number of professional positions in marine science will be limited in an era that has moved away from labor intensive operations.

Over the next few years, in fact, the academic arena may well be the primary employment area for all earth science graduates with advanced degrees. The 1960s were years in which many jobs were available in government, industry and academia as those institutions expanded. This generation forms a major cohort in all employment fields and is now entering the retirement zone. Even allowing for some contraction, replacements will be sought. Universities will be the principal employers of marine geologists and other earth scientists. Note that advanced degrees are a must and, for most professional positions in all of the career areas, doctoral degrees will increasingly be the norm.

Another aspect of student recruitment is the increasing number of women in graduate schools, the number of women approaching parity with men in universities, and the increasing number of foreign students. We still need to work on recruiting minorities in the earth sciences, and on reversing what appears to be a trend of declining numbers of domestic students.

Marine geology graduates should be prepared to cover a broad range of fields. They should anticipate using their marine science training as a background for stratigraphic and sequence analysis in industry and environmental geology, in working with federal agencies to study the coastal zone, or in teaching general education courses in oceanography, geochemistry, stratigraphy and other fundamental areas. Research positions depending on federal funds are not likely to be promising pathways.

Gorsline is professor emeritus of earth sciences at the University of Southern California.

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