Each year as I review the highlights and accomplishments of the past 12 months for this introduction, I am reaffirmed in the basic commitment of the U.S. Geological Survey to provide "Earth Science in the Public Service." We are both proud of that motto and mindful of the vigilance and cooperation necessary to produce quality earth science that serves the public need and the public good.

It is easy sometimes for us as scientists to get wrapped up in our research and investigations and to forget that we are public servants as well as scientists. We must be ready with our science and with our time to meet the needs of legislators, policymakers, and the public for earth science information. Through this Yearbook, we have an opportunity to present our science as a public service and to fulfill our responsibility as public servants.

Perhaps the most telling theme of the pages in this volume is that of cooperation. Only by working together across lines of scientific disciplines and across lines of governmental responsibility can we achieve the level of excellence needed to provide earth science for the common good.

Through our extensive cooperative efforts with more than 1,000 other agencies and organizations we achieved some impressive results during the year. At the Federal level, we completed a four-year cooperative project between our bureau and the U.S. Bureau of the Census to help them prepare enumerator maps for the 1990 Decennial Census, and, in the process, we completed a computerized data base of our 1:100,000-scale map series far ahead of scheduled expectations.

Our cooperative effort to provide the basic hydrologic information for Connecticut's ground-water protection program, described in one of the lead essays, is just one example of how the Survey's broadscale national earth-science programs also serve State and local needs.

The USGS also has a vital program of international cooperation. The essay that describes our efforts with Canada to understand the geology beneath the Great Lakes

is an excellent example of how effectively science can reach across international borders. For nearly half a century now, the USGS has provided technical assistance in foreign countries and has conducted training in geology, hydrology, and cartography for visiting scientists from around the world. In the coming years, our international view will become more intense as the United States hosts the 28th International Geological Congress in Washington, D.C., in July 1989, which will bring the most prestigious earth scientists from more than 100 nations to the United States. We are also looking forward to several new initiatives getting underway to provide scientific expertise and assistance to other nations in dealing with natural hazards and their effects on a worldwide scale.

Exciting new applications of geographic information systems have afforded us an opportunity to conduct cooperative science that crosses discipline and organizational lines. Our geographic information. systems laboratory has become an exciting arena where scientists from every field of the geosciences have access to an extensive array of earth-science data in computergenerated format for analyzing a host of natural-resource and land-use problems. Here too, cooperation has been the hallmark of this effort's success. We have conducted demonstration projects with several State agencies and have a regular program for training other interested agencies in this new technology.

We continue to conduct research that is on the cutting edge of science seismic imaging that is revealing the structure of the deep crust of the Earth, advanced cartographic systems that are producing modern maps of incredible accuracy more rapidly than ever before, and complex computer modeling and sampling of organic compounds in water that is giving us a much better and much needed understanding of the fate and transport of these constituents in water systems.

USGS research is also at the forefront of many issues of national concern assessing the Nation's strategic and critical