Natural Aggregate -- Geophysical Opportunities

During the early part of the 20th Century, the increased demand for surfaced roads prompted a<br>number of reports in the geologic literature on using aggregate for highway construction. Since that<br>time many other excellent reports concerning research, development, testing, and evaluation of natural<br>aggregate - crushed stone, sand, and gravel - have been written. However, most professional geologists<br>and geophysicists, even those who work in the mineral-resource field, commonly ignore natural<br>aggregate in favor of other seemingly more glamorous aspects of geology.<br>Today, at the beginning of the 21st Century, we recognize the indisputable need for a continuing<br>and uninterrupted supply of high quality aggregate. The United States annually produces over 2.5<br>billion tons of aggregate, which represents approximately 9 tons per person per year. During the next<br>decade, the restoration and rehabilitation of an aging infrastructure will require enormous amounts of<br>aggregate, much of which will need to meet strict specifications for new high-performance construction<br>materials. In addition, stringent environmental laws, land-use conflicts, zoning restrictions, and the "Not<br>in my back yard" syndrome make it increasingly difficult, time-consuming, and costly to obtain permits<br>for extraction of aggregate.<br>Geophysicists have the opportunity to provide critical information concerning the identification,<br>characterization, and extraction of suitable aggregate, and concerning protection of the environment<br>from adverse impacts of aggregate extraction. Geophysical surveys of aggregate deposits also provide<br>opportunities for conducting traditional research on geophysical methods. Research is needed on<br>techniques to efficiently acquire and process ground-based geophysical data, airborne geophysical data,<br>and remotely sensed data. Such data are needed to detect and delineate potential sources of crushed<br>stone and deposits of sand and gravel. Better techniques are also needed to determine deposit thickness,<br>characterize variations within a deposit, characterize physical properties of aggregate resources,<br>characterize mine sites, and characterize areas of potential environmental impacts.<br>It is time to shift paradigms, to implement new ideas and methods, to get involved in aggregate<br>research. In doing so, the inquisitive geophysicist will soon recognize numerous challenging<br>opportunities that make natural aggregate a subject as fascinating and rewarding as any other aspect of<br>geophysics.