Abstract Today, elementary physics students take for granted such quantities as “big G,” the universal gravitational constant. In fact, in the late 1700s the value of this quantity was unknown, and the quest to determine it led to some of the earliest geophysical instrumentation. Just after the Revolutionary War in the United States, Henry Cavendish developed the first system to measure the universal gravitational constant, the familiar “big G.” Unfortunately, for geologists (at this time still mostly “gentlemen scientists”), this apparatus produced data which were difficult to interpret geologically, and it was far too large and cumbersome for field use. The geologic limitation was that the system measured only the horizontal derivative of a horizontal component of the gravity field, a quantity which by itself is difficult to interpret. Thus no applications of this elegant yet laboratory-bound instrument emerged. Almost a full century later, the great Hungarian physicist Baron von Eötvös designed an instrument which would revolutionize the petroleum industry. As is often the case in revolutionizing technology, Eötvös used “new” fiber technology to significantly reduce the instrument's size and thereby increase portability. Eötvös also added a significant new feature. His master stroke was a design which suspended the weights on the torsion balance at different elevations. This modification made it possible to measure both the horizontal derivative of the horizontal field and the derivative of the vertical field (Figure 1). The vertical derivative was significantly easier to interpret geologically.

Abstract The history and scientific significance of three Late Jurassic pterosaur specimens housed in different Hungarian palaeontological collections are described. One of these is the holotype of Pterodactylus micronyx Meyer 1856 that was thought to be lost, but with its rediscovery in the 1980s the ‘Pester Exemplar’ becomes the name-bearing type again. The second specimen is an articulated, partially three-dimensional skeleton of a Rhamphorhynchus muensteri ; and the third is an articulated right hindlimb of a Pterodactylus sp. – both donated by Andor Semsey to the Hungarian Geological Institute. The anatomical revision of the holotype of P. micronyx indicated the osteological immaturity of the specimen; however, there is insufficient data on this taxon to assess its taxonomic validity.

Abstract Scientists have long been trained to build on the successes or failures of their predecessors, their teachers, and their fellows largely through scientific associations and their publications. Such societies range from small, local ones to huge organizations with membership drawn from over 100 countries. The oldest and most prestigious for geophysicists is the Royal Society, given both its name and charter by Britain’s King Charles II back in 1660. The Royal Astronomical Society, chartered in 1820, has also had a marked interest in geophysical matters, even to the extent of publishing a Geophysical Journal , because the earth is very much a part of the planetary system. Within the United States, the prestigious National Academy of Sciences (NAS) was started as an ally of government at the initiative of President Abraham Lincoln who asked the scientific community in 1863 for technical assistance with the war effort. Geophysical societies per se did not appear until the early 1900s. As a result of the great San Francisco earthquake, the Seismological Society of America (SSA) was formed in 1906. The International Union of Geodesy and Geophysics (IUGG) came into being in 1911, while its U.S. interface, the American Geophysical Union (AGU), was finally organized in 1919. The field of exploration geophysics lagged even further, with the Society of Exploration Geophysicists not being incorporated until 1930.

Abstract The gravity method was the first geophysical technique to be used in oil and gas exploration. Despite being eclipsed by seismology, it has continued to be an important and sometimes crucial constraint in a number of exploration areas. In oil exploration the gravity method is particularly applicable in salt provinces, overthrust and foothills belts, underexplored basins, and targets of interest that underlie high-velocity zones. The gravity method is used frequently in mining applications to map subsurface geology and to directly calculate ore reserves for some massive sulfide orebodies. There is also a modest increase in the use of gravity techniques in specialized investigations for shallow targets. Gravimeters have undergone continuous improvement during the past 25 years, particularly in their ability to function in a dynamic environment. This and the advent of global positioning systems (GPS) have led to a marked improvement in the quality of marine gravity and have transformed airborne gravity from a regional technique to a prospect-level exploration tool that is particularly applicable in remote areas or transition zones that are otherwise inaccessible. Recently, moving-platform gravity gradiometers have become available and promise to play an important role in future exploration. Data reduction, filtering, and visualization, together with low-cost, powerful personal computers and color graphics, have transformed the interpretation of gravity data. The state of the art is illustrated with three case histories: 3D modeling of gravity data to map aquifers in the Albuquerque Basin, the use of marine gravity gradiometry combined with 3D seismic data to map salt keels in the Gulf of Mexico, and the use of airborne gravity gradiometry in exploration for kimberlites in Canada.