Abstract The earliest detailed technical descriptions of British mining practices still in existence (which date from the late 17th and early 18th centuries) dedicate many paragraphs to the problems posed by the unwanted ingress of ground water into underground workings. Excessive water in working areas seriously hinders production. More importantly, sudden inrushes of ground water to underground workings are a significant mortal hazard. In view of the problems experienced with water ingress to workings, the main preoccupations of the early mining engineers were utterly practical, focusing on the efficient removal of water which could not be prevented from entering the workings (by simple bailing, by adit drainage or by pumping), and on efforts to minimize water ingress in the first place (by the use of tubbing in shafts and the use of rock barriers and dams in working areas). Occasionally, the mining engineers took time to reflect upon the origins of the water they encountered in their work. In their writings we find some of the earliest accurate conceptualizations of issues of ground water origin, driving heads, hydraulic gradients (including vertical upward gradients) and natural heterogeneities in water quality. So successful were these early mining engineers in their endeavours that they bequeathed most of the technological basis for the development of large-scale public-supply ground water abstractions, and much of the basis for the geotechnical control of ground water during construction projects, from about 1820 onwards. By the late 19th Century, mining engineers concerned with ground water management became gradually isolated once more within their own specialist domain, where they went on to develop a vernacular hydrogeology of their own, replete with its own key concepts and vocabulary. Nevertheless, occasional interchanges of experience between mining and the water industry have continued to enrich both sectors down to the present day.

Abstract Foraminifera were of little interest in North America until 1923, when Joseph Cushman demonstrated how these microfossils could be used for subsurface geologic correlation. Word spread quickly throughout the oil industry and their sudden demand for foram workers prompted academia to provide the necessary training. For the next 60 years, industrial exploration and development played a major role in maintaining a large presence of foraminiferologists in California. Although the major oil companies employed most of them, a few found careers in the major universities or with the US Geological Survey. In the 1980s, the Californian oil industry became less reliant on biostratigraphy and the numbers of micropaleontologists rapidly declined. The heyday of foraminiferal micropaleontology had passed and by the time offshore exploration was abandoned in the early 1990s, few foraminiferologists remained in the state. Today only a handful of seasoned foraminiferologists can be found working in California.

INTRODUCTION Chapter 3 treats electromagnetic (EM) profiling methods using small dipolaf sources. Profiling techniques are designed to detect changes in electrical conductivity laterally, along a traverse, in contrast to sounding techniques which are designed to determine variations in the conductivity of the earth with depth (see Spies and Frischknecht, this volume). The distinction between the two approaches is blurred when broadband or multispacing measurements are made at closely spaced stations. The source and receiver antennas are usually small loops which can be treated as magnetic dipoles, although, in practice, a grounded electric dipole could be used for either of the antennas. When dipolar sources are used in fixed positions, the methods have much in common with large source methods, so there is overlap between Chapter 3 and Chapter 4 by Parasnis (this volume). Most of the profiling techniques described operate in the frequency domain (which reflects their historical development), but many of the interpretation procedures are applicable in the time domain. A detailed discussion of time-domain methods is given in Nabighian and Macnae (this volume). The first and most common use of dipolaf source EM profiling methods is detection and characterization of highly conductive bodies, and most instrumentation and interpretative techniques have been developed for this application. In direct exploration for conductive mineral deposits the geologic model is generally assumed to consist of a highly conductive target such as a massive sulfide ore body in a much less conductive host rock covered by an overburden of intermediate conductivity. For this model to be realistic, however, varying the composition and thickness of the overburden may be necessary.