Geochemical techniques played a major role in exploration of the Tonkin Springs district and ultimately led to discovery of economically significant bodies of gold mineralization. Using some of the information obtained during the exploration program, it is possible to review the geochemical environment, secondary dispersion processes and survey techniques used successfully in this part of Nevada.

The Tonkin Springs district is located in west-central Eureka County, Nevada, within the Simpson Park Range approximately 65 km northwest of the town of Eureka (Figure 7.1). Topography is typical of the Basin and Range structural province being characterized by long narrow valleys and north easterly trending mountain ranges with elevations varying between 1,700 and 3,100 m. Precipitation is in the order of 400 mm per year, the major portion of which occurs in the higher elevations during winter and spring. Soils are light brown to brown desert soils of residual origin in locations above the gravel-filled valleys and pediments. Vegetation consists of sagebrush and sparse grass in the valleys with juniper, pinyon and mountain mahogany in the higher country.

Electrical well logging was introduced to the oil industry over a half century ago. The first log was recorded on September 5, 1927, in a well in the small oil field of Pechelbronn, in Alsace, a province of northeastern France. This log, a single graph of the electrical resistivity of the rock formations cut by the borehole, was recorded by the “station” method. The downhole tool (called a sonde) was stopped at periodic intervals in the borehole, measurementsw ere made, and the calculated resistivity was hand-plotted on a graph. This procedure was repeated from station to station until the entire log was recorded.<...>

Ideas that karst can develop at depth without direct genetic relationship to the surface have a long history, but remained on the periphery of karstological thinking, not influencing the traditional paradigm of karst until the last 25 years. More attention to hypogene karst since 1990, and particularly the dramatic burst of studies in this field during the last decade, has changed our notion of hypogene karst from a curiosity to one of the fundamental categories of karst, at least of compatible importance with more familiar epigene karst. <...>

Cave geology, as treated in this book, concerns not only the geology and origin of caves, but also related aspects such as hydrology, geochemistry, and microbiology. All cave sciences are combined in the field otspeteolag)'. More than any other science, speleology is closely tied to exploration and adventure. Anyone can participate in it.