This report responds to a request by the U.S. Geological Survey (USGS) that the National Research Council (NRC) review its concept of The National Map. The National Map is envisioned by USGS as a database providing “public domain core geographic data about the United States and its territories that other agencies can extend, enhance, and reference as they concentrate on maintaining other data that are unique to their needs” (USGS, 2001).

On a recent afternoon spent in London’s Natural History Museum (NHM), I noticed that a life-size animatronic Velociraptor had finally sprouted feathers. They might have been a touch sparse compared to the plumage of counterparts in museums elsewhere, but it was encouraging to see them there. A few years earlier, the Tyrannosaurs: Meet the Family exhibition at the Australian Museum in Sydney had featured not only wonderful feathered fossils from China, but also models of shaggy carnivores that could have been swiped from Jim Henson’s workshop yet were still creepy enough to strike fear into the hearts of gobsmacked kids. <...>

This book was prepared under the auspices of the Technical Publications Committee (TPC) of the International Association of Drilling Contractors (IADC). The TPC, as a group, contributed to this book by first by approving its concept, and then by reviewing and authorizing the basic outline for the book. My thanks to the past and current officers of the committee including Dr. Leon Robinson (deceased) and Dr. Fred Growcock, Chair; Nace Peard and Mark Morgan, Vice-chairs; and Dr. Arash Haghshenas, Group Leader for the Planning, Practices, and Guidelines group, each of whom provided encouragement and advice on the book's construction and content.

Well logging lies at the intersection of applied geophysics, petroleum and geotechnical engineering. It has its roots in the tentative electrical measurements in well bores which were made by the Schlumberger brothers some 80 years ago in the earliest days of systematic petroleum exploration. Today, a variety of specialized instruments is used to obtain measurements from the borehole during, as well as after, the drilling process. This readable and authoritative treatment of the physics of these measurements dispels the "black magic" of well log interpretation by relating them, including those obtained by the latest generation of tools, to rock physics. It offers a thorough exposé of the physical basis of borehole geophysical measurements, as well as an introduction to practical petrophysics -- extracting desired properties from well log measurements.