In the ten years that have passed since the publication of the first edition of this textbook exciting advances have taken place in every discipline of geophysics. Computer-based improvements in technology have led the way, allowing more sophistication in the acquisition and processing of geophysical data. Advances in mass spectrometry have made it possible to analyze minute samples of matter in exquisite detail and have contributed to an improved understanding of the origin of our planet and the evolution of the solar system. Space research has led to better

After a 20-year hiatus, we are pleased to bring you the 2nd Edition of Fundamentals of Groundwater. Like its predecessor, the book is written at an introductory level to facilitate learning and teaching, while maintaining appropriate rigor. Not surprisingly, much has changed with this edition in terms of its look and feel and importantly the content. Most obvious is the use of color in many figures throughout the book. As the book progressed, the dearth in high-quality colored figures and photographs in traditional journal articles became obvious. Fortunately, here in the United States, groundwater-related documents and reports of the U.S. Geological Survey represent a valuable treasure of high-quality graphical material.

The idea of this brief chapter is to introduce students to the concept of fossil occurrences and their use, through geological time. An approach that defines the geological time scale, a method of relating the timing and relationship between events that have occurred during Earth’s history. The Geologic time is divisible into four Eons, Hadean, Archean, Proterozoic, and Phanerozoic (Fig. 1.1). The Eons are further divided into Eras; the Phanerozoic is divided into Paleozoic, Mesozoic, and Cenozoic (Fig. 1.1). The Eras are based on major changes in fossils record (such as extinction and origination; the latter is the appearance of new forms). The Eras are further divided into smaller units called Periods, in which a single type of rock system is formed; these are further divided into Epochs like the Paleogene is divisible into Paleocene, Eocene, and Oligocene (Fig. 1.1). However, in spite of a long impressive fossil record, it is also interrupted by major and minor extinction events (Fig. 1.1; see also Hart 1996; Hallam and Wignall 1997; Koeberl and MacLeod 2002; Taylor 2009). The Phanerozoic record of marine invertebrates, in particular, is interrupted by numerous, geologically short-term intervals (generally <3 Ma) during which biotic diversity and abundance declined significantly (<40 % at the familial level and <63 % at the generic level) (Raup and Sepkoski 1986) (see Fig. 1.1). Extinctions (major and minor) do not fall within the preview of this book but have only been mentioned to allude to the interruptions within the fossil record. <...>

This is the third edition of our book Fundamentals of Ocean Acoustics, revised and supplemented, including much new material responding to the progress in the theory of sound propagation and scattering in the ocean over the last 10 years. New topics are devoted mainly to such questions as the intrathermoclinc lenses and their effect on sound fields in the ocean, weakly divergent bundles of rays, ocean acoustic tomography, coupled modes, invariants of an interference pattern in a range-dependent oceanic waveguide, sound scattering by random highly anisotropic volume inhomogeneities (fluctuations of the refractive index of the sea medium) with a fractal spectrum, fractal nature of low-frequency attenuation in the underwater sound channel, small-slope approximation in treating sound scattering from the rough sea surface (Voronovich's approach), sound scattering by an air bubble near the sea surface, collective bubble behaviour, etc. Both the direct and inverse problems arc considered. Some rccent experimental data arc also added. More than 60 new references are presented. Some new references and figures arc preceded by the letter A.The book is intended for experts in acoustics and oceanology, engineers, postgraduates, and students of universities and institutes of geophysical and hydrometeorological profiles. Thus, it can be used as a scientific monograph and textbook of advanced type. The authors arc grateful to T.l. Tsyplakova for her great help in preparing the manuscript.