Abstract The Pliocene fossiliferous succession of the Volterra hill, a prominent place in Tuscany, Italy and, since the Renaissance, the site of important archaeological finds of the ancient Etruscan civilization, has formed the object of enquiry over six centuries of research on the inner nature of the Earth system. The works of Restoro d'Arezzo, Leonardo da Vinci, Nicolaus Steno, Giovanni Targioni, Nicolas Desmarest, Giambattista Brocchi, Alexandre Brongniart and Charles Lyell testify to the early recognition through fieldwork that those strata with seashells had formed at the bottom of the sea. This interpretation served different approaches to knowledge. Restoro, Leonardo and Steno, spanning nearly four centuries in the history of science (1282–1669), including the ‘Copernican Revolution’ and the start of the Modern Age, relied also on textual sources and trusted a speculative model of the Earth's interior, so that at Volterra they focused on vertical movements of the earth–water system. The authors of the eighteenth and nineteenth centuries abandoned pre-built young-Earth models and emphasized the geography of ancient Tuscany. Brocchi, Brongniart and Lyell promoted the taxonomic use of seashells to correlate rocks across Europe. This place deserves higher standards of valorization to promote understanding of the history and sociology of ideas.

Abstract The goal of this book is to provide information about the principles, understanding, and applicability of the gravity exploration method. This book is intended to be suitable for classroom instruction and as a reference for anyone engaged in geophysical exploration, including those whose specialties might be in another discipline but who would benefit from an understanding of how gravity exploration can help them solve exploration problems. For many decades, the 1971 SEG book by L. L. Nettleton (Geophysical Monograph Series No. 1, Elementary Gravity and Magnetics for Geologists and Seismologists ) has helped to fill this need, but it is limited in scope (as its title implies) and is, of course, out of date, especially with respect to modern exploration technology. This little book has been a best seller, however, and it resides in the libraries of thousands of geologists and geophysicists. It contains several classical and practical examples of how the gravity method can be applied, and we have borrowed liberally from these where they retain their long-held value. In 1995, Richard J. Blakely published Potential Theory in Gravity and Magnetic Applications . This book covers in depth much of which the Nettleton monograph lacks: the principles of potential theory and the mathematical basis for the forward and inverse techniques of interpretation. Our book is intended to fill a need that is oriented more toward exploration than the Nettleton monograph or the Blakely book, with more information about the underlying principles and technology than the former and clearer orientation toward the explorationist's