Our purpose in writing this textbook, now updated to a third-edition view of the world, is to communicate the physical and geometric elegance of geologic structures within the Earth’s crust, and to describe the ways in which they reflect the nature and origin of crustal deformation through time (Figure 1.1). Geologic structures provide part of the basis for recognizing and reconstructing the profound changes that have marked the physical evolution of the Earth’s outermost layers, as observed from the scale of the plates down to the microscopic. Understanding the nature and extensiveness of geologic structures of deformational origin in the Earth’s crust has both scientific and practical benefit. But there is a philosophical value as well. <...>

Many textbooks describe information and theories about the Earth without training students to utilize real data to answer basic geological questions. This volume – a combination of text and lab book – presents an entirely different approach to structural geology. Designed for undergraduate laboratory classes, it is dedicated to helping students solve many of the geometrical problems that arise from field observations.

The arrangement of chapters in the book follows the same outline as previous editions, with no major organizational changes. One thing that may be noticeable is that much of the discussion of the historical basis of concepts and ideas has been moved to essays. This permits students who are interested in the historical development of structural geology to explore further, but it does not interrupt the overall flow of chapters.

The classification of minerals has changed throughout the ages, the criterion of classification following the development of the mineralogical science. In ancient times, the classification of minerals was mainly based on their practical purposes. According to Theophrastus (372-287 B.C.), and Plinius (77 A.D.), minerals were classified as gemstones, ores, pigments, etc. In the Middle Ages, Geber (Jabir Ibn Hayyi'm, 721-c.803), proposed a classification based on the external characteristics and some physical properties of minerals such as hardness, fusibility, malleability and fracture; this physical classification was developed later by  Avicenna (Ibn Simi, 980-1037), and Agricola (1546). With Werner (1774) the physical classification attained its maturity and was generally adopted at the end of the XVIII century. <...>