Book excerpt: Deformation of the Earth’s crust happens at a multitude of scales, ranging from submicroscopic to planetary. Tectonics explores structures and processes from regional to global, differentiating itself from the material covered in most structural geology textbooks. Moores and Twiss emphasize basic principles and methodologies of tectonics, embracing the time-honored perspective of using present processes to understand the past. Comprehensive in scope and detail, coverage includes the effects of plate motions and reconstructions and the resultant structures associated with active rift, transform, and subduction boundaries as well as triple junctions and collision zones; deformations of both the ocean basins and the continents; and orogenic belts. Moores and Twiss present tectonics as an open-ended field of study in which assumptions can be challenged and interpretations changed. The authors emphasize the use of models as a means of understanding observations and putting them in context to maintain a distinction between what we know from observing the Earth and what we infer from interpretation.