Preface: Structural balancing at the start of the 21st century: 100 years since Chamberlin

The seminal paper by Rollin Chamberlin (1910) is regularly cited as the first paper on the topic of what is today broadly known as balanced cross sections. This special issue grew out of a theme session commemorating the 100th anniversary of the paper's original publication, held at the 2010 Geological Society of America Annual Meeting in Denver, Colorado. Chamberlin's paper presents a quantitative method and field example in which the observable geometry of part of a structure is used to predict an unseen part. In this sense the paper provides a conceptual background for the current use of models to predict structural geometries. That Chamberlin's prediction of the Appalachian lower detachment, based on methods still in use, was wrong in light of later data, suggests the need for revisiting the topic. The purpose of this collection of papers is to provide a critical assessment of predictive balancing and restoration techniques from an early 21st century standpoint. In this introduction we present a brief overview of the development of structural balance theory, and the development and implications of structural balance software on theory and application.