Cover image:
View from south to north of the Sierra Pinta Permian granitoid pluton, NW Sonora, Mexico. These calc-alkaline granitoid rocks of Permian age are associated with the early stages of subduction and the establishment of the Cordilleran continental arc of southwestern North America. Note that the foothills are unconformably covered by sandy deposits, which have been transported mainly by wind action, forming and shaping sand dunes. Photo: Harim E. Arvizu.