It has been suggested that the Colorado Plateau acts as a semi-independent microplate and one way of explaining the creation of the Rio Grande rift is by the simple rotation of the Colorado Plateau 1-1.5 degrees in a clockwise direction relative to the North American craton. Other explanations that have been offered are that the extension is driven by mantle forces, such as large-scale mantle upwelling or small-scale mantle convection at the edge of the stable craton; collapse of over-thickened continental crust; initiation of transform faulting along the western margin of the North American plate; or detachment of a fragment of the Farallon plate beneath the Rio Grande region that enhanced asthenospheric upwelling in the slab window.