Lithosphere today...

摘要

Large-scale uplift, erosion and volcanic activity are standard features of mountain belts that are subject to the horizontal tectonic forces associated with plate movements. But somehow, in the past 70 million years, possibly quite recently, the virtually undeformed Colorado plateau of the southwestern United States was uplifted about 2 kilometres, intruded by diverse magmas, and eroded and deeply incised, creating a dramatic topography that includes the 1.8-km-deep Grand Canyon. This enigmatic history has perplexed geologists for more than a century.