In a region defined by its magnificent geology, the formation of the Colorado Plateau and subsequent carving of the Grand Canyon have posed a longstanding problem for geoscientists. Typically when a region rises so dramatically in elevation, major deformations like mountains dominate the landscape. Instead, the topography of the 130,000 square-mile region is mainly flat, taking its shape from the slow forces of wind and water. In their research, which was published by the journal Nature on Wednesday, the team describes how they found a cold, dense area 120 miles beneath the Grand Canyon that was sinking deeper into the Earth. They say that the region chunked off pieces of the Earth's crust above it as it sank, and allowed another, much more buoyant layer to rise up and fill the chunked off space.