<P> The Laramide orogeny affected all of western North America by helping to build the American cordillera . The Kaibab Uplift, Monument Upwarp, the Uinta Mountains, San Rafael Swell, and the Rocky Mountains were uplifted, at least in part, by the Laramide orogeny . This major mountain - building event started near the end of the Mesozoic, around 75 million years ago, and continued into the Eocene period of the Cenozoic . It was caused by subduction off the western coast of North America . Major faults that trend north--south and cross the canyon area were reactivated by this uplift . Many of these faults are Precambrian in age and are still active today . Streams draining the Rocky Mountains in early Miocene time terminated in landlocked basins in Utah, Arizona and Nevada but there is no evidence for a major river . </P> <P> Around 18 million years ago, tensional forces started to thin and drop the region to the west, creating the Basin and Range Province . Basins (grabens) dropped down and mountain ranges (horsts) rose up between old and new north--south--trending faults . However, for reasons poorly understood, the beds of the Colorado Plateaus remained mostly horizontal through both events even as they were uplifted about 2 miles (3.2 km) in two pulses . The extreme western part of the canyon ends at one of the Basin and Range faults, the Grand Wash, which also marks the boundary between the two provinces . </P> <P> Uplift from the Laramide orogeny and the creation of the Basin and Range province worked together to steepen the gradient of streams flowing west on the Colorado Plateau . These streams cut deep, eastward - growing, channels into the western edge of the Colorado Plateau and deposited their sediment in the widening Basin and Range region . </P> <P> According to a 2012 study, there is evidence that the western Grand Canyon could be as old as 70 million years . </P>

What most likely created the sedimentary rock in the grand canyon