Clues Suggest How Grand Canyon Formed New data explains rising of huge Colorado Plateau By Matt Cantor, Newser User Posted Apr 30, 2011 3:02 PM CDT 68 comments Comments Geologists gain an insight into the canyon's formation. (Shutterstock) (Newser) – We know the Grand Canyon was formed when the vast Colorado plateau rose from the ground, then eroded. But scientists have long been stumped as to why the 130,000-square-mile region pushed more than a mile upward. Now, a team of researchers may have found the answer, and it lies in a strangely cold layer underneath the canyon. That “anomaly” in the lithosphere—a layer that includes the earth’s crust and upper mantle—may have been caused by molten matter rising from below, OurAmazingPlanet reports. Cooling, that material weighed down the upper mantle, causing peeling and what scientists call a “mantle drip.” That, in turn, opened space for the hotter lower layer, called the asthenosphere, to fill. The expansion of the material from the asthenosphere finally pushed the plateau upward, the scientists suggest. The new data also points to the Grand Canyon’s age, lending weight to a theory “that it formed in the last 6 million or 7 million years,” a researcher says.