The Tibetan Plateau, the world's largest, highest and flattest plateau, has a much greater initial coverage area than originally believed, according to new research.

Writing in the journal Earth and Planetary Science Letters, an international team of researchers details the geological history of the so-called "Roof of the World."

"We've determined the elevation history of the southeast margin of the Tibetan Plateau," said study co-author Gregory Hoke, an assistant professor of Earth sciences at Syracuse University.

Hoke said that about 40 million years ago, during the Eocene epoch, the southern part of the Tibetan plateau extended by about 600 more miles to the east than previously documented.

"This discovery upends a popular model for plateau formation," Hoke said.

Six hundred miles is a great distance, but it pales in comparison to the size of the plateau itself, which stretches across more than 970,000 square miles in Asia - about four times the size of France - and reaches a height of more than 15,000 feet in some locations.

Rich mineral deposits infused in the plateau by glaciation, and the region's topography have made it of geological interest to scientists.

"The tectonic and topographic evolution of the southeast margin has been the subject of considerable controversy," Hoke said. "Our study provides the first quantitative estimate of the past elevation of the eastern portions of the plateau."

The established model for the Tibetan Plateau's formation is based on the theory that hot rock material flowed form high- to low-pressure zones helped elevate parts of the plateau about 20 million years ago.

But Hoke and his colleagues offer another idea that challenges the currently accepted model. Hoke's data suggests that the Tibetan Plateau has been at its present elevation since the Eocene epoch, and that surface uplift caused by low crustal flow the plateau's southern ridge has been historically small. He suggests that at some point a major fault line slip must have occurred that would have reshaped the region.

"Our data provides the first direct documentation of the magnitude and geographic extent of elevation change on the southeast margin of the Tibetan Plateau, tens of millions years ago," Hoke said. "Constraining the age, spatial extent, and magnitude of ancient topography has a profound effect on how we understand the construction of mountain ranges and high plateaus, such as those in Tibet and the Altiplano region in Bolivia."