According to a report in Disocvery News, the evidence was found by Gaetano di Achille and a team of researchers at the University of Colorado in Boulder, US, in the form of an ancient shoreline ringing Shalbatana Vallis, a gash in Mars' surface just east of the massive volcanic province, Tharsis Rise
The northern hemisphere shows the "shields" presumably produced by eruptions from three huge volcanoes on an elevated region called the Tharsis rise
. There is a region west of Tharsis, however, that produces no radar echo at all.
According to CU-Boulder Geophysicist Shijie Zhong, the shell-like outer plate of the Red Planet might be moving, driven by a powerful single plume of hot material affecting an area of thickened crust called the Crustal Dichotomy, thus explaining the migration of volcanic activity in the Tharsis Rise region of Mars.
The second feature is the vast area of high elevation with numerous volcanoes near the equator covering a quarter of the Martian surface, known as the Tharsis Rise.
"This would explain the migration of volcanic activity in the Tharsis Rise region of the formation of Tharsis," he said.