Plate tectonics, a phenomenon long thought to exist nowhere in our solar system but on Earth, is also taking place on Mars, a U.S. researcher says. The geological phenomenon, which involves the movement of huge crustal plates beneath a planet\'s surface, also exists on Mars, UCLA planetary geologist An Yin said. \"Mars is at a primitive stage of plate tectonics,\" he said. \"It gives us a glimpse of how the early Earth may have looked and may help us understand how plate tectonics began on Earth.\" Analyzing almost a hundred satellite images of Mars from two NASA spacecraft, Yin, who has conducted geologic research in the Himalayas and Tibet, said he found about a dozen that revealed evidence of plate tectonics. \"When I studied the satellite images from Mars, many of the features looked very much like fault systems I have seen in the Himalayas and Tibet, and in California as well, including the geomorphology,\" Yin said in a UCLA release Thursday. For example, he said, he noted a very smooth, flat side of a canyon wall, which can be generated only by a fault, and a steep cliff, comparable to cliffs in California\'s Death Valley, which also are generated by a fault. \"You don\'t see these features anywhere else on other planets in our solar system, other than Earth and Mars,\" Yin said. Plate tectonics on Earth, with seven major plates, are very much more active, he said. \"Earth has a very broken \'egg shell,\' so its surface has many plates; Mars\' is slightly broken and may be on the way to becoming very broken, except its pace is very slow due to its small size and, thus, less thermal energy to drive it,\" Yin said. \"This may be the reason Mars has fewer plates than [we see] on Earth.\" Yin said he is doubtful Mars has more than two plates. \"We have been able to identify only the two plates,\" he said. \"For the other areas on Mars, I think the chances are very, very small.\"