Dubbed the Shalbatana lake after the much larger valley in which it is located, scientists believe it is as large as Lake Champlain, the mass of water that borders the United States and Canada, and could hold critical evidence of past life.Lead researcher Gaetano Di Achille of the University of Colorado at Boulder said: ‘This is the first unambiguous evidence of shorelines on the surface of Mars.The identification of the shorelines and accompanying geological evidence allows us to calculate the size and volume of the lake, which appears to have formed about 3.4billion years ago.The team constructed the ancient concept from images taken by a high-powered camera known as the High Resolution Imaging Science Experiment, or HiRISE, riding on the back of Nasa’s Mars Reconnaissance Orbiter.The HiRISE can resolve features on the surface down to just a metre (3.3 feet) in size from its orbit 200 miles (322 kilometres), about the distance from Brighton to York, above Mars.An analysis of the HiRISE images indicates that water carved a 30-mile-long canyon that opened up into a valley, depositing sediment into a large delta, the researchers say.